1) A pushover analysis is a nonlinear static analysis that estimates the strength capacity of a structure beyond its limit state up to ultimate strength. It can identify weak areas and failure mechanisms.
2) The analysis involves creating a nonlinear model of the structure with hinges at locations of expected inelastic behavior. The model is pushed monotonically with a predefined lateral load pattern.
3) The results are a base shear vs. roof displacement curve and conversion to an equivalent single-degree-of-freedom system for comparison to seismic demand.
The Pushover Analysis from basics - Rahul LeslieRahul Leslie
Pushover analysis has been in the academic-research arena for quite long. The papers published in this field usually deals mostly with proposed improvements to the approach, expecting the reader to know the basics of the topic... while the common structural design practitioner, not knowing the basics, is left out from participating in those discussions. Here I’m making an effort to bridge that gap by explaining the Pushover analysis, from basics, in its simplicity.
A write up on this topic can be found at http://rahulleslie.blogspot.in/p/blog-page.html, though does not cover the full spectrum presented in this slide show.
Performance of Flat Slab Structure Using Pushover AnalysisIOSR Journals
Performance Based Seismic Engineering is the modern approach to earthquake resistant design. It
is a limit-state based design approach extended to cover complex range of issues faced by structural engineers.
Flat slabs are becoming popular and gaining importance as they are economical as compared to beam-column
connections in conventional slab. Many existing flat slabs may not have been designed for seismic forces so it is
important to study their response under seismic conditions and to evaluate seismic retrofit schemes. In this
paper we have discussed the results obtained by performing push over analysis on flat slabs by using most
common software SAP2000. A (G+7) frame having 5 bays is considered for analysis. It is observed that the
performance point of flat slab is more as compared to conventional building.
Non Linear Analysis of RCC Building with and Without Shear WallIRJET Journal
This document discusses performing non-linear static (pushover) analysis on reinforced concrete (RC) buildings both with and without shear walls. The analysis is conducted using ETABS software to obtain pushover curves and compare the displacement and base shear in the frames. The objectives are to analyze RC structures with or without shear walls, perform linear and non-linear analysis, and study how parameters like story drift, displacement, and forces are affected by the presence of shear walls. The methodology describes performing linear static analysis, dynamic analysis, and non-linear static pushover analysis on the structures.
Non Linear Static Analysis of Dual RC Frame StructureIRJET Journal
This document discusses a non-linear static (pushover) analysis of a 10-story dual reinforced concrete frame structure. A dual system uses both special moment frames and shear walls as lateral load resisting systems. The analysis develops capacity and demand curves to evaluate the structure's performance at different damage states under increasing seismic loads. The analysis is performed using ETABS software to model the nonlinear behavior and hinge properties of the frame elements. The results provide insight into how dual reinforced concrete frame systems perform seismic forces compared to bare frames.
Investigation on performance based non linear pushover analysis of flat plate...Yousuf Dinar
This document summarizes an investigation into the performance of flat plate reinforced concrete buildings under nonlinear pushover analysis. The study evaluates bare frame structures with different percentages of masonry infill, as well as structures with soft stories or shear walls. Pushover analysis was performed on a 7-story model building to determine base shear, displacement, story drift, and hinge formation at different performance levels. Results show that infill and shear walls improve seismic performance by reducing displacement, and that placing soft stories higher in the structure increases strength and stability. Shear walls performed best and controlled hinge formation, indicating more uniform response.
Performance Based Design Presentation By Deepak BashettyDeepak Bashetty
This document provides an overview of a performance-based seismic analysis conducted on a reinforced concrete building. It describes the modeling approach used, which involved defining plastic hinges in beams and columns to capture nonlinear behavior. Both pushover analysis and time history analysis were performed. The pushover analysis generated a capacity curve and identified performance points for two performance levels under the design basis earthquake and maximum considered earthquake. Time history analysis involved applying 7 sets of ground motion records scaled to target displacements. Results from the nonlinear analyses were used to evaluate response parameters like base shear, roof displacement, and interstory drift ratios to assess the building's performance.
IRJET- Progrssive Collapse Analysis of RCC Stucture for Variable Heights on S...IRJET Journal
This document presents a study on analyzing the progressive collapse potential of reinforced concrete (RC) framed buildings of heights G+5, G+10, and G+15 constructed on sloping ground. The study uses the General Service Administration (GSA) 2016 guidelines to perform linear static analysis by removing columns and calculating demand capacity ratios. Models of the buildings are generated in ETABS software considering sloping ground angles of 0°, 10°, 20°, and 30°. Analysis shows that demand capacity ratios obtained are within acceptable limits, indicating no progressive collapse occurs. Storey displacements are also compared for plain and sloping ground conditions. The study concludes bending moments in adjacent members increase after column removal but demand capacity ratios remain below specified limits as per
IRJET- Pushover Analysis on Reinforced Concrete Building using ETABSIRJET Journal
This document presents the results of a pushover analysis conducted on a 10-story reinforced concrete building modelled in ETABS to investigate the impact of using cracked versus uncracked section properties. Three cases were analyzed using different moment of inertia values to represent uncracked (1.0), partially cracked (0.7) and fully cracked (0.35) sections. The pushover curves showed that using cracked section properties resulted in lower base shear and displacement capacity compared to the uncracked model. The cracked section models more accurately represent the actual response and capacity of existing buildings that have developed cracks due to service loads. Accounting for cracked section properties is important for performance-based design.
The Pushover Analysis from basics - Rahul LeslieRahul Leslie
Pushover analysis has been in the academic-research arena for quite long. The papers published in this field usually deals mostly with proposed improvements to the approach, expecting the reader to know the basics of the topic... while the common structural design practitioner, not knowing the basics, is left out from participating in those discussions. Here I’m making an effort to bridge that gap by explaining the Pushover analysis, from basics, in its simplicity.
A write up on this topic can be found at http://rahulleslie.blogspot.in/p/blog-page.html, though does not cover the full spectrum presented in this slide show.
Performance of Flat Slab Structure Using Pushover AnalysisIOSR Journals
Performance Based Seismic Engineering is the modern approach to earthquake resistant design. It
is a limit-state based design approach extended to cover complex range of issues faced by structural engineers.
Flat slabs are becoming popular and gaining importance as they are economical as compared to beam-column
connections in conventional slab. Many existing flat slabs may not have been designed for seismic forces so it is
important to study their response under seismic conditions and to evaluate seismic retrofit schemes. In this
paper we have discussed the results obtained by performing push over analysis on flat slabs by using most
common software SAP2000. A (G+7) frame having 5 bays is considered for analysis. It is observed that the
performance point of flat slab is more as compared to conventional building.
Non Linear Analysis of RCC Building with and Without Shear WallIRJET Journal
This document discusses performing non-linear static (pushover) analysis on reinforced concrete (RC) buildings both with and without shear walls. The analysis is conducted using ETABS software to obtain pushover curves and compare the displacement and base shear in the frames. The objectives are to analyze RC structures with or without shear walls, perform linear and non-linear analysis, and study how parameters like story drift, displacement, and forces are affected by the presence of shear walls. The methodology describes performing linear static analysis, dynamic analysis, and non-linear static pushover analysis on the structures.
