The document discusses the philosophy of seismic design of building structures. It explains that seismic design aims to allow some damage to occur in major earthquakes to avoid collapse, by designing structures to yield in specific zones. This dissipates energy through hysteretic damping. Structures are designed to remain elastic in minor quakes and have minimal damage in moderate quakes. Common lateral force resisting systems for reinforced concrete buildings are then described, including moment frames, shear walls, dual frames+walls, braced frames, trussed frames, and tube frames.
Performance Analysis of the Tall Structure with Diagrid for Seismic LoadingIRJET Journal
This document analyzes the performance of tall structures with diagrid frameworks under seismic loading. Three 18-story building models are created with square, octagonal, and circular plans using diagrid and shear wall systems. Linear static and dynamic analyses are performed using ETABS software. Results show the diagrid models have shorter natural periods and lower base shear, story displacement, and drift values compared to the equivalent shear wall models, indicating diagrid structures perform better seismically. The study aims to understand how diagrid systems help resist lateral loads in tall buildings.
This document provides an introduction and overview of the structural design considerations for tall buildings. It discusses how mankind has sought to build taller structures throughout history as symbols of power. For tall buildings, lateral loads from wind and earthquakes must be effectively resisted to prevent shear failure, overturning, or excessive deflection. Various lateral load resisting systems are explored, including moment frames, braced frames, tube structures, and outrigger systems. Rigidity indices are used to compare the bending and shear resistance of different structural configurations. The challenges of seismic design are also addressed. The document reviews previous research on improving the performance of reinforced concrete frames through the addition of bracing or shear walls.
Effect of steel bracing on vertically irregular r.c.c building frames under s...eSAT Journals
Abstract
Earthquakes are one of the most life threatening, environmental hazardous and destructive natural phenomenons that causes
shaking of ground. This result in damage to the structures, hence we need to design the buildings to withstand these earthquakes
which may occur at least once in the life time of the structure. Structures possess less stiffness and strength in case of irregular
configured frames; to enhance this, lateral load resisting systems are introduced into the frames. In this study, G+5 storey
building model has been analyzed considering different types of vertical geometric irregularities and steel bracings using
pushover analysis with the help of ETABS 9.7 software. Addition of X type brace, V type Brace and Inverted V/K type brace shows
that use of X-type of bracing is found more suitable to enhance the performance of the irregular buildings.
Key Words: pushover analysis, vertical irregularity, steel bracings, performance point.
Seismic Analysis of regular & Irregular RCC frame structuresDaanish Zama
This document discusses seismic analysis of regular and irregular reinforced concrete framed buildings. It analyzes 4 building models - a regular 4-story building, a stiffness irregular building with a soft ground story, and two vertically irregular buildings with setbacks on the 3rd floor and 2nd/3rd floors. Static analysis was performed to compare bending moments, shear forces, story drifts, and joint displacements. Results showed irregular buildings experienced higher seismic demands. The regular building performed best, with the single setback building also performing well. Irregular configurations increase seismic effects and should be minimized in design.
Seismic performance of r c buildings on sloping grounds with different types ...eSAT Journals
Abstract
Structure are highly susceptible to serve damages in earthquake scenario, so choosing an appropriate lateral force resisting
bracing systems will have a significant effect on performance of the structure. So this present study is aimed at evaluating and
comparing various types of eccentric steel bracings for 12 storey RC frame building resisting on sloping ground configurations.
For this 5 types of bracing systems like X-Bracing, Diagonal bracing, K- bracing, V-bracing and inverted V bracing are
considered on the outer periphery of the buildings with step back and set back – step back type configurations are modeled and
analyzed. The models are compared for different aspects within the structure, such as the maximum storey displacement, base
shear, storey drift and storey shear, the structure is analyzed for seismic zone V and medium soil condition as per IS 1893:2002
using ETABS software. Results conclude that on sloping ground due to irregularity on ground surface, the structures are more
vulnerable to earthquakes. Hence use of eccentric steel bracing is an effective and economical way to resist earthquake forces,
Inverted V type bracing performs well compared to other bracing types. By using inverted V type bracing in step back buildings
types maximum storey displacement of 70% and storey drift of 66% are obtained. Similarly for setback – step back configuration
maximum storey displacement of 74% and storey drift of 70% are obtained respectively.
Keywords: X-Bracing, Diagonal Bracing, K- Bracing, V-Bracing and Inverted V Bracing
Performance of shear wall building during seismic excitationsIAEME Publication
This document summarizes a study on the performance of shear wall buildings during seismic excitations. The study analyzed a 25-story building located in seismic zone 3, comparing the performance of two models: one with an L-shaped shear wall and one with a core-type shear wall. Time history analyses found that the building with the L-shaped wall experienced greater maximum displacement than the building with the core wall. Thus, providing shear walls as a core type can reduce story drift. Additionally, as the height of the building increases, shear walls absorb more lateral force than frames. Previous studies have also shown that shear walls with flanges perform better than walls without due to interaction between the flange and web.
This document discusses reinforced concrete shear walls. It provides definitions, design considerations, placement guidelines, and seismic behavior analysis. Shear walls are designed to resist lateral forces from earthquakes by providing strength, stiffness, and minimizing structural sway. Case studies demonstrate that high axial load ratios decrease ductility, and shear walls with staggered openings perform better seismically than those with regular openings.
Review paper on seismic responses of multistored rcc building with mass irreg...eSAT Journals
Abstract
From past earthquakes it is proved that many of structure are totally or partially damaged due to earthquake. So, it is necessary to determine seismic responses of such buildings. There are different techniques of seismic analysis of structure. Time history analysis is one of the important techniques for structural seismic analysis generally the evaluated structural response is non-linear in nature. For such type of analysis, a representative earthquake time history is required. In this project work seismic analysis of RCC buildings with mass irregularity at different floor level are carried out. Here for analysis different time histories have been used. This paper highlights the effect of mass irregularity on different floor in RCC buildings with time history and analysis is done by using ETABS software.
Keywords: Seismic Analysis, Time History Analysis, Base Shear, Storey Shear, Story Displacement.
Performance Analysis of the Tall Structure with Diagrid for Seismic LoadingIRJET Journal
This document analyzes the performance of tall structures with diagrid frameworks under seismic loading. Three 18-story building models are created with square, octagonal, and circular plans using diagrid and shear wall systems. Linear static and dynamic analyses are performed using ETABS software. Results show the diagrid models have shorter natural periods and lower base shear, story displacement, and drift values compared to the equivalent shear wall models, indicating diagrid structures perform better seismically. The study aims to understand how diagrid systems help resist lateral loads in tall buildings.
This document provides an introduction and overview of the structural design considerations for tall buildings. It discusses how mankind has sought to build taller structures throughout history as symbols of power. For tall buildings, lateral loads from wind and earthquakes must be effectively resisted to prevent shear failure, overturning, or excessive deflection. Various lateral load resisting systems are explored, including moment frames, braced frames, tube structures, and outrigger systems. Rigidity indices are used to compare the bending and shear resistance of different structural configurations. The challenges of seismic design are also addressed. The document reviews previous research on improving the performance of reinforced concrete frames through the addition of bracing or shear walls.
Effect of steel bracing on vertically irregular r.c.c building frames under s...eSAT Journals
Abstract
Earthquakes are one of the most life threatening, environmental hazardous and destructive natural phenomenons that causes
shaking of ground. This result in damage to the structures, hence we need to design the buildings to withstand these earthquakes
which may occur at least once in the life time of the structure. Structures possess less stiffness and strength in case of irregular
configured frames; to enhance this, lateral load resisting systems are introduced into the frames. In this study, G+5 storey
building model has been analyzed considering different types of vertical geometric irregularities and steel bracings using
pushover analysis with the help of ETABS 9.7 software. Addition of X type brace, V type Brace and Inverted V/K type brace shows
that use of X-type of bracing is found more suitable to enhance the performance of the irregular buildings.
Key Words: pushover analysis, vertical irregularity, steel bracings, performance point.
Seismic Analysis of regular & Irregular RCC frame structuresDaanish Zama
This document discusses seismic analysis of regular and irregular reinforced concrete framed buildings. It analyzes 4 building models - a regular 4-story building, a stiffness irregular building with a soft ground story, and two vertically irregular buildings with setbacks on the 3rd floor and 2nd/3rd floors. Static analysis was performed to compare bending moments, shear forces, story drifts, and joint displacements. Results showed irregular buildings experienced higher seismic demands. The regular building performed best, with the single setback building also performing well. Irregular configurations increase seismic effects and should be minimized in design.
Seismic performance of r c buildings on sloping grounds with different types ...eSAT Journals
Abstract
Structure are highly susceptible to serve damages in earthquake scenario, so choosing an appropriate lateral force resisting
bracing systems will have a significant effect on performance of the structure. So this present study is aimed at evaluating and
comparing various types of eccentric steel bracings for 12 storey RC frame building resisting on sloping ground configurations.
For this 5 types of bracing systems like X-Bracing, Diagonal bracing, K- bracing, V-bracing and inverted V bracing are
considered on the outer periphery of the buildings with step back and set back – step back type configurations are modeled and
analyzed. The models are compared for different aspects within the structure, such as the maximum storey displacement, base
shear, storey drift and storey shear, the structure is analyzed for seismic zone V and medium soil condition as per IS 1893:2002
using ETABS software. Results conclude that on sloping ground due to irregularity on ground surface, the structures are more
vulnerable to earthquakes. Hence use of eccentric steel bracing is an effective and economical way to resist earthquake forces,
Inverted V type bracing performs well compared to other bracing types. By using inverted V type bracing in step back buildings
types maximum storey displacement of 70% and storey drift of 66% are obtained. Similarly for setback – step back configuration
maximum storey displacement of 74% and storey drift of 70% are obtained respectively.
Keywords: X-Bracing, Diagonal Bracing, K- Bracing, V-Bracing and Inverted V Bracing
Performance of shear wall building during seismic excitationsIAEME Publication
This document summarizes a study on the performance of shear wall buildings during seismic excitations. The study analyzed a 25-story building located in seismic zone 3, comparing the performance of two models: one with an L-shaped shear wall and one with a core-type shear wall. Time history analyses found that the building with the L-shaped wall experienced greater maximum displacement than the building with the core wall. Thus, providing shear walls as a core type can reduce story drift. Additionally, as the height of the building increases, shear walls absorb more lateral force than frames. Previous studies have also shown that shear walls with flanges perform better than walls without due to interaction between the flange and web.
This document discusses reinforced concrete shear walls. It provides definitions, design considerations, placement guidelines, and seismic behavior analysis. Shear walls are designed to resist lateral forces from earthquakes by providing strength, stiffness, and minimizing structural sway. Case studies demonstrate that high axial load ratios decrease ductility, and shear walls with staggered openings perform better seismically than those with regular openings.
Review paper on seismic responses of multistored rcc building with mass irreg...eSAT Journals
Abstract
From past earthquakes it is proved that many of structure are totally or partially damaged due to earthquake. So, it is necessary to determine seismic responses of such buildings. There are different techniques of seismic analysis of structure. Time history analysis is one of the important techniques for structural seismic analysis generally the evaluated structural response is non-linear in nature. For such type of analysis, a representative earthquake time history is required. In this project work seismic analysis of RCC buildings with mass irregularity at different floor level are carried out. Here for analysis different time histories have been used. This paper highlights the effect of mass irregularity on different floor in RCC buildings with time history and analysis is done by using ETABS software.
Keywords: Seismic Analysis, Time History Analysis, Base Shear, Storey Shear, Story Displacement.
This document summarizes a thesis analyzing the seismic performance of a 13-story building model with and without shear walls. Two models are considered: a bare frame structure and a shear wall frame structure. Both models are analyzed using ETABS software under wind and earthquake loading conditions in Seismic Zone III. The results show that the shear wall structure performs much better in terms of limiting lateral displacement, storey drift, and increasing stiffness and strength. It is concluded that the shear wall frame structure provides more reliable performance against lateral loads.