Non Linear Static Analysis of Dual RC Frame StructureIRJET Journal
This document discusses a non-linear static (pushover) analysis of a 10-story dual reinforced concrete frame structure. A dual system uses both special moment frames and shear walls as lateral load resisting systems. The analysis develops capacity and demand curves to evaluate the structure's performance at different damage states under increasing seismic loads. The analysis is performed using ETABS software to model the nonlinear behavior and hinge properties of the frame elements. The results provide insight into how dual reinforced concrete frame systems perform seismic forces compared to bare frames.
Investigation on performance based non linear pushover analysis of flat plate...Yousuf Dinar
This document summarizes an investigation into the performance of flat plate reinforced concrete buildings under nonlinear pushover analysis. The study evaluates bare frame structures with different percentages of masonry infill, as well as structures with soft stories or shear walls. Pushover analysis was performed on a 7-story model building to determine base shear, displacement, story drift, and hinge formation at different performance levels. Results show that infill and shear walls improve seismic performance by reducing displacement, and that placing soft stories higher in the structure increases strength and stability. Shear walls performed best and controlled hinge formation, indicating more uniform response.
Performance Based Design Presentation By Deepak BashettyDeepak Bashetty
This document provides an overview of a performance-based seismic analysis conducted on a reinforced concrete building. It describes the modeling approach used, which involved defining plastic hinges in beams and columns to capture nonlinear behavior. Both pushover analysis and time history analysis were performed. The pushover analysis generated a capacity curve and identified performance points for two performance levels under the design basis earthquake and maximum considered earthquake. Time history analysis involved applying 7 sets of ground motion records scaled to target displacements. Results from the nonlinear analyses were used to evaluate response parameters like base shear, roof displacement, and interstory drift ratios to assess the building's performance.
IRJET- Progrssive Collapse Analysis of RCC Stucture for Variable Heights on S...IRJET Journal
This document presents a study on analyzing the progressive collapse potential of reinforced concrete (RC) framed buildings of heights G+5, G+10, and G+15 constructed on sloping ground. The study uses the General Service Administration (GSA) 2016 guidelines to perform linear static analysis by removing columns and calculating demand capacity ratios. Models of the buildings are generated in ETABS software considering sloping ground angles of 0°, 10°, 20°, and 30°. Analysis shows that demand capacity ratios obtained are within acceptable limits, indicating no progressive collapse occurs. Storey displacements are also compared for plain and sloping ground conditions. The study concludes bending moments in adjacent members increase after column removal but demand capacity ratios remain below specified limits as per
IRJET- Pushover Analysis on Reinforced Concrete Building using ETABSIRJET Journal
This document presents the results of a pushover analysis conducted on a 10-story reinforced concrete building modelled in ETABS to investigate the impact of using cracked versus uncracked section properties. Three cases were analyzed using different moment of inertia values to represent uncracked (1.0), partially cracked (0.7) and fully cracked (0.35) sections. The pushover curves showed that using cracked section properties resulted in lower base shear and displacement capacity compared to the uncracked model. The cracked section models more accurately represent the actual response and capacity of existing buildings that have developed cracks due to service loads. Accounting for cracked section properties is important for performance-based design.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
IRJET- Comparative Study on Conventional Slab and Flat Slabs RCC Structure us...IRJET Journal
This document discusses a comparative study on the seismic performance of conventional slab reinforced concrete (RCC) structures and flat slab RCC structures using pushover analysis. It aims to compare the structures' behavior under parameters like base shear, story displacement, and story drift. The study finds that under equivalent pushover analysis, the conventional slab RCC structure performs better with lower base shear, story drift, and story displacement values compared to flat slab and flat plate RCC structures. Overall, the conventional slab structure is considered more seismically efficient. The document provides background on pushover analysis methodology and outlines the objectives to explore and compare the seismic behavior of different slab RCC structures through nonlinear static analysis.
Effect of soft storeys in earthquake resistant analysis of rc framed structureseSAT Journals
storey in which the stiffness is less than 70% of the storey above or less
than 80% of the combined stiffnesses of the three storeys above. It is the general practice in the multistoreyed buildings to
accommodate parking facilities for the vehicles of the occupants of the building. As we know that the soft storey in a building
structure causes stiffness irregularity in a structure, due to this the structure undergoes unequal storey drifts, formation of the
plastic hinges and then finally resulting into the collapse of the structure.This research work purely interacts with the effect of the
soft storeys in the analysis of RC framed structures as entitled above, and in this work the soft storeys positions has been provided
at different levels as shown in the analytical modelling. All the models are analyzed by using the ETABS software. The seismic
analysis performed consists of the Equivalent static analysis (ESA), response spectrum analysis (RSA), and the push over analysis
(PA). The seismic base shear forces, storey drifts, and the displacements has been compared with the three analysis methods as
listed above. With the aid of the push over analysis the values of the ductility and the response reduction factor have been
obtained. Apart from these, the performance point parameters such as spectral acceleration(Sa) , spectral displacement (Sd),
Base shear(V) and the roof displacement(D) has been also illustrated in this work and a detailed information of several stages of
the hinge formation (A,B,IO,LS,CP,C,D,E) has also been illustrated.. Keywords: Soft Storey, Stiffness, Storey Drift, Storey Displacement, Earthquake, RC Frames
Seismic Vulnerability of RC Building With and Without Soft Storey Effect Usi...IJMER
A soft storey is one which has less resistance to earthquake forces than the other storeys;
Buildings containing soft stories are extremely vulnerable to earthquake collapses, since one floor is
flexible compared to others. Vulnerability of buildings is important in causing risk to life hence special
consideration is necessary for such soft storey RC buildings. In the present study, analytical
investigation of a RC building by considering the effect of soft storey situated in seismic Zone-V of
India, in accordance with IS 1893-2002 (part-1), is taken as an example and the various analytical
approaches (linear static and nonlinear static analysis) are performed on the building to identify the
seismic demand and also pushover analysis is performed to determine the performance levels, and
Capacity spectrum of the considered, also Storey Shear is compared for 3 models by using Finite
Element Software Package ETAB’s 9.7.4 version.
1) The document presents the results of a linear and non-linear analysis of reinforced concrete frames with members of varying inertia (non-prismatic beams) for buildings ranging from G+2 to G+10 storeys.
2) Both bare frames and frames with infill walls were analyzed considering different beam cross-sections - prismatic, linear haunch, parabolic haunch, and stepped haunch.
3) The linear analysis was performed using ETABS and considered parameters like fundamental time period, base shear, and top storey displacement. The non-linear analysis used pushover analysis in SAP2000 to determine effective time period, effective stiffness, and hinge formation patterns.
Performance based analysis of rc building consisting shear wall and varying i...Yousuf Dinar
Abstract:
Metropolitan cities are under severe threat because of inappropriate design and construction of structures. Faulty building designed without considering seismic consideration could be vulnerable to damage even under low levels of ground shaking from distant earthquake. So, structural engineers often are more concerned about the constructing Shear wall without knowing its performance with respect to infill percentage which may lead it to an over design state without knowing the demand. Nonlinear inelastic pushover analysis provides a better view about the behavior of the structures during seismic events. This study investigates as well as compares the performances of bare, different infill percentage level and two types of Shear wall consisting building structures and suggests from which level of performance shear wall should be preferred over the infill structure. To perform the finite element simulation ETABS 9.7.2 is used to get the output using pushover analysis. For different loading conditions, the performances of structures are evaluated with the help of base shear, deflection, storey drift, storey drift ratio and stages of number of hinges form and represented with discussion.
Descriptive study of pushover analysis in rcc structures of rigid jointYousuf Dinar
ABSTRACT: Structures in mega cities, are under serious threat because of faulty and unskilled design and construction of structures. Sometimes structure designers are more concerned in constructing different load resistant members without knowing its necessity and its performance in the structure. Different configuration of construction may also lead to significant variation in capacity of the same structure. Nonlinear static pushover analysis provides a better view on the performance of the structures during seismic events. This comprehensive research evaluates as well as compares the performances of bare, different infill percentage level, different configuration of soft storey and Shear wall consisting building structures with each other and later depending upon the findings, suggests from which level of performance shear wall should be preferred over the infill structure and will eventually help engineers to decide where generally the soft storey could be constructed in the structures. Above all a better of effects of pushover analysis could be summarized from the findings. Masonry walls are represented by equivalent strut according to pushover concerned codes. For different loading conditions, the performances of structures are evaluated with the help of performance point, base shear, top displacement, storey drift and stages of number of hinges form.
The document provides an overview of a course on performance-based seismic design of structures. It discusses key topics that will be covered in the course including an introduction to performance-based seismic design, fundamental considerations, analysis methods like nonlinear static and dynamic analysis, modeling approaches for structural members, and guidelines from organizations like ASCE, FEMA, and JRA. It also provides background on the development of performance-based seismic design and its advantages over traditional force-based seismic design methods.
Progressive Collapse Analysis of RC Buildings with consideration of Effect of...ijsrd.com
To study the effect of failure of load carrying elements i.e. columns on the entire structure; 15 storey moment resistant RC buildings is considered. The buildings are modeled and analyzed for progressive collapse using the structural analysis and design software SAP2000. Normally it has been considered only the failure of primary load carrying members like columns, beams, struts, foundations etc. to understand the progressive collapse scenario. This paper involves the effect of slabs in progressive collapse with the failure of column.
Pushover Analysis of Balance Cantilever BridgeIRJET Journal
This document discusses pushover analysis that was performed on a 3D model of a balanced cantilever bridge in CSI Bridge software. Pushover analysis applies monotonically increasing lateral loads to identify the bridge's performance under seismic loads. The analysis results, such as generation of plastic hinges, base shear, and displacement curves, are studied. The bridge is also analyzed for tracked and vehicle loads as per Indian standards. The process of modeling the bridge and defining analysis parameters in CSI Bridge software is described.
Non-Linear Static Analysis of Reinforced Concrete BridgeIRJET Journal
This document discusses performing non-linear static (pushover) analysis on reinforced concrete bridges to evaluate their seismic performance. Two series of bridge models are analyzed: one with a fixed span and varying pier heights, and one with fixed pier heights and varying spans. The bridges are modeled in software and pushover analysis is conducted according to methods in FEMA 356, ATC40, and FEMA 440. The results show that the bridges designed according to Indian codes may not meet performance goals in non-linear pushover analysis. Accurately modeling material properties and structural elements is important for the non-linear analysis.
IRJET- Seismic Behavior of RC Flat Slab with and without Shear Wall Techn...IRJET Journal
This document analyzes the seismic behavior of reinforced concrete flat slab buildings with and without shear walls using response spectrum analysis and equivalent static force method. Five models of a 7-story building are considered: a bare frame with flat slab, exterior shear wall, L-shaped shear wall, rectangular shear wall, and lift core shear wall. Results for base shear, story drift, displacement, and acceleration are obtained and compared using ETABS software for zone 5 seismicity. The analysis finds that shear walls improve seismic performance by resisting lateral loads and limiting structural deformation and damage.
This document analyzes the seismic performance of irregular L-shaped reinforced concrete buildings of varying heights (4, 8, and 20 stories) located in seismic Zone III. Six models of each building are considered: a bare frame, frame with infill walls modeled as membranes, and frame with infill walls modeled as equivalent diagonal struts. Nonlinear time history and pushover analyses are performed using ETABS. The results show that modeling infill walls improves seismic performance by reducing top story displacement and increasing base shear capacity, with the equivalent strut model performing better than the membrane model. The influence of infill walls decreases with increasing building height.
Non-Linear Static (Pushover) Analysis of Irregular Building SystemsIRJET Journal
This document discusses the non-linear static (pushover) analysis of irregular building systems. It presents 6 building models of 13-story reinforced concrete buildings with different configurations of masonry infill walls and concrete shear walls to study their seismic performance. Non-linear static pushover analysis is performed using ETABS software to obtain the capacity curves and evaluate the performance of each model under seismic loading. The results show that the inclusion of masonry infill walls and concrete shear walls affects the seismic response of the irregular buildings, and that some configurations perform better than others.
1. This document discusses performing a pushover analysis on a flat slab building using SAP2000 software to evaluate its seismic performance.
2. A pushover analysis applies increasing lateral loads to identify weak zones and determine the building's strength and deformation capacities.
3. The analysis revealed that retrofitting weak columns with jacketing and adding beams could significantly improve the building's lateral strength and stiffness to withstand seismic forces.
Study of seismic analysis and design of multi storey symmetrical and asymmetr...IRJET Journal
This document summarizes a study on the seismic analysis and design of symmetric and asymmetric multi-story buildings. Finite element software was used to model and analyze G+15 story reinforced concrete buildings with regular and irregular configurations subjected to response spectrum analysis and time history analysis. Results found that irregular buildings experienced higher displacements, drifts, and forces compared to regular structures. Specifically, structures with mass or stiffness irregularities performed poorer under seismic loads. A comparison of response spectrum and time history analyses found that time history analysis more accurately predicted structural response. The study concluded that structural configuration significantly impacts seismic response and irregular structures are more vulnerable during earthquakes.
Non linear static pushover analysis of irregular space frame structure with a...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Pushover is a static-nonlinear analysis method where a structure is subjected to gravity loading and a monotonic displacement-controlled lateral load pattern which continuously increases through elastic and inelastic behavior until an ultimate condition is reached. Lateral load may represent the range of base shear induced by earthquake loading, and its configuration may be proportional to the distribution of mass along building height, mode shapes, or another practical means.
The static pushover analysis is becoming a popular tool for seismic performance evaluation of existing and new structures. The expectation is that the pushover analysis will provide adequate information on seismic demands imposed by the design ground motion on the structural system and its components. The purpose of the paper is to summarize the basic concepts on which the pushover analysis can be based, assess the accuracy of pushover predictions, identify conditions under which the pushover will provide adequate information and, perhaps more importantly, identify cases in which the pushover predictions will be inadequate or even misleading.