MODAL AND RESPONSE SPECTRUM (IS 18932002) ANALYSIS 0F R.C FRAME BUILDING (IT ...Mintu Choudhury
This document discusses modeling a reinforced concrete frame building for seismic analysis. It describes modeling the building using frame elements in SAP 2000. Key elements include:
- Modeling beams and columns as frame elements
- Considering the building's diaphragm, which can be rigid, semi-rigid, or flexible
- Performing modal analysis to determine the building's vibration modes and periods
- Conducting response spectrum analysis and comparing results to the equivalent lateral force method
EFFECT OF SHEAR WALL AREA ON SEISMIC BEHAVIOR OF MULTI STORIED BUILDINGS WITH...Ijripublishers Ijri
The advances in three-dimensional structural analysis and computing resources have allowed the efficient
and safe design of increasingly taller structures. These structures are the consequence of increasing urban
densification and economic viability. The trend towards progressively taller structures has demanded a shift
from the traditional strength based design approach of buildings to a focus on constraining the overall motion
of the structure. Structural engineers have responded to this challenge of lateral control with a myriad
of systems that achieve motion control while adhering to the overall architectural vision.
Reinforced Concrete (RC) wall-frame buildings are widely recommended for urban construction in areas
with high seismic hazard. Presence of structural walls imparts a large stiffness to the lateral-force resisting
system of the building. Proper detailing of walls can also lead to ductile behavior of such structures during
strong earthquake shaking. One of the major parameters influencing the seismic behavior of wall-frame
buildings is the wall-area ratio. Thus shear wall area ratio is set as a key parameter which needs to be investigated
in this analytical study.
Seismic Analysis of Multistoreyed RC Building Due to Mass Irregularity by Tim...IRJET Journal
This document presents a study on the seismic analysis of a 12-story reinforced concrete building with and without mass irregularity using time history analysis. The building is modeled and analyzed using ETABS software considering the Bhuj earthquake record. Lead rubber bearings are designed and used as base isolators. Parameters like base shear, time period, and story displacement are compared for regular and irregular buildings with fixed base and base isolated conditions. The results show that base isolation is effective in reducing base shear by up to 49% and increasing time period, while mass irregularity increases base shear and time period compared to the regular fixed base building.
Aerodynamic optimization of building shapesAglaia Connect
Aerodynamic optimization of building shapes is an important portion of super-tall building design. Two categories of optimization are discussed in the paper: aerodynamic modifications that are normally considered as remedial measures; and aerodynamic designs that integrate architectural design with aerodynamic study in the early design stage.
aerodynamic shape optimization
aerodynamic shape design
best aerodynamic shapes
aerodynamic shape factor
ideal aerodynamic shape
best aerodynamic car shape
aerodynamic shapes and drag
what is the most aerodynamic shape
interesting civil engineering topics
seminar topics pdf
civil engineering topics for presentation
civil seminar topics ppt
best seminar topics for civil engineering
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ANALYSIS OF SOFT STOREY FOR MULTI STORYED BUILDING IN ZONE-4Ijripublishers Ijri
This document analyzes the soft story effect in multi-story buildings located in seismic zone 4 of India. A soft story is defined as a story with significantly less stiffness than adjacent stories, often due to large open spaces. The document describes a model of a 21-story building analyzed using ETABS software. Results show increased displacement and drift when soft stories are located at lower floors compared to upper floors. Design of structural elements in soft stories must account for increased lateral loads during earthquakes. Providing shear walls can increase story stiffness and improve seismic performance of buildings with soft stories.
IRJET- Comparative Analysis of Regular and Irregular Configuration of Mul...IRJET Journal
This document analyzes the response of regular and irregularly configured multistory buildings in medium soil and various seismic zones. A 30-story building is modeled in ETABS software with both regular and irregular configurations. The models are analyzed using response spectrum analysis in seismic zones II and V. Results show that the irregular building experiences higher story displacements, drifts, forces, and accelerations compared to the regular building. The regular building has higher story stiffness and lower base shear. Therefore, irregular configurations perform poorer under earthquake loading with increased damage potential.
Drift analysis and Comparison due to rigid frame structureFarok Ahmed
This document summarizes a student project analyzing drift in rigid frame structures due to lateral loads like earthquakes. It presents analytical calculations of drift using a developed C++ program and compares the results to drift values obtained from ETABS software analysis. The study found that drift increases with building height and number of spans, and decreases with increasing beam and column dimensions and shear values. Drift values from the programming analysis agreed well with those from the ETABS model. The results provide insight into how lateral loads affect drift in tall buildings.
Earthquake load as per nbc 105 and is 1893Binay Shrestha
This document provides an overview of earthquake resistant design philosophy and concepts in building codes. It discusses key topics such as:
- The goal of earthquake resistant rather than earthquake proof design, allowing some damage to occur and dissipate energy.
- Designing structures to resist minor, moderate, and major earthquakes without collapse through ductility and overstrength.
- Methods of seismic analysis including static coefficient and response spectrum approaches.
- Factors influencing earthquake forces such as seismic hazard, structural properties, and performance objectives.
- Detailing requirements for ductile moment frames and bracing systems.
Lateral Load Analysis of Shear Wall and Concrete Braced Multi-Storeyed R.C Fr...ijsrd.com
This document analyzes the lateral load performance of different reinforced concrete frame models of a 12-story building using structural analysis software. Eight models are considered: a bare frame, fully infilled frame, frames infilled except the ground floor, and frames with shear walls, core walls or bracing in different configurations. Dynamic analysis shows fundamental periods are lowest for models with shear walls or bracing. Base shear and story drifts are highest for the bare frame and reduced by over 60% for infilled models. Models with ground soft-first story have increased drift, but shear walls or bracing can reduce drift by over 80% compared to the bare frame. Story displacements also decrease significantly with infilling or lateral load resisting elements.
EFFECT OF POSITIONING OF RC SHEAR WALLS OF DIFFERENT SHAPES ON SEISMIC PERFOR...IAEME Publication
The buildings situated on hill slopes in earthquake prone areas are generally irregular, torsionally coupled. Hence, subjected to severe damage when affected by earthquake ground motion. Such buildings have mass & stiffness varying along the vertical & horizontal planes, resulting the center of mass & center of rigidity do not coincide on various floors, they demand torsional analysis, in addition to lateral forces under the action of earthquakes. This study compels with a studies on the seismic behavior of buildings resting on sloping ground with a shear walls. It is observed that the seismic behavior of buildings on sloping ground differ from other buildings.
IRJET- Post Peak Response of Reinforced Concrete Frames with and without in F...IRJET Journal
This document discusses the effect of masonry infill panels, cross bracing, and viscous dampers on the seismic response of reinforced concrete frames. It analyzes a 7-story reinforced concrete building model with and without these elements using nonlinear static analysis. The addition of masonry infill walls, cross bracing, and viscous dampers reduces storey displacements and drift compared to the bare frame model. The equivalent strut method is used to model the infill walls, and cross bracing is modeled using diagonal steel braces. Viscous dampers absorb seismic energy to damp the motion of the building. Nonlinear static pushover analysis is performed using ETABS and SAP2000 software.
1 seismic behaviors of columns in ordinary and intermediate moment resisting ...sharif tanvir
The document summarizes a study that investigated the seismic behavior of columns in ordinary moment resisting concrete frames (OMRCF) and intermediate moment resisting concrete frames (IMRCF). Eight column specimens were tested under various loading conditions to evaluate factors like axial load type, existence of lap splices, and frame type. The test results showed that the column specimens had strengths and drift capacities greater than code requirements, though capacities varied depending on lap splices and transverse reinforcement spacing.
Seismic Capacity Comparisons of Reinforced Concrete Buildings Between Standar...drboon
Earthquakes are cause of serious damage through the building. Therefore, moment resistant frame buildings are widely used as lateral resisting system. Generally three types of moment resisting frames are designed namely Special ductile frames (SDF), Intermediate ductile frames (IDF) and Gravity load designed (GLD) frames, each of which has a certain level of ductility. Comparative studies on the seismic performance of three different ductility of building are performed in this study. The analytical models are considered about failure mode of column (i.e. shear failure, flexural to shear failure and flexural failure); beam-column joint connection, infill wall and flexural foundation. Concepts of incremental dynamic analysis are practiced to assess the required data for performance based evaluations. This study found that the lateral load capacity of GLD, IDF, and SDF building was 19.25, 27.87, and 25.92 %W respectively. The average response spectrum at the collapse state for GLD, IDF, and SDF are 0.75 g, 1.19 g, and 1.33 g, respectively. The results show that SDF is more ductile than IDF and the initial strength of SDF is close to IDF. The results indicate that all of frames are able to resistant a design earthquake.
Seismic Analysis of Regular and Irregular Buildings with Vertical Irregularit...IRJET Journal
This document analyzes the seismic response of regular and irregular buildings with vertical irregularities using STAAD.Pro software. Six building models are analyzed - three regular buildings with stepped, inverted-T, and U-shaped vertical irregularities, and three irregular (H-shaped plan) buildings with the same vertical irregularities. Response spectrum analysis is used to determine maximum displacements, base shear, frequencies, and time periods. Results show irregular buildings have higher displacements and lower frequencies than regular buildings. The regular building with a U-shaped vertical irregularity performed the worst with the highest displacements. In conclusion, regular buildings performed better seismically than irregular buildings with vertical irregularities.
EFFECT OF SHAPE OF TALL BUILDINGS SUBJECTED TO WIND LOADINGIAEME Publication
Objectives: To study the effect and variation of wind pressure with the shape, rounding of the corners and height of the structure. Methods: Aerodynamic approach is architecture is the extreme approach in the design of tall buildings. In the present thesis, multistory buildings of 40 storey, 60 storey and 80 storey were modelled for different shapes of structures i.e. Rectangular structure, Rectangular structure with rounded corners, Square structure, Square structure with rounded corners, Circular structure and Elliptical structure. Findings: The influence of height and shapes on gust loads and its effects on the response of the structure are studied in the present case. The analysis of the building has been carried out using standard commercial software (STAAD PRO) and the estimation of wind loads is done by Indian standard code IS-875(Part-3). The effect of rounding of the corners of tall structures is studied through computational fluid dynamics (CFD) on pressure distribution on the surface of the structure. Novelty: Standard software fluent is used for CFD analysis.
PERFORMANCE BASED ANALYSIS OF VERTICALLY IRREGULAR STRUCTURE UNDER VARIOUS SE...Ijripublishers Ijri
In the recent years a lot of attention has been given to the earthquake analysis of structure it is one of the most devastating
natural calamity and which causes severe damage not only to the properties but also to the lives. This is the
reason there has been a lot of focus on the structures to be earthquake resistant. Buildings get damaged mostly due
to the earthquake ground motions. In an earthquake, the building base experiences high frequency movements, which
results in the inertial force on the building and its components and this problem gets worse when a structure is irregular
in shape, size etc,. Therefore, there is a lot to work on the seismic behavior of the irregular building which might not
respond the way regular building does. It makes the irregular building quite more complex and unpredictable during
the course of an earthquake.
Structural design including disaster (wind & cyclone land slide_eq_ resistan...RAJESH JAIN
The document summarizes key aspects of structural design as outlined in Part 6 of the National Building Code of India, with a focus on loads, forces, and earthquake resistance. It discusses the sections and standards covered in Part 6, including loads from wind, seismic activity, imposed loads, and more. Methods of calculating design wind speed and pressure are presented. Seismic zoning maps and factors are shown, along with equations for determining design lateral force based on seismic weight and acceleration spectra. Types of structural irregularities are defined.