Importance of Non Structural Elements during Earthquakemehul doshi
This document discusses the importance of designing non-structural elements (NSEs) for earthquake resistance. NSEs such as furniture, equipment, and components attached to buildings can cause damage or injuries if not properly secured during seismic activity. The document reviews literature showing NSEs have performed poorly in past earthquakes. It discusses challenges in designing NSEs, which can be sensitive to forces or displacements during shaking. Proper design of connections and allowing for relative movement between NSEs and structural elements is needed. The document observes more emphasis should be placed on NSE design given their costs and role in post-earthquake usability and safety.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
IRJET- Comparative Study on Conventional Slab and Flat Slabs RCC Structure us...IRJET Journal
This document discusses a comparative study on the seismic performance of conventional slab reinforced concrete (RCC) structures and flat slab RCC structures using pushover analysis. It aims to compare the structures' behavior under parameters like base shear, story displacement, and story drift. The study finds that under equivalent pushover analysis, the conventional slab RCC structure performs better with lower base shear, story drift, and story displacement values compared to flat slab and flat plate RCC structures. Overall, the conventional slab structure is considered more seismically efficient. The document provides background on pushover analysis methodology and outlines the objectives to explore and compare the seismic behavior of different slab RCC structures through nonlinear static analysis.
Effect of soft storeys in earthquake resistant analysis of rc framed structureseSAT Journals
storey in which the stiffness is less than 70% of the storey above or less
than 80% of the combined stiffnesses of the three storeys above. It is the general practice in the multistoreyed buildings to
accommodate parking facilities for the vehicles of the occupants of the building. As we know that the soft storey in a building
structure causes stiffness irregularity in a structure, due to this the structure undergoes unequal storey drifts, formation of the
plastic hinges and then finally resulting into the collapse of the structure.This research work purely interacts with the effect of the
soft storeys in the analysis of RC framed structures as entitled above, and in this work the soft storeys positions has been provided
at different levels as shown in the analytical modelling. All the models are analyzed by using the ETABS software. The seismic
analysis performed consists of the Equivalent static analysis (ESA), response spectrum analysis (RSA), and the push over analysis
(PA). The seismic base shear forces, storey drifts, and the displacements has been compared with the three analysis methods as
listed above. With the aid of the push over analysis the values of the ductility and the response reduction factor have been
obtained. Apart from these, the performance point parameters such as spectral acceleration(Sa) , spectral displacement (Sd),
Base shear(V) and the roof displacement(D) has been also illustrated in this work and a detailed information of several stages of
the hinge formation (A,B,IO,LS,CP,C,D,E) has also been illustrated.. Keywords: Soft Storey, Stiffness, Storey Drift, Storey Displacement, Earthquake, RC Frames
Seismic Vulnerability of RC Building With and Without Soft Storey Effect Usi...IJMER
A soft storey is one which has less resistance to earthquake forces than the other storeys;
Buildings containing soft stories are extremely vulnerable to earthquake collapses, since one floor is
flexible compared to others. Vulnerability of buildings is important in causing risk to life hence special
consideration is necessary for such soft storey RC buildings. In the present study, analytical
investigation of a RC building by considering the effect of soft storey situated in seismic Zone-V of
India, in accordance with IS 1893-2002 (part-1), is taken as an example and the various analytical
approaches (linear static and nonlinear static analysis) are performed on the building to identify the
seismic demand and also pushover analysis is performed to determine the performance levels, and
Capacity spectrum of the considered, also Storey Shear is compared for 3 models by using Finite
Element Software Package ETAB’s 9.7.4 version.
1) The document presents the results of a linear and non-linear analysis of reinforced concrete frames with members of varying inertia (non-prismatic beams) for buildings ranging from G+2 to G+10 storeys.
2) Both bare frames and frames with infill walls were analyzed considering different beam cross-sections - prismatic, linear haunch, parabolic haunch, and stepped haunch.
3) The linear analysis was performed using ETABS and considered parameters like fundamental time period, base shear, and top storey displacement. The non-linear analysis used pushover analysis in SAP2000 to determine effective time period, effective stiffness, and hinge formation patterns.
Performance based analysis of rc building consisting shear wall and varying i...Yousuf Dinar
Abstract:
Metropolitan cities are under severe threat because of inappropriate design and construction of structures. Faulty building designed without considering seismic consideration could be vulnerable to damage even under low levels of ground shaking from distant earthquake. So, structural engineers often are more concerned about the constructing Shear wall without knowing its performance with respect to infill percentage which may lead it to an over design state without knowing the demand. Nonlinear inelastic pushover analysis provides a better view about the behavior of the structures during seismic events. This study investigates as well as compares the performances of bare, different infill percentage level and two types of Shear wall consisting building structures and suggests from which level of performance shear wall should be preferred over the infill structure. To perform the finite element simulation ETABS 9.7.2 is used to get the output using pushover analysis. For different loading conditions, the performances of structures are evaluated with the help of base shear, deflection, storey drift, storey drift ratio and stages of number of hinges form and represented with discussion.
Descriptive study of pushover analysis in rcc structures of rigid jointYousuf Dinar
ABSTRACT: Structures in mega cities, are under serious threat because of faulty and unskilled design and construction of structures. Sometimes structure designers are more concerned in constructing different load resistant members without knowing its necessity and its performance in the structure. Different configuration of construction may also lead to significant variation in capacity of the same structure. Nonlinear static pushover analysis provides a better view on the performance of the structures during seismic events. This comprehensive research evaluates as well as compares the performances of bare, different infill percentage level, different configuration of soft storey and Shear wall consisting building structures with each other and later depending upon the findings, suggests from which level of performance shear wall should be preferred over the infill structure and will eventually help engineers to decide where generally the soft storey could be constructed in the structures. Above all a better of effects of pushover analysis could be summarized from the findings. Masonry walls are represented by equivalent strut according to pushover concerned codes. For different loading conditions, the performances of structures are evaluated with the help of performance point, base shear, top displacement, storey drift and stages of number of hinges form.
The document provides an overview of a course on performance-based seismic design of structures. It discusses key topics that will be covered in the course including an introduction to performance-based seismic design, fundamental considerations, analysis methods like nonlinear static and dynamic analysis, modeling approaches for structural members, and guidelines from organizations like ASCE, FEMA, and JRA. It also provides background on the development of performance-based seismic design and its advantages over traditional force-based seismic design methods.
Progressive Collapse Analysis of RC Buildings with consideration of Effect of...ijsrd.com
To study the effect of failure of load carrying elements i.e. columns on the entire structure; 15 storey moment resistant RC buildings is considered. The buildings are modeled and analyzed for progressive collapse using the structural analysis and design software SAP2000. Normally it has been considered only the failure of primary load carrying members like columns, beams, struts, foundations etc. to understand the progressive collapse scenario. This paper involves the effect of slabs in progressive collapse with the failure of column.
Pushover Analysis of Balance Cantilever BridgeIRJET Journal
This document discusses pushover analysis that was performed on a 3D model of a balanced cantilever bridge in CSI Bridge software. Pushover analysis applies monotonically increasing lateral loads to identify the bridge's performance under seismic loads. The analysis results, such as generation of plastic hinges, base shear, and displacement curves, are studied. The bridge is also analyzed for tracked and vehicle loads as per Indian standards. The process of modeling the bridge and defining analysis parameters in CSI Bridge software is described.