STUDY ON SEISMIC EFFECT OF HIGH RISE BUILDING SHEAR WALL/WALL WITHOUT SHEAR WALLIAEME Publication
This document analyzes the seismic effects on high-rise buildings with and without shear walls in zones II and III. Analytical models of G+5, G+10, and G+15 buildings were created in STAAD Pro and analyzed using the equivalent static method. Results show that lateral displacement is less in buildings with special moment resisting frames (SMRF) using shear walls compared to ordinary moment resisting frames (OMRF) without shear walls. The maximum difference in storey drift between SMRF and OMRF increases from 0.15% for G+5 to 0.66% for G+15 buildings in zone III, and from 0.04% to 0.41% respectively in zone II.
Earthquake resistant analysis and design of multistoried buildingAnup Adhikari
The document describes the seismic analysis and design of a multistoried reinforced concrete building. It discusses the objectives, background, literature review, methodology, and concepts for reducing earthquake effects. The methodology section explains the functional and structural planning, load assessment including gravity and lateral loads, preliminary design of structural elements like slabs, beams and columns. It also discusses drift calculation and load path. The design and detailing section provides details on the design of structural components like slab, beam, column, staircase, footing and basement wall based on Indian codes.
تقرير فني -تدعيم المبنى مع الرسوم ضد الزلازل.docxAdnan Lazem
This document provides an introduction to seismic design of buildings. It discusses key structural actions like bending moments, shear forces, and ductile behavior that allow structures to deform without losing strength. Response spectra are used to determine design seismic actions based on a structure's dynamic properties and site conditions. Ductile design allows structures to withstand major earthquakes through controlled cracking and yielding. Higher modes of vibration and P-delta effects are also considered in design.
This document discusses the analysis of a reinforced concrete (RC) multi-story commercial building in different seismic zones (II, III, IV, and V) in India using the ETABS software. The objectives are to study the behavior of the building when subjected to earthquake loads and to compare the analysis results across different seismic zones. A 20-story building model with constant floor height of 3m is analyzed. The effects of varying the seismic zone factor on the building's seismic performance are interpreted from the results.
This document summarizes a thesis analyzing the seismic performance of a 13-story building model with and without shear walls. Two models are considered: a bare frame structure and a shear wall frame structure. Both models are analyzed using ETABS software under wind and earthquake loading conditions in Seismic Zone III. The results show that the shear wall structure performs much better in terms of limiting lateral displacement, storey drift, and increasing stiffness and strength. It is concluded that the shear wall frame structure provides more reliable performance against lateral loads.
MODAL AND RESPONSE SPECTRUM (IS 18932002) ANALYSIS 0F R.C FRAME BUILDING (IT ...Mintu Choudhury
This document discusses modeling a reinforced concrete frame building for seismic analysis. It describes modeling the building using frame elements in SAP 2000. Key elements include:
- Modeling beams and columns as frame elements
- Considering the building's diaphragm, which can be rigid, semi-rigid, or flexible
- Performing modal analysis to determine the building's vibration modes and periods
- Conducting response spectrum analysis and comparing results to the equivalent lateral force method
EFFECT OF SHEAR WALL AREA ON SEISMIC BEHAVIOR OF MULTI STORIED BUILDINGS WITH...Ijripublishers Ijri
The advances in three-dimensional structural analysis and computing resources have allowed the efficient
and safe design of increasingly taller structures. These structures are the consequence of increasing urban
densification and economic viability. The trend towards progressively taller structures has demanded a shift
from the traditional strength based design approach of buildings to a focus on constraining the overall motion
of the structure. Structural engineers have responded to this challenge of lateral control with a myriad
of systems that achieve motion control while adhering to the overall architectural vision.
Reinforced Concrete (RC) wall-frame buildings are widely recommended for urban construction in areas
with high seismic hazard. Presence of structural walls imparts a large stiffness to the lateral-force resisting
system of the building. Proper detailing of walls can also lead to ductile behavior of such structures during
strong earthquake shaking. One of the major parameters influencing the seismic behavior of wall-frame
buildings is the wall-area ratio. Thus shear wall area ratio is set as a key parameter which needs to be investigated
in this analytical study.
Seismic Analysis of Multistoreyed RC Building Due to Mass Irregularity by Tim...IRJET Journal
This document presents a study on the seismic analysis of a 12-story reinforced concrete building with and without mass irregularity using time history analysis. The building is modeled and analyzed using ETABS software considering the Bhuj earthquake record. Lead rubber bearings are designed and used as base isolators. Parameters like base shear, time period, and story displacement are compared for regular and irregular buildings with fixed base and base isolated conditions. The results show that base isolation is effective in reducing base shear by up to 49% and increasing time period, while mass irregularity increases base shear and time period compared to the regular fixed base building.
Aerodynamic optimization of building shapesAglaia Connect
Aerodynamic optimization of building shapes is an important portion of super-tall building design. Two categories of optimization are discussed in the paper: aerodynamic modifications that are normally considered as remedial measures; and aerodynamic designs that integrate architectural design with aerodynamic study in the early design stage.
aerodynamic shape optimization
aerodynamic shape design
best aerodynamic shapes
aerodynamic shape factor
ideal aerodynamic shape
best aerodynamic car shape
aerodynamic shapes and drag
what is the most aerodynamic shape
interesting civil engineering topics
seminar topics pdf
civil engineering topics for presentation
civil seminar topics ppt
best seminar topics for civil engineering
seminar topics for mechanical engineers
civil engineering ppt
latest civil engineering seminar topics
ANALYSIS OF SOFT STOREY FOR MULTI STORYED BUILDING IN ZONE-4Ijripublishers Ijri
This document analyzes the soft story effect in multi-story buildings located in seismic zone 4 of India. A soft story is defined as a story with significantly less stiffness than adjacent stories, often due to large open spaces. The document describes a model of a 21-story building analyzed using ETABS software. Results show increased displacement and drift when soft stories are located at lower floors compared to upper floors. Design of structural elements in soft stories must account for increased lateral loads during earthquakes. Providing shear walls can increase story stiffness and improve seismic performance of buildings with soft stories.
IRJET- Comparative Analysis of Regular and Irregular Configuration of Mul...IRJET Journal
This document analyzes the response of regular and irregularly configured multistory buildings in medium soil and various seismic zones. A 30-story building is modeled in ETABS software with both regular and irregular configurations. The models are analyzed using response spectrum analysis in seismic zones II and V. Results show that the irregular building experiences higher story displacements, drifts, forces, and accelerations compared to the regular building. The regular building has higher story stiffness and lower base shear. Therefore, irregular configurations perform poorer under earthquake loading with increased damage potential.
Drift analysis and Comparison due to rigid frame structureFarok Ahmed
This document summarizes a student project analyzing drift in rigid frame structures due to lateral loads like earthquakes. It presents analytical calculations of drift using a developed C++ program and compares the results to drift values obtained from ETABS software analysis. The study found that drift increases with building height and number of spans, and decreases with increasing beam and column dimensions and shear values. Drift values from the programming analysis agreed well with those from the ETABS model. The results provide insight into how lateral loads affect drift in tall buildings.
Earthquake load as per nbc 105 and is 1893Binay Shrestha
This document provides an overview of earthquake resistant design philosophy and concepts in building codes. It discusses key topics such as:
- The goal of earthquake resistant rather than earthquake proof design, allowing some damage to occur and dissipate energy.
- Designing structures to resist minor, moderate, and major earthquakes without collapse through ductility and overstrength.
- Methods of seismic analysis including static coefficient and response spectrum approaches.
- Factors influencing earthquake forces such as seismic hazard, structural properties, and performance objectives.
- Detailing requirements for ductile moment frames and bracing systems.
Lateral Load Analysis of Shear Wall and Concrete Braced Multi-Storeyed R.C Fr...ijsrd.com
This document analyzes the lateral load performance of different reinforced concrete frame models of a 12-story building using structural analysis software. Eight models are considered: a bare frame, fully infilled frame, frames infilled except the ground floor, and frames with shear walls, core walls or bracing in different configurations. Dynamic analysis shows fundamental periods are lowest for models with shear walls or bracing. Base shear and story drifts are highest for the bare frame and reduced by over 60% for infilled models. Models with ground soft-first story have increased drift, but shear walls or bracing can reduce drift by over 80% compared to the bare frame. Story displacements also decrease significantly with infilling or lateral load resisting elements.
EFFECT OF POSITIONING OF RC SHEAR WALLS OF DIFFERENT SHAPES ON SEISMIC PERFOR...IAEME Publication
The buildings situated on hill slopes in earthquake prone areas are generally irregular, torsionally coupled. Hence, subjected to severe damage when affected by earthquake ground motion. Such buildings have mass & stiffness varying along the vertical & horizontal planes, resulting the center of mass & center of rigidity do not coincide on various floors, they demand torsional analysis, in addition to lateral forces under the action of earthquakes. This study compels with a studies on the seismic behavior of buildings resting on sloping ground with a shear walls. It is observed that the seismic behavior of buildings on sloping ground differ from other buildings.
IRJET- Post Peak Response of Reinforced Concrete Frames with and without in F...IRJET Journal
This document discusses the effect of masonry infill panels, cross bracing, and viscous dampers on the seismic response of reinforced concrete frames. It analyzes a 7-story reinforced concrete building model with and without these elements using nonlinear static analysis. The addition of masonry infill walls, cross bracing, and viscous dampers reduces storey displacements and drift compared to the bare frame model. The equivalent strut method is used to model the infill walls, and cross bracing is modeled using diagonal steel braces. Viscous dampers absorb seismic energy to damp the motion of the building. Nonlinear static pushover analysis is performed using ETABS and SAP2000 software.
1 seismic behaviors of columns in ordinary and intermediate moment resisting ...sharif tanvir
The document summarizes a study that investigated the seismic behavior of columns in ordinary moment resisting concrete frames (OMRCF) and intermediate moment resisting concrete frames (IMRCF). Eight column specimens were tested under various loading conditions to evaluate factors like axial load type, existence of lap splices, and frame type. The test results showed that the column specimens had strengths and drift capacities greater than code requirements, though capacities varied depending on lap splices and transverse reinforcement spacing.
Seismic Capacity Comparisons of Reinforced Concrete Buildings Between Standar...drboon
Earthquakes are cause of serious damage through the building. Therefore, moment resistant frame buildings are widely used as lateral resisting system. Generally three types of moment resisting frames are designed namely Special ductile frames (SDF), Intermediate ductile frames (IDF) and Gravity load designed (GLD) frames, each of which has a certain level of ductility. Comparative studies on the seismic performance of three different ductility of building are performed in this study. The analytical models are considered about failure mode of column (i.e. shear failure, flexural to shear failure and flexural failure); beam-column joint connection, infill wall and flexural foundation. Concepts of incremental dynamic analysis are practiced to assess the required data for performance based evaluations. This study found that the lateral load capacity of GLD, IDF, and SDF building was 19.25, 27.87, and 25.92 %W respectively. The average response spectrum at the collapse state for GLD, IDF, and SDF are 0.75 g, 1.19 g, and 1.33 g, respectively. The results show that SDF is more ductile than IDF and the initial strength of SDF is close to IDF. The results indicate that all of frames are able to resistant a design earthquake.
Seismic Analysis of Regular and Irregular Buildings with Vertical Irregularit...IRJET Journal
This document analyzes the seismic response of regular and irregular buildings with vertical irregularities using STAAD.Pro software. Six building models are analyzed - three regular buildings with stepped, inverted-T, and U-shaped vertical irregularities, and three irregular (H-shaped plan) buildings with the same vertical irregularities. Response spectrum analysis is used to determine maximum displacements, base shear, frequencies, and time periods. Results show irregular buildings have higher displacements and lower frequencies than regular buildings. The regular building with a U-shaped vertical irregularity performed the worst with the highest displacements. In conclusion, regular buildings performed better seismically than irregular buildings with vertical irregularities.
EFFECT OF SHAPE OF TALL BUILDINGS SUBJECTED TO WIND LOADINGIAEME Publication
Objectives: To study the effect and variation of wind pressure with the shape, rounding of the corners and height of the structure. Methods: Aerodynamic approach is architecture is the extreme approach in the design of tall buildings. In the present thesis, multistory buildings of 40 storey, 60 storey and 80 storey were modelled for different shapes of structures i.e. Rectangular structure, Rectangular structure with rounded corners, Square structure, Square structure with rounded corners, Circular structure and Elliptical structure. Findings: The influence of height and shapes on gust loads and its effects on the response of the structure are studied in the present case. The analysis of the building has been carried out using standard commercial software (STAAD PRO) and the estimation of wind loads is done by Indian standard code IS-875(Part-3). The effect of rounding of the corners of tall structures is studied through computational fluid dynamics (CFD) on pressure distribution on the surface of the structure. Novelty: Standard software fluent is used for CFD analysis.
PERFORMANCE BASED ANALYSIS OF VERTICALLY IRREGULAR STRUCTURE UNDER VARIOUS SE...Ijripublishers Ijri
In the recent years a lot of attention has been given to the earthquake analysis of structure it is one of the most devastating
natural calamity and which causes severe damage not only to the properties but also to the lives. This is the
reason there has been a lot of focus on the structures to be earthquake resistant. Buildings get damaged mostly due
to the earthquake ground motions. In an earthquake, the building base experiences high frequency movements, which
results in the inertial force on the building and its components and this problem gets worse when a structure is irregular
in shape, size etc,. Therefore, there is a lot to work on the seismic behavior of the irregular building which might not
respond the way regular building does. It makes the irregular building quite more complex and unpredictable during
the course of an earthquake.
Structural design including disaster (wind & cyclone land slide_eq_ resistan...RAJESH JAIN
The document summarizes key aspects of structural design as outlined in Part 6 of the National Building Code of India, with a focus on loads, forces, and earthquake resistance. It discusses the sections and standards covered in Part 6, including loads from wind, seismic activity, imposed loads, and more. Methods of calculating design wind speed and pressure are presented. Seismic zoning maps and factors are shown, along with equations for determining design lateral force based on seismic weight and acceleration spectra. Types of structural irregularities are defined.
STUDY ON SEISMIC EFFECT OF HIGH RISE BUILDING SHEAR WALL/WALL WITHOUT SHEAR WALLIAEME Publication
This document analyzes the seismic effects on high-rise buildings with and without shear walls in zones II and III. Analytical models of G+5, G+10, and G+15 buildings were created in STAAD Pro and analyzed using the equivalent static method. Results show that lateral displacement is less in buildings with special moment resisting frames (SMRF) using shear walls compared to ordinary moment resisting frames (OMRF) without shear walls. The maximum difference in storey drift between SMRF and OMRF increases from 0.15% for G+5 to 0.66% for G+15 buildings in zone III, and from 0.04% to 0.41% respectively in zone II.
Earthquake resistant analysis and design of multistoried buildingAnup Adhikari
The document describes the seismic analysis and design of a multistoried reinforced concrete building. It discusses the objectives, background, literature review, methodology, and concepts for reducing earthquake effects. The methodology section explains the functional and structural planning, load assessment including gravity and lateral loads, preliminary design of structural elements like slabs, beams and columns. It also discusses drift calculation and load path. The design and detailing section provides details on the design of structural components like slab, beam, column, staircase, footing and basement wall based on Indian codes.
تقرير فني -تدعيم المبنى مع الرسوم ضد الزلازل.docxAdnan Lazem
This document provides an introduction to seismic design of buildings. It discusses key structural actions like bending moments, shear forces, and ductile behavior that allow structures to deform without losing strength. Response spectra are used to determine design seismic actions based on a structure's dynamic properties and site conditions. Ductile design allows structures to withstand major earthquakes through controlled cracking and yielding. Higher modes of vibration and P-delta effects are also considered in design.
This document discusses the analysis of a reinforced concrete (RC) multi-story commercial building in different seismic zones (II, III, IV, and V) in India using the ETABS software. The objectives are to study the behavior of the building when subjected to earthquake loads and to compare the analysis results across different seismic zones. A 20-story building model with constant floor height of 3m is analyzed. The effects of varying the seismic zone factor on the building's seismic performance are interpreted from the results.
ANALYSIS AND DESIGN OPTIMIZATION OF SHEAR-WALL IN CASE OF HIGH-RISE BUILDING ...IRJET Journal
The document analyzes and optimizes the design of shear walls in a high-rise building using ETABS software. It discusses modeling a 10-story building in ETABS with and without shear walls, and making design adjustments to the shear wall configuration. Results for story displacement and drift are compared between the models. The optimized model with design adjustments to the shear wall configuration showed reductions in story displacement and drift compared to the initial model without shear walls.
SHEAR WALL ANALYSIS & DESIGN OPTIMIZATION IN HIGH RISE BUILDINGSIRJET Journal
The document discusses the analysis and optimization of shear walls in high-rise buildings. It begins with an abstract that outlines analyzing a 19-story residential building with and without shear walls to compare vertical loads, moments, lateral forces, and torsion moments at each floor. It then discusses using optimization techniques to address structural engineering issues for high-rise buildings, including size and topological optimization while considering stability, safety, and load responses. The remainder of the document provides details on planning, design, and analysis of shear walls, including comparing walls to conventional construction and discussing forces on shear walls. It also covers the scope, literature review, analysis methods using software, and definitions of structural optimization.
IRJET-Effective Location Of Shear Walls and Bracings for Multistoried BuildingIRJET Journal
This document analyzes the effectiveness of different structural configurations for resisting lateral loads in a 10-story building subject to seismic activity. Two structural models are considered: a normal building frame and a dual system with shear walls and bracings placed at the building corners. Both models are analyzed using time history analysis in STAAD-Pro. Results show that the dual system experiences significantly less lateral deflection, with displacements reduced by 86-89% compared to the normal frame building. Additionally, the dual system sees only minor reductions in maximum shear force and bending moment compared to the normal frame building. Therefore, the dual system with corner shear walls and bracings provides greatly enhanced seismic performance over a normal framed building.
Effective Location Of Shear Walls and Bracings for Multistoried BuildingIRJET Journal
This document describes a study analyzing the effective placement of shear walls and bracings in a 10-story building to resist seismic forces. Two structural models are developed - a normal building frame and a dual system with shear walls and bracings at the building corners. Both models are analyzed using time history analysis in STAAD-Pro. The results show that the dual system with shear walls and bracings has significantly less lateral deflection under earthquake loading compared to the normal building frame, with deflections reduced by over 70% at the top story. This demonstrates that a combination of shear walls and bracings located at the building corners can greatly enhance the seismic performance of a multi-story building by reducing lateral displacements and
A Review of “Seismic Response of RC Structures Having Plan and Vertical Irreg...IRJET Journal
This document summarizes and reviews a research paper on the seismic response of reinforced concrete (RC) structures with plan and vertical irregularities, with and without infill walls. It discusses how infill walls can improve or reduce the seismic performance of RC buildings, depending on factors like wall layout, height distribution, connection to the frame, and relative stiffness of walls and frames. The reviewed research paper analyzes the behavior of infill walls, effects of vertical irregularities, and seismic performance of high-rise structures under linear static and dynamic analysis. It studies response characteristics like story drift, deflection and shear. The document also provides literature on similar research investigating the effects of infill walls, soft stories, plan irregularities, and different
A THEORETICAL STUDY ON COLLAPSE MECHANISM AND STRUCTURAL BEHAVIOR OF MULTI-ST...nhandoan10
This document presents a theoretical study on the collapse mechanism and structural behavior of multi-story reinforced concrete (RC) frames subjected to earthquake loading. A nonlinear finite element analysis was utilized to investigate the behavior and collapse mechanism. Plastic hinges were assumed to occur when steel yields or concrete reaches ultimate strength. The behavior of RC frames was investigated focusing on propagation of plastic hinges with varying numbers of stories, concrete grades, and reinforcement ratios, under three earthquake motions. Parameters like member rotations, hinge formation times, maximum shear and displacements were examined. Several conclusions were drawn regarding plastic hinge behavior and design of RC frames under seismic loads.
The document discusses various structural systems and construction techniques used in high-rise buildings. It describes the different types of structural systems including load bearing, framed, shell, and cable structures. It also discusses the various types of loads buildings must be designed for including dead, imposed, wind, snow, earthquake, and other loads. The document then covers seismic technologies used for earthquake resistance including passive, active, semi-active and hybrid control systems. It provides details on base isolation and passive energy dissipating devices. Finally, the document discusses developing construction techniques, environmental impact materials, and green/eco-friendly building concepts.
Special moment frames are reinforced concrete frames designed to resist earthquakes through flexural, axial, and shearing actions. They have additional proportioning and detailing requirements compared to intermediate or ordinary moment frames to improve seismic resistance. This includes the strong column weak beam design where the sum of the flexural strengths of the columns at a joint must exceed 120% of the sum of the flexural strengths of the beams to ensure plastic hinges form in the beams before the columns. Proper hinge reinforcement is also required to allow hinges to undergo large rotations without losing strength.
This document discusses the history and technical background of design drift requirements in building codes. It explains that code provisions for calculating seismic drift have changed substantially over the past 40 years, though the reasons for these changes are not well documented. The document focuses on minimum base shear requirements for determining drift in long-period structures, and discusses the reasoning behind current code equations. It also explores the effects of drift on structural elements, nonstructural components, and adjacent buildings.
IRJET- Seismic Effects on Irregular Buildings- State of the ArtIRJET Journal
This document summarizes research on the seismic effects on irregular buildings. It begins by defining irregular buildings as those with irregular distributions of mass, stiffness, or strength along the height. Previous earthquakes have shown damage is greater in irregular buildings. The document then discusses several recent studies that have evaluated the seismic response of irregular buildings through modeling and analysis, finding increased stresses, drift, and torsion effects compared to regular buildings. It concludes that accurately evaluating the seismic behavior of irregular buildings remains challenging.
Effect of Seismic Zone and Story Height on Response Reduction Factor for SMRF...P. Pravin Kumar Venkat Rao
This document discusses a study on the variation of response reduction factors for steel moment resisting frames (SMRFs) designed according to Indian seismic code IS 1893(Part-1):2002. 12 SMRFs of varying heights (3, 5, and 7 stories) located in different seismic zones (II-V) were analyzed. Non-linear static pushover analysis was used to determine the overstrength, ductility reduction, and overall response reduction factors for each frame. The results showed that these factors varied based on the number of stories and seismic zone, which is significant for seismic codes that do not currently account for such variations.
Earthquake engineering is the study of protecting society from earthquakes by limiting seismic risk. It involves analyzing how structures respond to seismic waves and designing structures to withstand earthquakes while sustaining minimal damage. The goals are to predict earthquake impacts and design/maintain structures to code standards. Research involves experimental testing using shake tables and computational modeling to understand structural behavior and improve designs. Seismic vibration control methods aim to mitigate earthquake impacts, including base isolation devices that decouple structures from shaking ground.
Study on Torsional Response of Irregualr Buildings Under Seismic LoadingIRJET Journal
This document discusses the torsional response of irregular buildings under seismic loading. It begins with an abstract that outlines the purpose of studying how irregular structures respond to torsional loads caused by earthquakes. Several methods of seismic analysis are then described. The concept of torsional irregularity is defined according to building codes. Previous studies on the torsional response of irregular structures are summarized, finding increased seismic demand and sensitivity for structures with irregular plans or vertical setbacks. The conclusion is that structural irregularities can significantly reduce seismic performance by increasing torsional forces, and proper design is needed to control torsion effects in irregular structures.