Non-Linear Static Analysis of Reinforced Concrete BridgeIRJET Journal
This document discusses performing non-linear static (pushover) analysis on reinforced concrete bridges to evaluate their seismic performance. Two series of bridge models are analyzed: one with a fixed span and varying pier heights, and one with fixed pier heights and varying spans. The bridges are modeled in software and pushover analysis is conducted according to methods in FEMA 356, ATC40, and FEMA 440. The results show that the bridges designed according to Indian codes may not meet performance goals in non-linear pushover analysis. Accurately modeling material properties and structural elements is important for the non-linear analysis.
IRJET- Seismic Behavior of RC Flat Slab with and without Shear Wall Techn...IRJET Journal
This document analyzes the seismic behavior of reinforced concrete flat slab buildings with and without shear walls using response spectrum analysis and equivalent static force method. Five models of a 7-story building are considered: a bare frame with flat slab, exterior shear wall, L-shaped shear wall, rectangular shear wall, and lift core shear wall. Results for base shear, story drift, displacement, and acceleration are obtained and compared using ETABS software for zone 5 seismicity. The analysis finds that shear walls improve seismic performance by resisting lateral loads and limiting structural deformation and damage.
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1. This document discusses performing a pushover analysis on a flat slab building using SAP2000 software to evaluate its seismic performance.
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Study of seismic analysis and design of multi storey symmetrical and asymmetr...IRJET Journal
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Non linear static pushover analysis of irregular space frame structure with a...eSAT Publishing House
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Pushover is a static-nonlinear analysis method where a structure is subjected to gravity loading and a monotonic displacement-controlled lateral load pattern which continuously increases through elastic and inelastic behavior until an ultimate condition is reached. Lateral load may represent the range of base shear induced by earthquake loading, and its configuration may be proportional to the distribution of mass along building height, mode shapes, or another practical means.
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2. 2 Presented by Rahul Leslie
The Pushover Analysis – from basics
Introduction
• Performance Based Design --- an emerging field
– To provide engineers with a capability to design buildings that have
predictable and reliable performance in earthquakes
– It employs concept of ‘performance objectives’, which is the
specification of an acceptable level of damage on experiencing a
earthquake of a given severity.
(FEMA 349)
• Seismic design for the future
– Presently a linear elastic analysis alone is sufficient for both its elastic
and ductile design
– In course of time, for large critical structures, a specially dedicated non-
linear procedure will have to be done, which finally influences the
seismic design as a whole.
3. Introduction
• Linear approach (IS:1893-2002)
is based on the Response
Reduction factor R.
–
–
–
– For example, R = 5, means that
1/5th of the seismic force is
taken by the Limit State capacity
of the structure.
Further deflection is taken by the
ductile capacity of the structure.
Reinforced Concrete (RC)
members are detailed (as per
IS:13920) to confirm its ductile
capacity.
We never analyse for the ductile
part, but only follow the
reinforcement detailing
guidelines for the same.
3 Presented by Rahul Leslie
The Pushover Analysis – from basics
4. Introduction
• The drawback is that the response
beyond the limit state is neither a
simple extrapolation, …
• … nor a perfectly ductile behaviour
with pre-determinable deformation
capacity, due to various reasons:
–
–
– Change in stiffness of members due
to cracking and yielding,
P-delta effects,
Change in the final seismic force
estimated (due to Change in
•
•
time period ‘T’ and
effective damping ratio ‘ζ
’ (also
represented by ‘β’)
– etc.
4 Presented by Rahul Leslie
The Pushover Analysis – from basics
5. 5 Presented by Rahul Leslie
The Pushover Analysis – from basics
Introduction
• Although elastic analysis gives a good indication of elastic capacity
of structures and shows where yielding will first occur,
– It cannot predict the redistribution of forces during the progressive
yielding that follows and predict its failure mechanisms.
• A non-linear static analysis can predict these more accurately.
– It can help identify members likely to reach critical states during an
earthquake for which attention should be given during design and
detailing.
6. 6 Presented by Rahul Leslie
The Pushover Analysis – from basics
Introduction
The Pushover Analysis (PA):
• PA is a non-linear analysis procedure to estimate the strength
capacity of a structure beyond its Limit State up to its ultimate
strength.
• It can help demonstrate how progressive failure in buildings most
probably occurs, and identify the mode of final failure.
• The method also predicts potential weak areas in the structure, by
keeping track of the sequence of damages of each and every
member in the structure.
7. 7 Presented by Rahul Leslie
The Pushover Analysis – from basics
PA can be useful under two situations:
➢ When an existing structure has deficiencies in seismic resisting
capacity,
▪
▪
due to either omission of seismic design when built, or
the structure becoming seismically inadequate due
upgradation of the seismic codes,
to a later
is to be retrofitted to meet the (present) seismic demands,
PA can show where the retrofitting is required and how much.
➢ For a building in its design phase, PA results help scrutinise and
fine tune the seismic design based on SA.
Introduction
8. 8 Presented by Rahul Leslie
The Pushover Analysis – from basics
• For a new building, PA is meant to be a second stage analysis (The
first stage being a conventional Seismic analysis - SA).
• This is because the details of reinforcement provided are required to
calculate exact hinge properties (to be covered later)
• But one has to design the structure based on SA in order to obtain
the reinforcement details.
• This means that PA is meant to be a second stage analysis (The first
stage being a conventional SA).
• Thus the emerging methodology to an accurate seismic design is:
1. First a conventional linear seismic analysis based on which a primary
structural design is done;
2. Insertion of hinges determined based on the design/detail and then
3. A pushover analysis is done, followed by
4. Modification of the design and detailing, wherever necessary, based
on the latter analysis.
5. The above steps may have to be iterated, if required.
Introduction
9. Features of a Typical Pushover Approach
• The model, which is a Multi-degree of freedom (MDoF) model, is
used for the analysis
There are certain features common to all PA approaches:
9 Presented by Rahul Leslie
The Pushover Analysis – from basics
–
–
–
1. An analysis model of the building, is generated using a common
analysis-design software package (having facility for PA), like
STAAD.Pro,
SAP2000, ETABS,
MIDAS/Gen, etc.
10. 10 Presented by Rahul Leslie
The Pushover Analysis – from basics
Non-linear Building model & Non-linear Hinges
Pushover analysis uses a non-linear computer model
for the analysis:
– This is done by incorporated in the form of non-linear hinges
inserted into an otherwise linear elastic model which one
generates using a common analysis-design software package
(STAAD.Pro, SAP2000, ETABS, MIDAS/Gen, etc.)
– Hinges are points on a structure where one expects cracking
and yielding to occur in relatively higher intensity so that they
show higher flexural/shear displacement, under a cyclic loading
11. - These are locations where one expects to see cross
diagonal cracks in an actual building structure after a
seismic mayhem
– they would be at either ends of beams and columns, the ‘cross’
being at a small distance from the joint
– this is where one inserts hinges in the corresponding computer
model.