Evaluation of the Seismic Response Parameters for Infilled Reinforced Concret...IOSRJMCE
This document summarizes an analytical study that evaluated the seismic response parameters of reinforced concrete frame buildings with masonry infill walls. Finite element models were developed for 5, 7, and 10-story buildings with different infill configurations to investigate the effect of parameters like infill ratio and geometry. The infill walls were modeled using a diagonal strut approach. Nonlinear static analyses were performed to determine response values like maximum strength, displacement, ductility, and proposed modification factors according to codes. The study aimed to develop a matrix of realistic modification factors for medium-rise infilled frame buildings under lateral loads.
this presentation is about how you can make a building more resistant to earthquakes. Different techniques and designs are discussed to make a building more resistant to earthquakes. examples of different earthquake resistant buildings are also discussed.
This document summarizes the analysis and capacity based earthquake resistant design of a multi-storey reinforced concrete building. It begins with an introduction describing the need for earthquake resistant design of multi-storey buildings. It then describes the experimental program and methodology for capacity based design. This includes designing beams to act as ductile weak links and columns to remain elastic. The document then provides details of analyzing a G+6 building model in STAAD Pro, including load calculations and modeling the 3D reinforced concrete frame. It concludes with sections on capacity based design basics and analyzing the frame for gravity and seismic loads.
Analysis and Capacity Based Earthquake Resistance Design of Multy Bay Multy S...IJERA Editor
This document summarizes the analysis and capacity based earthquake resistant design of a multi-bay, multi-story residential building. A nonlinear static pushover analysis was performed on the building model in ETABS2015 to estimate the structure's ultimate capacity and failure mechanisms. The analysis found plastic hinge formation and indicated damage levels at different load steps. Capacity curves and capacity spectrum curves were generated from the pushover analysis in both horizontal directions. Story displacements from the pushover analysis and response spectrum analysis are also reported. The results provide estimates of the building's strength, deformation capacities, and expected performance under seismic loads.
IRJET- Comparative Analysis of Square Shape RC Frame by Replacing Masonry fro...IRJET Journal
This document presents a comparative analysis of square shaped reinforced concrete frames with and without masonry infill using response spectrum analysis. Masonry infill walls are commonly used to fill gaps in RC frames but are often ignored in design. The study models an 8-story RC building in ETABS and replaces the masonry infill with an equivalent diagonal strut. Response spectrum analysis is performed for different relative stiffness levels by reducing the strut width by 5-50%. Parameters like time period, base shear, storey displacement and stiffness are compared. Results show infill increases stiffness and strength but displacement increases as strut width decreases. Infill frames generally perform better seismically than bare frames by reducing displacements and increasing stiffness
TIME DIVISION MULTIPLEXING TECHNIQUE FOR COMMUNICATION SYSTEMHODECEDSIET
Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
2. THE PHILOSOPHY OF SEISMIC DESIGN
Lecture 2
THE PHILOSOPHY OF SEISMIC DESIGN
STRUCTURAL CONFIGURATION
LATERAL FORCE RESISTING SYSTEMS
3. In general, most earthquake code provisions require that structures be
able to resist:
1. Minor earthquakes without any damage.
2. Moderate earthquakes with negligible structural damage and some
nonstructural damage.
3. Major earthquakes with some structural and nonstructural damage
but without collapse.
The Philosophy of Seismic Design
SAMER
AKIL
4. Then, one eliminates the likelihood of inelastic action or failure
elsewhere in the structure by making the capacities of adjoining
structural members greater than that needed to reach the
maximum capacity of the inelastic zone.
In seismic design, the engineer first acknowledges that inelastic
action is unavoidable during severe earthquakes.
The designer then dictates where inelastic response should occur.
Such zones of possible inelastic action are selected to be regions
where large inelastic deformations can develop without significant
loss of strength; these regions are detailed to suppress premature
undesirable failures modes, such as member instability.
SAMER
AKIL
6. So
The Hysteretic damping: the
energy that is dissipated in every
loading cycle, due to the plastic
behaviour of the material.
By allowing yielding at
some fraction of the
elastic seismic demand,
the design forces are
reduced and the desired
economy is achieved
The structure has a lot of
reserve capacity beyond first
significant yield if the designer
detailed the structure to obtain
this type of Performance.
The design forces are much lower
than those that would be
required if the structure were to
remain elastic.
It would certainly be desirable
to design structures to remain
elastic during extreme events.
However, elastic seismic forces
can be several times the wind
force and design for such
forces is simply not
economically feasible.
There is a possibility that an
earthquake may not occur
during the life of the structure
WHY ?
+
+
SAMER
AKIL
7. Yielding of a beam section due to bending
Direct stress due to bending
Formation of a plastic hinge in a simply supported
beam
Firstly, What is Plastic Hinge ??
Stress- Strain Curve for steel
Capacity Beyond First Significant yield
SAMER
AKIL
8. R.C. Beam case ;
• At low loads the section is uncracked.
• After the concrete cracks, the concrete on the tension side of the
beam is neglected, and a cracked-transformed section analysis can be
used to predict behavior. However, this method is only valid as long as
both the steel and the concrete stress-strain behaviors are linear.
Concrete can be assumed to have a linear stress-strain behavior up to
approximately 50% of maximum concrete stress (f’c )
•After the concrete stress exceeds about 50%f’c, a strain compatibility
approach can be used, using a realistic concrete stress-strain model.
• After the steel yields,
there is typically an
extended plateau in
which the displacement
increases significantly
with very little increase
in applied load.
SAMER
AKIL
9. Load- Deflection curve for Fixed End beam
Collapse Load Vs First Yielding load ?
SAMER
AKIL
10. Frame Case
• In most structures that are subjected to moderate-to-strong
earthquakes, economical earthquake resistance is achieved by
allowing yielding to take place in some structural members.
• It is generally impractical as well as uneconomical to design a
structure to respond in the elastic range to maximum expected
earthquake-induced inertia forces.
SAMER
AKIL
11. Structures that contain facilities critical to postearthquake
operations—such as hospitals, fire stations, power plants, and
communication centers—must not only survive without collapse,
but must also remain operational after an earthquake. Therefore,
in addition to life safety, damage control is an important design
consideration for structures deemed vital to postearthquake
functions.
SAMER
AKIL
13. The test setup. A predefined cycle of
displacements is applied, and the
resisting force is monitored. The
displacement cycle is often provided
in material-specific loading protocols.
The Hysteretic damping
SAMER
AKIL
14. Example of lab test
Shear wall under reverse load
SAMER
AKIL
16. • The area contained within a single hysteresis loop is often a better
indicator of performance than is ductility. For example, each of the
structures tested have about the same overall ductility and neither
suffers appreciable strength loss.
the energy dissipated per cycle for is greater the robust system and,
hence, this system is preferable.
The more energy
dissipated per cycle
without excessive
deformation, the
better the behavior
of the structure.
SAMER
AKIL
19. Even if the motion can be predicted it is unlikely than we can
precisely predict the response. This is due to the rather long list of
things we do not know and can not do, as well as uncertainties in
the things we do know and can do.
The best we can hope for is to predict the characteristics of the
ground motion and the characteristics of the response.
It must be made very clear that the purpose of analysis is
NOT to accurately predict the response of a certain structure
to a certain ground motion. This is impossible due to the
large number of uncertainties in modeling, loading, analysis,
and interpretation of results.
What we are trying to do is to use analysis to get a handle
on the likely behavior of a structure, and to estimate
whether or not such behavior will meet pre-established
performance objectives.
The “design” ground motion cannot be predicted.
SAMER
AKIL
20. The Difference Between Wind-Resistant Design
and Earthquake-Resistant Design
• The intuitive philosophy of structural design uses force as the basis,
which is consistent in wind design, wherein the building is subjected
to a pressure on its exposed surface area; this is force-type loading.
However, in earthquake design, the building is subjected to random
motion of the ground at its base which induces inertia forces in the
building that in turn cause stresses; this is displacement-type loading.
Difference in the design effects on a building during natural actions of (a) Earthquake
Ground Movement at base, and (b) Wind Pressure on exposed area
SAMER
AKIL
21. Wind force on the building has a non-zero mean component
superposed with a relatively small oscillating component. Thus,
under wind forces, the building may experience small fluctuations in
the stress field, but reversal of stresses occurs only when the
direction of wind reverses, which happens only over a large
duration of time. On the other hand, the motion of the ground
during the earthquake is cyclic about the neutral position of the
structure. Thus, the stresses in the building due to seismic actions
undergo many complete reversals and that too over the small
duration of earthquake.
Nature of temporal variations of design actions: (a) Earthquake Ground Motion – zero
mean, cyclic, and (b) Wind Pressure – non-zero mean, oscillatory
SAMER
AKIL
22. Note that the force-displacement plot shows three points -- 10 year
wind, 50 year wind, and factored 50 year wind. The 10 year wind is
used for serviceability issues (drift) and the factored 50 year wind is
used for design (assuming strength based design). Under the
factored 50 year wind, the structure is still responding in a linear
elastic fashion. (By linear, we mean no yielding of steel or crushing of
concrete. Cracking of concrete will occur under the factored 50 year
wind (and perhaps the 10 year wind).
For most buildings, dynamic
wind response may be
neglected.
However, for very flexible
buildings and for buildings of
unusual shape, aeroelastic
interaction between the wind
load and structural response
is possible, leading to a true
dynamic response in the
structure.
SAMER
AKIL
24. The following table shows the common structural system in RC
buildings used effectively for providing resistance to seismic lateral
forces. (in Syria: shear wall system is the most common system for
buildings while frame system is used in case of special architectural
requirements, Dual system is used frequently for taller buildings (say
10 stories or more).
SAMER
AKIL
25. • A frame is considered rigid when its beam-to-column
connections have sufficient rigidity to hold virtually unchanged the
original angles between intersecting members. In buildings where
a space frame resists the earthquake forces, the columns and
beams act in bending.
• In this system, lateral loads are resisted primarily by the rigid
frame action; that is, by the development of shear forces and
bending moments in the frame members and joints.
• The continuity at both ends of beams also assists in resisting
gravity loads more efficiently by reducing positive moments in
beam spans.
• Moment frames have certain advantages in building applications
due to their flexibility in architectural planning.
1. Moment Rigid Frames
SAMER
AKIL
26. (a) Response of rigid frame to lateral loads; (b) flexural deformation of beams
and columns due to nondeformability of connections
• The strength and ductility of the connections between beams and
columns are also important considerations, particularly for frames
designed to resist seismic loads.
• The depths of frame members are often controlled by stiffness
rather than strength to limit story drift under lateral loads.
SAMER
AKIL
27. >>> FLAT SLAB-FRAME SYSTEM
• Perhaps one of the simplest framing techniques for a concrete
building consists of a two-way floor slab framing directly into
columns without beams. Although physically no beam exists
between the columns, for analytical purposes, a certain width of
slab may be considered as a beam framing between the columns.
• Particular concern in the design of a flat slab-frame is the
problem of shear stress concentration at the column–slab joint.
Shear reinforcement is necessary to improve joint behavior and
avoid early stiffness deterioration under lateral cyclic loading. This
is one of the primary reasons that two way slab systems are not
permitted by the ACI in regions of high seismic risk (UBC zones 3
and 4)
Cracking reduces the stiffness of the slab-beams. The magnitude of
the loss of stiffness will depend on the type of slab system and the
reinforcement details.
SAMER
AKIL
28. Typical floor systems for Flat slab-Frames
Flat plate/slab systems: (a) without column capitals, (b) with column capitals
SAMER
AKIL
29. 2. Shear Walls
• A shear wall building is normally more rigid than a framed
structure. With low design stress limits in shear walls, deflection
due to shear forces is relatively small.
• Notable exceptions to the
excellent performance of
shear walls occur when the
height-to-width ratio becomes
great enough to make
overturning a problem and
when there are excessive
openings in the shear walls.