Non-linear Building model & Non-linear Hinges
11 Presented by Rahul Leslie
The Pushover Analysis – from basics
12. 12 Presented by Rahul Leslie
The Pushover Analysis – from basics
• Basically a hinge represents localised force-displacement relation of
a member through its elastic and inelastic phases under seismic
loads.
• A flexural hinge represents the moment-rotation relation of a beam.
• Hinges are of various types – namely,
–
–
–
(1) flexural hinges,
(2) shear hinges
(3) axial hinges.
Non-linear Building model & Non-linear Hinges
13. • The flexural and shear hinges
are inserted into the ends of
beams and columns.
• Since the presence of masonry
infills have significant influence
on the seismic behaviour of
the structure, modelling them
using equivalent diagonal
struts (of ‘truss’ elements) is
common in PA
• The axial hinges are inserted
at either ends of the diagonal
struts
Non-linear Building model & Non-linear Hinges
13 Presented by Rahul Leslie
The Pushover Analysis – from basics
14. Typical Moment Hinge property:
• AB represents the linear range
from unloaded state (A) to its
effective yield (B),
• Followed by an inelastic but
linear response of reduced
(ductile) stiffness from B to C.
• CD shows a sudden reduction
in load resistance, followed by
a reduced resistance from D to
E, and
• finally a total loss of resistance
from E to F.
Flexural Hinge
14 Presented by Rahul Leslie
The Pushover Analysis – from basics
Non-linear Building model & Non-linear Hinges
15. • These hinges have non-linear
states defined within its ductile
range as
–
–
–
‘Immediate Occupancy’ (IO),
‘Life Safety’ (LS) and
‘Collapse Prevention’ (CP)
• This is usually done by dividing
B-C into four parts and
denoting IO, LS and CP, which
are states of each individual
hinges
Flexural Hinge
Non-linear Building model & Non-linear Hinges
15 Presented by Rahul Leslie
The Pushover Analysis – from basics
16. There are certain features common to all PA approaches:
2. The model is pushed monotonically with an invariable distribution of lateral load with some predefined
distribution pattern such as:
– Proportional to 1st mode (or SRSS combination of modes)
– Inverted triangle / Uniform distribution
– Power distribution (for example, parabolic)
k
j j
i
i i
n
b
i
Q V
W h
W hk
Features of a Typical Pushover Approach
16 Presented by Rahul Leslie
The Pushover Analysis – from basics
17. There are certain features common to all PA approaches:
2. (Continuation …)
• Unlike conventional SA, in Pushover analysis, analysis for Gravity
loads is done first, continued by an analysis for Lateral loads.
• Since PA is done to simulate the behaviour under actual loads, the
Gravity loads applied are not factored, but in accordance with
Cl.7.3.3 and Table 8 of IS:1893-2002 :
[DL + 0.25 LL≤3kN/sq.m+ 0.5 LL>3kN/sq.m]
Features of a Typical Pushover Approach
17 Presented by Rahul Leslie
The Pushover Analysis – from basics
18. 3. A pushover curve is obtained, which is a Base shear (Vb) vs. Roof
top displacement (Δrt) curve
– Base shear is sum of all horizontal support reactions in that
direction
– Roof top displacement is the displacement at the centre of
mass of the general roof
Features of a Typical Pushover Approach
18 Presented by Rahul Leslie
The Pushover Analysis – from basics
19. 4. A single-degree of freedom (SDoF) model, corresponding to the MDoF model, and
the rules to convert the parameters of the MDoF model (Vb & Δrt) to those of the
SDoF model (Sa & Sd) are defined
Features of a Typical Pushover Approach
19 Presented by Rahul Leslie
The Pushover Analysis – from basics
20. 4. (Continuation…) A single-degree of freedom (SDoF) model,
corresponding to the MDoF model, and the rules to convert the
parameters of the MDoF model (Vb & Δrt) to those of the SDoF model
(Sa & Sd) are defined
– In ATC-40 and FEMA440, the conversion is
– In EC 8 (where Sa and Sd are denoted by F* and d* respectively)
and
V /W
Sa b
M
(where M ), and
k1
Pk1 k 1,@rt
rt
Sd
Pk1
Sa
Vb
Pk1
20 Presented by Rahul Leslie
The Pushover Analysis – from basics
Sd
rt
Features of a Typical Pushover Approach
21. 5. The Sa-Sd curve has to be converted to an equivalent bi-linear
curve (equal energy) by a suitable method
– Different codes follow different methods
– ATC-40 and FEMA440 follows the
method of keeping the 1stline as initial
tangent stiffness and adjusts the 2nd
line (to the point under consideration)
such that to get the ‘equal area’.
ATC-40 and FEMA440
Features of a Typical Pushover Approach
21 Presented by Rahul Leslie
The Pushover Analysis – from basics
22. 5. The Sa-Sd curve has to be converted to an equivalent bi-linear
curve (equal energy) by a suitable method
– Different codes follow different methods
– EC8 (EuroCode 8) follows the method of
keeping the 2nd line (to the point under
consideration) as ‘perfectly plastic’, ie.,
horizontal and adjusts the 1st line such
that to get the ‘equal area’.
EC 8
Features of a Typical Pushover Approach
22 Presented by Rahul Leslie
The Pushover Analysis – from basics
23. –
5. The Sa-Sd curve has to be converted to an equivalent bi-linear
curve (equal energy) by a suitable method
Different codes follow different methods
ATC-40 and FEMA440 EC8
Features of a Typical Pushover Approach
23 Presented by Rahul Leslie
The Pushover Analysis – from basics
24. 24
PA procedures can generally be classified to two:
-
-
-
1. DCM (Displacement Coeff. Method): These procedures
estimates a Target displacement prior to the analysis, to which
the model has to be pushed, and on analysis, checked for the
intended (good) performance at that displacement. The method
is nevertheless, iterative. Ref:-
FEMA356,
FEMA440 (Ch.5),
EC 8
2. CSM (Capacity Spectrum Method): The analysis is done, and
each pt. on the pushover curve (known as Capacity curve) is
consecutively checked to see whether the Sa-Sd at that pt.
meets (or intersects) the Response Spectrum curve (known as
Demand curve), reduced by a factor. (continued…)
Different Pushover Approaches
The Pushover Analysis – from basics Presented by Rahul Leslie
25. 25
Presented by Rahul Leslie
PA procedures can generally be classified to two:
-
-
-
2. CSM : … For each point on the Capacity curve, the Demand
curve to be checked with, for intersection, is a Response
Spectrum curve reduced by a reduction factor calculated
corresponding to that point under consideration on the Capacity
curve. When the curves intersects (or meet), that meeting point
is known as the Performance Pt. Ref:-
ATC-40,
FEMA440 (Ch.6)
EC8 (Optional method)
Different Pushover Approaches
The Pushover Analysis – from basics
26. The steps for the CSM method are:
1. First, the Response Spectrum (RS) curve has to be modified: from its ordinates of Sa vs. Time period ‘T’, to its
‘Acceleration Displacement Response Spectrum’ (ADRS) form, which is an Sa vs. Sd curve.