• Also, if the soil beneath its
footings is relatively soft, the
entire shear wall may rotate,
causing localized damage
around the wall.
SAMER
AKIL
30. Some illustrative structural wall elevations
• Shear wall construction
is an economical method
of bracing buildings to
limit damage, and this
type of construction is
normally economically
feasible up to about 15
stories.
Various wall cross sections
SAMER
AKIL
31. >>> COUPLED SHEAR WALLS
-This system is economical for buildings
in the 40-story range.
- Since planar shear walls carry loads only
in their plane, walls in two orthogonal
directions are generally required to resist
lateral loads in two directions. resistance
to torsional loads must be considered in
determining their location
-.
Plastic Hinges occur at the end
of couplings beams then at the
base of shear walls >>>
Excellent dissipating of energy
SAMER
AKIL
32. • It is, however, difficult to define small openings quantitatively. As
a rough estimate, it can be assumed that small holes for windows
and doors are those with width ( lo ) less than 10 – 15% of the wall
length ( Lw ) . (i.e. lo / Lw < 0.10 – 0.15).
• For small openings, SWs behave like monolithic cantilever
columns; the influence of windows and doors is negligible.
Lateral load-resistance of single and coupled shear walls.
(See the behavior and design of coupled shear walls under cyclic loads in the lecture No.8)
SAMER
AKIL
33. In this system, resistance to horizontal loading is provided by a
combination of shear walls and rigid frames.
The shear walls are often placed around elevator and service cores
while the frames with relatively deep spandrels occur at the building
perimeter.
3. Shear Wall – Frame System.
Shear wall–frame interaction.
Shear walls with interior frames.
SAMER
AKIL
34. • Overall lateral deformations are primarily generated by shear
forces (frame) and flexural bending (bracing system or wall). Frame
lateral displacements reduce as the height increases; conversely,
lateral deflections of braced frames and structural walls increase
with the height.
• The net effect is that at lower storeys, bracing systems and walls
are stiffer than frames, while, in turn, the latter possess higher
stiffness at upper floors.
The potential advantages of a wall–frame structure depend on the
intensity of horizontal interaction, which is governed by the relative
stiffness of the walls and frames, and the height of the structure.
The taller the building and the stiffer the frames, the greater the
interaction.
SAMER
AKIL
35. • This difference in lateral stiffness along the height between the
structural components significantly affects the distribution of
seismic actions as shown:
SAMER
AKIL
36. In Shear Wall–Frame System:
It is observed that the total shear carried by the MRF at top storeys
can exceed the applied seismic action ‘negative storey shear share ’.
Effects of negative storey shear share are exacerbated if rotation of
the wall anchors is allowed.
Interaction between frame and structural wall
SAMER
AKIL
37. 4. BRACED FRAMES
• Generally speaking, rigid frame systems are not efficient for
buildings taller than about 20 stories because deflection due to
bending of columns and girders causes the drift to be too large.
• A braced frame improves upon the efficiency of a rigid frame by
virtually eliminating the bending of columns and girders. This is
because by adding web members such as diagonals or chevron
braces, the horizontal shear is resisted by the web.
SAMER
AKIL
38. • Braced frames may be grouped into two categories as either
Concentric Braced Frames (CBFs) or Eccentric Braced Frames (EBFs).
In CBFs, the axes of all members, that is, columns, beams, and
braces intersect at a common point such that the member forces
are axial without significant moments. On the other hand, EBFs,
utilize axis offsets to intentionally introduce flexure and shear in
preselected beam segments to increase ductility.
• CBFs are of questionable value in seismic regions because of their
poor inelastic behavior. Although moment-resistant frames exhibit
considerable energy dissipation characteristics, they are relatively
flexible when sized from strength considerations alone.
Eccentric bracing is a unique structural system that
attempts to combine the strength and stiffness of a braced
frame with the inelastic energy dissipation characteristics of
a moment frame.
SAMER
AKIL
40. 5. TRUSS MOMENT FRAMES
• Truss moment frames consist of horizontal trusses rigidly
connected to columns.
• The resistance to lateral displacement is by traditional frame
action.
• In these buildings, a
special segment of the truss
is designed to provide a
yield mechanism, while the
truss elements outside of
the special segment are
designed and detailed to
remain nominally elastic.
SAMER
AKIL
41. 6. STAGGERED TRUSS SYSTEM
• In this system, story-high trusses span in the transverse direction
between the columns at the exterior of the building.
• The floor system acts as a diaphragm transferring lateral loads in
the short direction to the trusses.
Lateral loads are thereby resisted by truss diagonals and are
transferred into direct loads in the columns. The columns therefore
receive no bending moments.
• In regions of low
seismicity, the system has
been used for buildings in
the 35- to 40-story range.
SAMER
AKIL
43. 7. FRAME TUBE SYSTEM
The term tube, in usual building terminology, suggests a system of
closely spaced columns say, (2.5–4.5 m) on center, tied together with
a relatively deep spandrel.
This system works efficiently as a hollow vertical cantilever.
SAMER
AKIL
44. What is ‘SHEAR LAG’
in tube system ??
Axial stress distribution in a square hollow
tube with and without shear lag.
• The stresses in the corner column
will be greater than those from a
pure tubular action, and those in
the inner columns will be less. The
stresses in the inner columns lag
behind those in the corner
columns, hence the term shear lag.
• Because the column stresses are
distributed less effectively than in
an ideal tube, the moment
resistance and the flexural rigidity
of a tubular building are much
less. Thus, although a framed tube
is highly efficient, it does not fully
utilize the potential stiffness and
strength of the structure because
of the effects of shear lag.
SAMER
AKIL
45. >>> TUBE - IN - TUBE SYSTEM
• In this system floor slabs, acting as horizontal rigid diaphragms, tie
exterior and interior tubes together so that they interact under
horizontal loads.
SAMER
AKIL
46. • Generally, The exterior tube resists most lateral loads in the
upper floors, while the interior tube (shear walls or braced frames)
carries most lateral loads at lower storeys.
Typical tube - in - tube system: layout ( left ) and action distribution ( right )
SAMER
AKIL
48. >>> EXTERIOR DIAGONAL TUBE
-Trussed Tube System improves
the efficiency of the framed
tube by increasing its potential
for use in taller buildings and
allowing greater spacing
between the columns.
-This is achieved by adding
diagonal bracing at the faces of
the tube to virtually eliminate
the shear lag in both the
flange and web frames.
SAMER
AKIL
50. 8. BUNDLED TUBE
-The underlying principle to achieve a
bundled tube response is to connect two or
more individual tubes into a single bundle.
-A bundled tube
typically consists of a
number of individual
tubes interconnected
to form a multicell
tube, in which the
frames in the lateral
load direction resist the
shears, while the flange
frames carry most of
the overturning
moments.
SAMER
AKIL
52. 9. THE DIAGRID FRAMED TUBE
• The diagrid-framed-tube system can be formed by using closely
spaced diagonal braces instead of vertical columns.
• This system is more effective against lateral loads than the
conventional framed-tube system. Placing the elements in a closely
spaced diagrid pattern provides sufficient resistance against vertical
and lateral loads.
• While the shear forces caused by lateral loads are met by the
bending strength of the columns and beams in the framed-tube
system, in the diagrid-framed-tube system they are met by the axial
compressive and tensile strength of the diagonal braces which
significantly increases the efficiency of the structural system.
SAMER
AKIL
56. 10. Megacolumn (mega frame, space truss) Systems
• Mega column systems consist of reinforced concrete or
composite columns and/ or shear walls with much larger cross-
sections than normal, running continuously throughout the height
of the building. In this system, mega columns and/or mega shear
walls can resist all the vertical and lateral loads.
Taipei 101, Taipei, Taiwan, 2004
SAMER
AKIL
58. 11. Mega Core Systems
• Mega core systems consist of reinforced concrete or composite
core shear walls with much larger cross-sections than normal,
running continuously throughout the height of the building.
• Since the mega core can resist all vertical and lateral loads in this
system, there is no need for columns or shear walls on the
perimeter of the building. In mega core systems, floor slabs are
cantilevered from the core shear wall.
• Mega core systems can also be used with strengthened cantilever
slabs . In this case, floor slabs are supported by the core shear
walls and discontinuous perimeter columns. Perimeter columns
are supported by strengthened cantilever slabs repeated on some
storeys. Strengthened cantilever slabs protrude from the core, and
are strengthened in order to support the load coming from the
storeys above.
SAMER
AKIL
59. Slabs in the mega core system: (a) cantilever slab, (b) supported cantilever slab
SAMER
AKIL
60. Mega core systems efficiently and economically provide sufficient
stiffness to resist wind and earthquake induced lateral loads in
buildings of more than 40 storeys.
8 Shenton Way, Singapore, 1986
SAMER
AKIL
62. 12. OUTRIGGER AND BELT WALL SYSTEM
-The structural arrangement for
this system consists of a main
concrete core connected to
exterior columns by relatively
stiff horizontal members such
as a one or two-story deep
walls commonly referred to as
outriggers.
-The core may be centrally
located with outriggers extending
on both sides or it may be located
on one side of the building with
outriggers extending to the
building columns on one side.
SAMER
AKIL
63. -The basic structural response of the system is quite simple. When
subjected to lateral loads, the column-restrained outriggers resist
the rotation of the core, causing the lateral deflections and moments
in the core to be smaller than if the freestanding core alone resisted
the loading.
SAMER
AKIL
67. STRUCTURAL CONFIGURATION
•To achieve adequate performance, basic principles recommended
to follow for ‘ conceptual design ’ are provided here, which can be
summarized below:
(i) Simplicity: consists of clear and direct paths for vertical and
horizontal forces due to the combination of gravity and earthquake
loading.
(ii) Uniformity: uniform distribution of structural elements in plan
and elevation, allowing for smooth and direct transmission of the
inertial forces generated by the masses of structural and non -
structural components. Concentrations of stresses or large ductility
demands cause premature collapse. It may be necessary to
subdivide the entire building into independent units by using
seismic joints.
SAMER
AKIL
68. (iii) Symmetry: symmetrical or quasi - symmetrical structural layouts,
well distributed in - plan, are a viable solution for the achievement of
uniformity. Structural symmetry means that the centre of mass and
centre of resistance are located at, or close to, the same point.
Eccentricity produces torsion and stress concentrations.
(iv) Redundancy: this is a measure of the degree of indeterminacy
and reliability of structural systems. Redundancy primarily arises
from the capacity of structures to provide an alternative loading
path after any component failure.
(v) Bidirectional resistance and stiffness: lateral resisting elements
and systems arranged in an orthogonal in - plan pattern provide
similar resistance and stiffness characteristics in the principal
directions of the structure. High horizontal stiffness is effective in
limiting excessive displacements that may lead to instabilities (e.g.
due to P - Δ effects) or to extensive structural and non - structural
damage.
SAMER
AKIL
69. (vi) Torsional resistance and stiffness: adequate torsional stiffness
and resistance is necessary to reduce torsional motions which tend
to stress the structural elements non - uniformly. In this respect,
arrangements in which the main elements resisting the seismic
actions are distributed close to the periphery of the building
present clear advantages.
(vii) Diaphragm behaviour at storey level: floor and roof systems act
as horizontal diaphragms in building structures. These collect and
transmit inertia forces to the vertical elements of lateral resistant
systems, i.e. columns and structural walls. They also ensure that
vertical components act together under gravity and seismic loads.
(viii) Adequate foundation: stiff and resistant foundations and their
connections with the superstructure ensure that the whole structure
is subjected to uniform seismic excitation. Buildings with isolated
foundation elements should utilize a foundation slab or tie beams
between these elements in both main directions.
SAMER
AKIL
70. • Typical building configuration deficiencies include an irregular
geometry, a weakness in a story, a concentration of mass, or a
discontinuity in the lateral-force-resisting system. Vertical irregularities
are defined in terms of strength, stiffness, geometry, and mass.