• This to facilitate the super-imposing the pushover curve over the RS (which is in its ADRS form)
Steps for CSM method of Pushover Analysis
RS
The Pushover Analysis – from basics
ADRS
26 Presented by Rahul Leslie
27. The steps for the CSM method are:
1. First, the Response Spectrum (RS) curve has to be modified:
from its ordinates of Sa vs. Time period, to its ‘Acceleration
Displacement Response Spectrum’ (ADRS) form, which is an
Sa vs. Sd curve.
• This is done by using the relation
T 2
RS
The Pushover Analysis – from basics
ADRS
27 Presented by Rahul Leslie
4 2
Sd Sa
Steps for CSM method of Pushover Analysis
28. 2. Super-impose the converted Pushover curve on the ADRS curve:
Steps for CSM method of Pushover Analysis
28 Presented by Rahul Leslie
The Pushover Analysis – from basics
29. 3. With the Capacity curve (Pushover curve) superimposed on the Demand
curve (ADRS), each point on the former is consecutively checked to :
i. Get the yield point ordinates (Say & Sdy)
ii. Calculate the ductility μand the 2nd tangent stiffness coeff. α
ATC-40, FEMA440 EC8
Steps for CSM method of Pushover Analysis
29 Presented by Rahul Leslie
The Pushover Analysis – from basics
30. iii.
▪
▪
Determine the reduced ADRS for the above parameters corresponding to that pt. on the Capacity curve
as:
ATC-40/FEMA440 : Calculate damping βfrom ductility μand 2nd tangent stiffness coefficient α
.Reduce ADRS
corresponding to β
EC 8 : Reduce ADRS corresponding to ductility μ
ATC-40, FEMA440
30 Presented by Rahul Leslie
The Pushover Analysis – from basics
EC8
Steps for CSM method of Pushover Analysis
31. • For example, in ATC-40, for the reduction of the Demand (ADRS)
curve, the ‘effective’ damping ratio β is determined from the
formula :
Steps for CSM method of Pushover Analysis
dy
dp
1
0.05
2 11
eff
Kinit
K2nd
init
d
K
y p y
K
d d
ay
ap ay
2nd
31 Presented by Rahul Leslie
The Pushover Analysis – from basics
32. 32
• …where the Damping Modification Factor κ
is determined from
the building type
Table : Structural behaviour types Table : Values for Damping
Modification Factor κ
Shaking
Duration
Essentially
New
Building
Type A
Type B
Average
Existing
Building
Type B
Type C
Poor
Existing
Building
Type C
Type C
Short
Long
Structure β
behaviou
r type
eq(%)
κ
TypeA
≤16.25 1.0
1.13 0.51 / 20
>16.25
Type B
≤25 0.67
0.845 0.446 / 20
>25
Type C
Any
value
0.33
Presented by Rahul Leslie
Steps for CSM method of Pushover Analysis
2 11
0.05
1
eff
The Pushover Analysis – from basics
33.
2.12
e eff (%)
3.210.681Log
SRa
1.65
e eff (%)
2.31 0.41Log
SRv
Steps for CSM method of Pushover Analysis
• From the effective damping ratio β
,the factors for reducing the
ADRS curve are determined from the formula :
33 Presented by Rahul Leslie
The Pushover Analysis – from basics
34. 4. Include the reduced ADRS Demand curve in the super-imposed
graph:
Steps for CSM method of Pushover Analysis
34 Presented by Rahul Leslie
The Pushover Analysis – from basics
35. 35 Presented by Rahul Leslie
The Pushover Analysis – from basics
Step by step through each method
1. The conventional SA procedure is explained to highlight the
difference in approaches between SA & PA
2. Trace the progress of a PA from beginning to end,
• both demonstrates plots of Vb vs Δr
o
o
f
to
pand RS curve in its
– separate and uncombined form and
– also their transformed and super-positioned ADRS plot.
36. • In SA, the maximum DBE force acting on the structure is Z/2.(Sa/g),
(assuming I = 1) with Sa/g corresponding to the estimated time
period.
• Its envelop is the RS curve marked q
• The RS curve for the Limit State design is plotted in terms of Z/2R.
(Sa/g), and is marked as curve p.
Step by step through each method
-- SA Method
36 Presented by Rahul Leslie
The Pushover Analysis – from basics
37. • Fig. shows the Vb vs Δ
ro
o
fto
p displacement.
–The point P represents the Vb and Δro
o
fto
p for the design lateral load
(ie., of 1/R times full load)
– The point Q represents the same for the full load, had the building
been fully elastic
– Point Q' for a perfectly-elastic perfectly-ductile structure.
– The slope of the line OP represents
the stiffness of the structure in a
global sense. Since the analysis is
linear, the stiffness remains same
throughout the analysis, with Q
being an extension of OP.
Step by step through each method
-- SA Method
37 Presented by Rahul Leslie
The Pushover Analysis – from basics
38. Step by step through each method
-- SA Method
• The same is represented in Fig.(left) where, for the time period Tp of
the structure,
– the full load is represented by Q (Saq), and
– the design load by P (Sap).
38 Presented by Rahul Leslie
The Pushover Analysis – from basics
39. Step by step through each method
-- SA Method
• The ADRS representation of SA is as in Fig.(left).
– the full load is represented by Q (Saq),
– the design load by P (Sap).
39 Presented by Rahul Leslie
The Pushover Analysis – from basics
40. Step by step through each method
-- PA Method
Now we shall see how differently the PA approaches the same
scenario :-
• The segment OA in Fig.(left) is equivalent to OP in Fig.(right), with the
slope representing the global stiffness in its elastic range.
40 Presented by Rahul Leslie
The Pushover Analysis – from basics
41. Step by step through each method
-- PA Method
The RS curve : Segment OA has time period Ta, curve ‘a’ representing
the RS curve and Saa is the lateral load demand, in its elastic range.
41 Presented by Rahul Leslie
The Pushover Analysis – from basics
42. Step by step through each method
-- PA Method
• ADRS representation:
42 Presented by Rahul Leslie
The Pushover Analysis – from basics
43. Step by step through each method
-- PA Method
• As the analysis progresses, the lateral load is monotonically
increased beyond its elastic limit of A, and the first hinges are formed.
This decreases the overall stiffness of the structure. This is
represented by the segment AB.
• The decrease in slope of OB from that of OA shows the change in
secant stiffness.
43 Presented by Rahul Leslie
The Pushover Analysis – from basics
44. Step by step through each method
-- PA Method
• The first hinges are formed, decreasing the overall stiffness of the
structure, which in turn increases T and β
, represented by point B in
the plots.
44 Presented by Rahul Leslie
The Pushover Analysis – from basics
45. Step by step through each method
-- PA Method
• The change in the x-axis value of point B from that of point A shows
the shift of time period from Ta to Tb.
• The increase in βof the structure calls for a corresponding decrease
in the RS curve, reduced by a factor calculated from β
,which has thus
come down from curve a to b.
45 Presented by Rahul Leslie
The Pushover Analysis – from basics
46. Step by step through each method
-- PA Method
• ADRS representation: Note the angular shift from Ta to Tb .
• The increase in βof the structure calls for a corresponding decrease
in the RS curve, reduced by a factor calculated from β
,which has thus
come down from curve a to b.