• When irregular features are unavoidable, special design
considerations are required to account for the unusual dynamic
characteristics and the load transfer and stress concentrations that
occur at abrupt changes in structural resistance.
SAMER
AKIL
71. TORSION
• if the Centre of Mass (CoM) of a building is not coincident with
the Centre of Resistance (CoR) a torsional moment acts in the
horizontal plane causing floor diaphragms to twist about the CoR.
SAMER
AKIL
72. • Engineers prevent building
damage arising from torsion by
using several approaches. Firstly,
they minimize the distance in
plan between the CoM and CoR.
Remember that even with a
perfectly symmetrical structural
configuration some degree of
torsion still occurs due to
torsional motions within the
ground shaking.
• Secondly, designers provide a
minimum of two lines of vertical
structure parallel to each of the
main orthogonal axes of a
building horizontally offset from
each other.
SAMER
AKIL
73. Also due to the diaphragm rotation, the x direction shear walls
deflect horizontally Δx in opposite directions. Like the y direction
shear walls, they react against the movement that deflects them.
They apply equal and opposite reaction forces upon the diaphragm
creating another moment couple. Even though no x direction seismic
forces act on the building, because these two shear walls orientated
parallel to the x axis are strongly connected to the diaphragm, they
nonetheless participate in resisting torsion.
SAMER
AKIL
74. The four extra shear walls added in plan (a) enhance torsional
resistance slightly. Even if the new walls are identical to the
perimeter walls because they are closer to the CoR they are subject
to 50 per cent smaller displacements when the diaphragm twists
and the leverarms between them are less. With a lesser resisting
force (proportional to horizontal displacement) and half the lever
arm their torsion-resisting contribution is only 25 per cent of that
provided by the perimeter walls.
SAMER
AKIL
75. • If the perimeter walls are
removed, and horizontal forces
and torsion are now resisted by
the inner walls alone, the two
torsion-resisting couples must
offer the same resistance as
before since the value of the
torsion moment is unchanged.
• Although the previous figures illustrate shear walls resisting seismic
forces, moment and braced frames can also provide adequate
torsion resistance. Replace the shear walls with one- or multi-bay
moment frames and the principles outlined above still apply. The
building will be less torsionally stiff due to the lesser stiffness of the
frames but still perform adequately, especially if the frames are
located on the perimeter of the building.
SAMER
AKIL
76. In the examples considered so far, a recommended torsion-resistant
structure comprises a minimum of four vertical elements, like shear
walls or moment frames, with two in each direction. However, in
some situations the number of elements can be reduced to three
Any y direction forces are resisted by one
shear wall, and x direction forces resisted
by two walls. When torsion induces
diaphragm rotation, the two x direction
walls, in this case with a long lever-arm
between them, form a moment couple.
They provide torsional stability or
equilibrium irrespective of the direction of
loading – but only so long as they remain
elastic. Most shear walls and frames are
designed for relatively low seismic forces if
they incorporate ductile detailing >>>
SAMER
AKIL
77. >>> So when one x direction wall yields as a result of inertia forces
in the x direction as well as torsion it temporarily loses its stiffness
and the CoR migrates towards the stiffer end, increasing torsional
eccentricity. The system becomes torsionally unstable.
This configuration consisting of three vertical structural
elements is described by structural engineers as a torsionally
unbalanced system. It is not recommended unless the x
direction walls or frames are much stronger than minimum
requirements. They must be capable of resisting horizontal
forces with little or no ductility demand and therefore possibly
possess far more strength than normal.
• Until research findings update guidelines, architects should
avoid torsionally unbalanced systems unless satisfying the
criterion above.
SAMER
AKIL
78. RE-ENTRANT CORNERS
Many buildings have
suffered seismic damage
due to re-entrant corners
in past earthquake.
Although re-entrant
geometries can take many
shapes, what they share
in common from a seismic
design perspective, is
their potential for
damage resulting from
the different dynamic
properties of each wing.
Typical re-entrant corner forms.
SAMER
AKIL
79. For example, when the building in
the right Fig is shaken in the
y direction, the left-hand area of the
building, and the wing to the right,
react quite differently. The left-hand
area deflects horizontally a relatively
small amount due to its greater
depth and inherently greater
horizontal stiffness.
The more flexible wing moves
further and at a different period of
vibration. It swings about the stiffer
area, possibly damaging floor
diaphragms at the junction of the
two wings.
SAMER
AKIL
80. • The attitude of most codes towards re-entrant corners is to require
structural engineers to undertake a 3–D dynamic analysis where
the length of a projecting area of building causing a re-entrant corner
exceeds approximately 15 percent of the building plan dimension.
• An engineer will design the re-
entrant structure to avoid either
diaphragm tearing or excessive
horizontal deflections.
• However, if they are long or
their diaphragms weakened by
penetrations for vertical
circulation or other reasons in
the critical region where they
join, that approach may not be
structurally sound. The building
might best be separated into
two independent structures. Irregular plan configurations
improved by seismic separation gaps.
SAMER
AKIL
81. Two methods of supporting flooring
at a seismic separation gap.
Possible detail of a seismic separation gap
between two buildings at roof level
A section through a generic
floor level seismic gap.
SAMER
AKIL
82. DIAPHRAGM DISCONTINUITIES
• In most buildings quite large penetrations are required for vertical
circulation such as stairways and elevators. Building services,
including air ducts and pipes also need to pass through floor slabs
and in the process introduce potential weaknesses into diaphragms.
• It likens diaphragms to horizontal beams resisting and transferring
horizontal inertia forces to their supports which, in this case, consist
of vertical structural systems such as shear walls or moment frames.
A slot in the diaphragm destroys its ability to span between shear
walls for y direction forces. (X direction structure not shown.)
SAMER
AKIL
83. • The web of a diaphragm resists shear forces, while perimeter
diaphragm chords acting in tension or compression, resist bending
moments.
Inertia forces within a multi-storey building
shown in plan and section
SAMER
AKIL
85. Where the length of a bracing
element – such as a shear
wall – is short in plan with
respect to the width of the
diaphragm transferring forces
into it, the interface between
the horizontal and vertical
element may be too weak to
transfer the forces between
them. In this case, a
‘collector’ or tie member is
required. It collects forces
from the diaphragm acting in
either tension or
compression, depending
upon the direction of force at
that instant of time and
transfers them into the wall.
Collector or tie members transfer
diaphragm shear forces into vertical structure
SAMER
AKIL
86. • The size of a penetration can be large enough to ruin the structural
integrity of a diaphragm altogether.
• Consider the case of a simple rectangular diaphragm spanning
between two shear walls that act in the y direction, What are the
structural options if a full-width slot is required?
The slot destroys the ability of the diaphragm to span to the right-
hand wall. If the purpose of the slot is to introduce light or services
through the diaphragm one option is to bridge the slot by
introducing a section of steel bracing.
SAMER
AKIL
87. Alternatively, if the geometry of diagonal members isn’t acceptable
aesthetically a horizontal vierendeel frame, with its far larger
member sizes, can be inserted to restore structural function
If the intention of the
penetration is to provide a
staircase. The only option is
to no longer consider that
wall as a shear wall but to
provide a new shear wall to
the left of the penetration.
SAMER
AKIL
88. A serious diaphragm
discontinuity occurs where a
potential floor diaphragm
consists of more than one
level. If a relatively small area
is raised or lowered it can be
treated, as far as seismic
behaviour is concerned, as if
it were a penetration.
A stepped diaphragm.
A kinked beam showing internal
compression and tension forces that can
not be achieved.
SAMER
AKIL
89. • Two ways to overcome these problems are; firstly, to fully
separate the building into two structures as discussed previously;
or secondly, to introduce a shear wall or frame along the line of the
step and provide x direction shear walls at each end of the building.
If the step is higher than several hundred millimetres, one
diaphragm will apply y direction forces directly to the columns of
the centre frame. This could lead to their premature failure and so
the best approach would be to separate the diaphragms and their
supporting members into two independent structures.
SAMER
AKIL
90. Plan irregularities:
(b) irregularity due
to mass-resistance
eccentricity;
(c) irregularity due
to discontinuity in
diaphragm stiffness.
Unfavourable core
arrangement;
diaphragm at risk
due to shear failure
at the connections
to the cores.
SAMER
AKIL
91. NON-PARALLEL SYSTEMS
The following figure illustrates two
non-parallel systems. In each case
the directions of strength of the
vertical structures are angled with
respect to any sets of orthogonal
axes.
Two examples of non-parallel
systems. Gravity-only structure not shown
The ability of each configuration
to resist horizontal forces and
torsion is understood by
considering the length of each
vertical system as a strength
vector. A vector can be resolved
into components parallel to, and
normal to, a set of axes.
SAMER
AKIL
92. In the symmetrically configured
building, as the shear walls resist
y direction forces, the
diaphragms must provide tension
and compression forces to keep
the system stable. When the
configuration of non-parallel
systems is asymmetrical the
distribution of these internal
forces becomes far more
complex. For this reason codes
insist that structural engineers
model non-parallel systems in
3–D in order to capture these
effects and design for them. A non-parallel system showing the
orthogonal force components of each wall
and secondary diaphragm stresses for a y
direction force.
SAMER
AKIL
93. SOFT STOREYS
Soft storey configuration describes structure where one storey of a
building is more flexible and/or weaker than the one above it from
the perspective of seismic forces.
Rather than earthquake energy
absorbed by ductile yielding of
steel reinforcing bars, or
structural steel sections in plastic
hinge zones, or structural fuses
throughout the whole structure
as shown in Fig. (b), in a soft
storey configuration earthquake
energy concentrates on the soft
storey. Serious damage is caused
especially to the columns of that
soft storey.
SAMER
AKIL
94. A collapsed building with weak
columns and strong beams. 1985
Mexico earthquake.
A soft storey building is doomed,
since columns in the soft storey
usually lack the resilience to
absorb seismic damage and still
continue to support the weight of
the building above.
Of all vertical configuration
problems, the soft storey is the
most serious and is by far the
most prevalent reason for multi-
storey building collapses. So many
buildings, located in seismically
active regions throughout the
world possess relatively open
ground floors and are at risk of a
soft storey mechanism forming.
SAMER
AKIL
95. Soft storeys are also caused by other configuration irregularities as
illustrated in the next figure.
Examples of soft storey configurations.
if the soft storey irregularity is reasonably minor, a seismic code may
permit the system to resist horizontal forces. However, the structural
engineer must undertake special analyses and provide members
within that storey with additional strength and ductile detailing.
SAMER
AKIL
96. So the questions arise:
‘ Is it possible for a building to exhibit the visual characteristics of a
soft storey for architectural reasons and still perform satisfactorily
in a quake; and if so, how? ’
Let’s take some real examples :
In more severe soft storey cases even the most advanced structural
design cannot prevent poor performance in a design-level
earthquake.
SAMER
AKIL
97. Imagine that you are designing a building whose façade is
modulated by slender columns and deep beams (see next Fig.).
How can you achieve this presumably architecturally desirable
layout without creating a hazardous weak column–strong beam
configuration?
A weak column–strong beam structure
develops a soft storey at ground level once
columns are damaged.
SAMER
AKIL
98. One of two strategies is employed:
>> either separation or differentiation.
• Separation involves isolating from the
force path those stiff and strong
elements – like infill walls and deep
beams – which cause adjacent
elements – like columns – to be
relatively more flexible and weaker.
• If, for any reason the strategy of
separation is unacceptable, then
consider differentiation as a solution. In
this approach the seismically flawed
frame configuration remains on the
façade but is relieved of any
expectation of withstanding horizontal
forces by provision of an alternative
and stiffer system elsewhere in plan.
SAMER
AKIL
99. The internal moment frames
and shear walls of the next Fig.
resist all horizontal forces
because they are stiffer and
stronger. They are designed so
as the perimeter frames need
only carry gravity forces.
Whether or not that
intentional softening is
undertaken the perimeter
frame must be flexible and
possibly possess some
ductility. It has to undergo the
same horizontal drifts as the
stronger alternative seismic
resisting structure without
distress while, at the same
time, resisting gravity forces.
SAMER
AKIL
100. What if, you require a double-height floor at ground floor level, or
anywhere else up the height of a building for that matter?
Begin by accepting that the frames with such a flexible and soft
storey must be excluded from the primary seismic resisting system.
So keep their irregular configuration and design them to resist gravity
forces only. Once again provide an alternative stiffer structure to
resist all seismic forces. At least two other approaches are possible.
First, introduce beams without floor
slabs . This may achieve the intended
spaciousness of the double-height
storey yet avoid a soft storey by
restoring the regularity of the
moment frame. Now that the weight
of the level without a floor is far less
than that of the floor above, a special
engineering analysis and design is
required.
(a) Provided beams
without slabs
SAMER
AKIL
101. The main disadvantage of the
mega-frame solution is that
the frame member sizes are
considerably larger than
normal in order to control the
increased drift and bending
and shear stresses due to the
increased storey heights. The
columns must also be
designed to resist mid-height
inertia forces acting at
alternate storeys.
(b) Create a two-storey mega-frame by pinning
the ends of beams on alternate storeys
If the idea of inserting beams to create regularity is unattractive,
consider a mega-frame solution. The moment frame storey height is
extended to two storeys. At alternate storeys floor beams are pinned
at their ends to prevent them participating as moment frame
elements.
SAMER
AKIL
102. SHORT COLUMNS
• Short columns are to be avoided just
as assiduously as flexible columns.
• There are two types of short
column problems;
firstly, where some columns are
shorter than others in a moment
frame, and
secondly, where columns are so
short they are inherently brittle.
• The stiffness of a column against a
horizontal force is extremely sensitive
to its length; in fact, inversely
proportional to the column length
cubed (L3). Examples of short columns among
longer columns of moment frames
SAMER
AKIL
103. In following Fig. Two
columns together, one
that is half the height of
the other, resist a
horizontal force. The
shorter column is
therefore eight times
stiffer than the other, so
it tries to resist almost
eight times as much
force as the longer
column. It is unlikely to
be strong enough to
resist such a large
proportion of the
horizontal force and
may fail.
Two unequal height columns resisting seismic force.
SAMER
AKIL
104. This type of short column problem can be overcome in several ways:
• If the beams that frame into the
columns forming short columns (in the
next Fig.) are pinned at both ends, that
effectively doubles the column lengths
and makes them all of equal length as far
as seismic resistance is concerned. Of
course, that creates a soft storey scenario
that then needs to be addressed.
• An alternative approach to structuring is to neglect the seismic
strength of the long columns altogether and to resist all seismic
forces by four one-bay frames; two acting in each direction to
achieve a symmetrical structural configuration.
SAMER
AKIL
105. • On a sloping site, short columns can be lengthened by integrating
them with the piles . If the piles are monolithic with columns and
protected from contact with the ground by sleeves or casings that
allow unrestrained horizontal drift, then a short column is avoided.
Finally, check that a soft storey does not result from this foundation
modification.
A method of avoiding a short column on a sloping site
SAMER
AKIL
106. Comparison between a regular and a short
column subject to horizontal drift.
Now we return to short
columns which have a
very short distance over
which they can flex
horizontally.
short column has an
unrestrained or free-
length less that twice its
depth. The problem is
that the free-length is too
short to allow for the
development of a ductile
plastic hinges.
In the event of seismic
overload the column fails
in shear.
SAMER
AKIL
107. • One solution is to avoid
them. by confined
masonry or structural
masonry walls to function
as shear walls and the
masonry is partial height,
• Guevara and Garc´ia
suggest continuing a short
length of masonry up the
sides of columns so that
diagonal compression
struts can act at the beam-
column joint and thereby
avoid short column failure
Reduction in the width of an opening
above a partial-height masonry.
SAMER
AKIL
108. • Another solution is to
separate that masonry
infills to prevent short
column configuration.
Methods to avoid a short column configuration
with reinforced concrete infills.
• The same approach
applies if infill walls are of
reinforced concrete
construction.
• Alternatively, designers
can infill one or more
windows to form shear
walls which are strong
and stiff enough to resist
seismic forces without
short columns being
damaged.
SAMER
AKIL
109. Short column failure. 2007, Peru earthquake.
Typical short column damage. 1994 Northridge
Note that even if strong infills are
separated from the moment frame
as shown, the ductility of the frame
is reduced due to the stiffening
and strengthening effect the infills
have on the beams. The beams
cannot bend when the building
sways.
SAMER
AKIL
110. Members reinforced conventionally,
have substantially different
behaviour under cyclic loading
characterised by a high vulnerability
to brittle failure in a mode of x-
shaped diagonal splitting of concrete
due to a diagonal compressive field
leading to a premature explosive
cleavage shear fracture.
alternative arrangements of
reinforcement were proposed
aiming at the improvement of the
behaviour of short columns under
seismic action and especially
aiming at avoiding premature
explosive cleavage fracture.
See Lecture No (7) later for
more details
SAMER
AKIL
111. DISCONTINUOUS AND OFF-SET WALLS
Consider the building in next Fig.
At its upper levels y direction
forces are resisted by shear walls
at each end, but at ground floor
level the left-hand wall, Wall 1, is
discontinuous.
SAMER
AKIL
112. • Two perimeter moment frames resist x direction forces. When
struck by a quake in the y direction, the ground pulses will distort
the ground floor columns under Wall 1. Their ‘softness’ prevents
Wall 1 from providing the seismic resistance perhaps expected of it
and exemplifies the worst possible case of a soft storey.
• At the other end of the building the base of Wall 2, which is
continuous, moves with the ground motion. Due to the more
substantial overall strength and stiffness of Wall 2, as compared to
Wall 1, Wall 2 tends to resist the inertia forces from the whole
building.
Since Wall 1 resists almost no inertia force due to its discontinuity,
yet Wall 2 is fully functional the building experiences serious
torsion. To some degree, but limited by the modest lever-arm
between them and their inherent flexibility, the two x direction
moment frames try to resist the torsion. As the building twists
about its CoR located close to Wall 2, the columns furthest away
from the CoR are subject to large drifts and severe damage.
SAMER
AKIL
113. Two strong columns, one at each end of Wall 1 must withstand vertical
tension and compression forces.
See Lecture No (8) later
for more details about
design of shear walls.
SAMER
AKIL
114. • if those columns under
Wall 1 are omitted, the
overturning-induced axial
force can also be resisted
by two deep transfer
trusses or beams. They
must remain elastic
during the design level
quake to prevent
permanent downwards
movement of the wall.
Alternatives to a discontinuous wall.
• Another possibility is to
introduce an off-set
single-storey wall back
from Wall 1 ( Fig. (b) ).
SAMER
AKIL
115. Since the trusses or deep beams create a strong beam–weak
column configuration, ground floor shear walls in the x direction will
be required as well as the whole of the first floor slab being
designed as a transfer diaphragm. Another reason the offset
solution is not ideal is that torsion is introduced due to eccentricity
between the CoM and CoR at ground floor level for y direction
forces.
The danger posed by off-set walls supported on cantilever beams
has been tragically and repeatedly observed during five Turkish
earthquakes in the 1990. After categorizing building damage a
report concludes:
‘Buildings having architecturally based irregular structural systems
were heavily damaged or collapsed during the earthquake.
Cantilevers of irregular buildings have again proven to be the
primary source/cause of seismic damage. Many buildings have
regular structural systems but [even if] roughly designed
performed well with minor damage ’ .
SAMER
AKIL
116. The next figure shows a less
extreme wall discontinuity.
A large penetration
weakens the most highly
stressed region of the wall
creating an undesirable soft
storey.
Traditional engineering
wisdom would advise
designing the wall to be
nonstructural, but given the
sophisticated 3-D analysis
and design tools available
to contemporary structural
engineers, a careful design
might achieve satisfactory
seismic performance. A partially discontinuous wall and options for the
location of its structural fuse ormplastic hinge region.
SAMER
AKIL
117. When approaching the design of an element with a discontinuity
such as this, it is crucial that designers first identify the ductile
overload mechanism ( Fig. (b) or (c) ), and then using the Capacity
Design approach, ensure dependable ductile behaviour.
One approach is to design for plastic hinging at ground floor level
and detail the wall and unattached column accordingly with the
wall above strengthened to avoid premature damage.
Another approach is for the first floor section of wall to be
designated the fuse region. This means the ground floor section
and the wall above first floor will be stronger than the fuse
so damage occurs only in that specially detailed area.
SAMER
AKIL
118. SETBACKS
• A setback is where a plan
dimension of a storey above
a certain level in a multi-
storey building reduces.
• Sophisticated structural
analyses quantify the ‘notch
effect ’ of a setback, but even
though structural engineers
avoid notches wherever
possible because of stress
concentrations, setbacks can
be designed satisfactorily.
Typical setback configurations.
SAMER
AKIL
119. The podium and tower form
represents a rather severe setback
configuration. Designers are faced with
several choices. They can treat the
building as one structure. In this case,
the podium roof is probably designed
as a transfer diaphragm to force the
podium framing to contribute to the
horizontal force resistance at the
bottom storey of the building .
Alternatively, designers can provide
the podium with little if any horizontal
resistance and tie it strongly to the
primary structure of the main tower,
which then resists the seismic force of
the entire building.
Finally, the podium can be seismically
separated from the tower.
SAMER
AKIL
120. INFILL WALLS
• Infill walls are non-structural walls constructed between columns.
• Although they are not designed to resist either gravity or
horizontal forces no one has informed them! By virtue of their
inherent in-plane strength and stiffness they cannot avoid resisting
forces even if they wanted to.
• Infill walls can helpfully resist seismic forces in buildings, but only
in certain situations. These include where there is no other seismic
resisting system provided; the building is low-rise; the masonry
panels are continuous from foundation to roof; there are enough
panels in each plan orthogonal direction to adequately brace the
building; the infills are not heavily penetrated; and finally, where
infill walls are placed reasonably symmetrically in plan. Most infill
walls do not satisfy these criteria and may introduce configuration
deficiencies
SAMER
AKIL
121. So what are the difficulties with infill walls given that they are
commonly used in so many countries? Why do they require special
attention in seismically active regions?
• Firstly, infill walls stiffen a building against horizontal forces
additional stiffness reduces the natural period of vibration, which
in turn leads to increased accelerations and inertia forces
• Secondly, an infill wall prevents a structural frame from freely
deflecting sideways. In the process the infill suffers damage and
may damage the surrounding frame. The in-plane stiffness of a
masonry infill wall is usually far greater than that of its surrounding
moment frame – by up to five to ten times!
• The final problem associated with the seismic performance and
influence of infill walls is that of torsion. Unless infill walls are
symmetrically placed in plan their high stiffness against seismic
force changes the location of the Centre of Resistance (CoR).
SAMER
AKIL
123. Solutions to problems caused by infill walls : three solutions are
available: the first is often not feasible and the other two, while
simple in theory, are difficult to achieve in practice.
The first solution is for infill walls to be transformed into
confined masonry construction that is fully integrated with the
structural frame.
Another alternative is to provide very stiff primary structure
(RC shear walls). In this situation the less stiff infill walls do not
attract horizontal forces.
The final option is to separate infill walls from their frames by
gaps of sufficient width as calculated by the structural engineer.
SAMER
AKIL
125. Two possible structural
details
that resist out-of-plane
forces yet allow
relative movement
between an infill wall
and structure above.
Separated unreinforced
masonry infill wall with
‘practical columns ’ providing
out-of-plane strength.
SAMER
AKIL