46 Presented by Rahul Leslie
The Pushover Analysis – from basics
47. Step by step through each method
-- PA Method
• As the lateral load is further increased monotonically, more hinges are
formed and the existing hinges have further yielded in its non-linear
phase represented by point C
• This has further reduced the stiffness (the slope of OC),
47 Presented by Rahul Leslie
The Pushover Analysis – from basics
48. Step by step through each method
-- PA Method
• (Here are the two graphs overlapped – a possibility
48 Presented by Rahul Leslie
The Pushover Analysis – from basics
49. Step by step through each method
-- PA Method
• This has further reduced the stiffness, and increased T (from Tb to
Tc).
49 Presented by Rahul Leslie
The Pushover Analysis – from basics
50. Step by step through each method
-- PA Method
• More hinges are formed and the existing hinges have further yielded
in its non-linear phase, represented by point C
• Note the angular shift from Tb to Tc.
50 Presented by Rahul Leslie
The Pushover Analysis – from basics
51. Step by step through each method
-- PA Method
• Here the point C is where the capacity curve OABC extending
upwards meets the demand curve in, which was simultaneously
descending down to curve c.
• Thus C is the point where the total lateral force expected Sac is same
as the lateral force applied ~Vbc
• This point is known as the performance point.
51 Presented by Rahul Leslie
The Pushover Analysis – from basics
52. Step by step through each method
-- PA Method
• It is also defined as the point where the ‘locus of the performance
point’, the line connecting Saa, Sab and Sac, intersects the capacity
curve
52 Presented by Rahul Leslie
The Pushover Analysis – from basics
53. 53 Presented by Rahul Leslie
The Pushover Analysis – from basics
PA Method – Reviewing results
• Once the performance point is found, the overall performance of the
structure can be checked to see whether it matches the required
performance level, based on inter-storey drift limits specified in ATC-
40, which are
–
–
–
0.01h for IO,
0.02h for LS, and
0.33(Vb/W)∙h for CP, (h = height of the building).
• The performance level is based on the importance and function of the
building. For example, hospitals and emergency services buildings
are expected to meet a performance level of IO.
54. • The next step is to review the hinge formations at performance point.
One can see the individual stage of each hinge, at its location.
• Tables are obtained showing the number of hinges in each state, at
each stage, based on which one decides which all beams and
columns to be redesigned.
• The decision depends whether the most severely yielded hinges are
formed in beams or in columns, whether they are concentrated in a
particular storey denoting soft story, and so on.
PA Method – Reviewing results
OA AB BC
54 Presented by Rahul Leslie
The Pushover Analysis – from basics
55. Adaptation for the Indian Code
Adapting of Pushover Analysis (PA) for IS:1893-2002
• The PA has not been introduced in the Indian Standard code yet.
However the procedure described in ATC-40 can be adapted for the
seismic parameters of IS:1893-2002.
• The RS curve in ATC-40 is
described by parameters
55 Presented by Rahul Leslie
The Pushover Analysis – from basics
–
–
Ca and
Cv,
where the curve just as in IS:1893,
is having a flat portion of intensity
2.5 Ca and a downward sloping
portion described by Cv/T.
Resp. Spec (ATC-40)
56. • The seismic force in IS:1893-
2000 is represented by
(ZI/2R).(Sa/g), where Sa/g is
obtained from the RS curve,
which in our code is
represented by
–
–
2.5 in the flat portion &
the downward sloping
portion by
•
•
1/T for hard soil,
1.36/T for medium
soil and
1.67/T for soft soil.
•
Resp. Spec (IS:1893-2002)
56 Presented by Rahul Leslie
The Pushover Analysis – from basics
ZI Sa
2R g
Ah
Adaptation for the Indian Code
57. • On comparison it can be inferred that
– Ca = Z/2 and
– Cv = Z/2 for hard,
1.36∙Z/2 for medium and
1.67∙Z/2 for soft soil
• Here ‘I’ is not considered, since in PA, the criteria of importance of
the structure is taken care of by the performance levels (IO, LS & CP)
R is also not considered since PA is always done for the full lateral
load.
•
Resp. Spec (ATC-40) Resp. Spec (IS:1893-2002)
57 Presented by Rahul Leslie
The Pushover Analysis – from basics
Z Sa
2 g
ZI Sa
2R g
Ah
Adaptation for the Indian Code
58. 58 Presented by Rahul Leslie
The Pushover Analysis – from basics
• The ‘Limit State’ inter-storey drift limit specified in IS:1893-2002, being
0.004, when accounted for
–
–
R = 5 for ductile design and
I = 1.5 for important structures (IO performance level)
= 1.0 for ordinary structures (LS performance level)
gives 0.004∙R/I = 0.02 and 0.0133 for IO and LS respectively
• The drift limit can be compared with those specified in ATC-40 (0.01
and 0.02 for IO and LS respectively). The limit for IO in IS:1893-2002
is more relaxed than that in ATC-40.
• This 0.004∙R/I can be taken as the IS:1893-2002 limits for pushover
drift, where I takes the values corresponding to Important and
Ordinary structures for limits of IO and LS respectively.
Adaptation for the Indian Code
59. • Presented in this section are the results of a pushover analysis done
on a 10 storey RCC building of a shopping complex using the
structural package of SAP2000.
Example of a building analysis
59 Presented by Rahul Leslie
The Pushover Analysis – from basics
60. 60 Presented by Rahul Leslie
The Pushover Analysis – from basics
• In the model, beams and columns were
elements, into which the hinges were inserted.
modelled using frame
• Diaphragm action was assigned to the floor slabs to ensure integral
lateral action of beams in each floor.
• Although analysis was done in both transverse and longitudinal
directions, only the results of the former are discussed here.
• The lateral load was applied in pattern of that of the 1st mode shape
in the transverse direction of the building, with an intensity for DBE as
per IS:1893-2002, corresponding to zone-III in hard soil.
Example of a building analysis
61. • The ADRS plot shows the Sa and Sd at performance point as 0.085g
and 0.242m.
• The corresponding Vb and Δroof top are 1857.046 kN and 0.287m.
The value of effective T is 3.368s.
• The effective β at that level of the demand curve which met the
performance point is 26%.
Example of a building analysis
61 Presented by Rahul Leslie
The Pushover Analysis – from basics
62. 62 Presented by Rahul Leslie
The Pushover Analysis – from basics
Example of a building analysis
• Table shows the hinge state details at each step of the analysis.
Step
Δroof top
(m)
Vb
(kN)
A to
B
B to
IO
IO to
LS
LS to
CP
CP
to C
C to
D
D to
E > E
Total
Hinges
0 0 0 1752 0 0 0 0 0 0 0 1752
1 0.058318 1084.354 1748 4 0 0 0 0 0 0 1752
2 0.074442 1348.412 1670 82 0 0 0 0 0 0 1752
3 0.089645 1451.4 1594 158 0 0 0 0 0 0 1752
4 0.26199 1827.137 1448 168 136 0 0 0 0 0 1752
5 0.41105 2008.48 1384 144 136 88 0 0 0 0 1752
6 0.411066 1972.693 1384 146 136 86 0 0 0 0 1752
7 0.411082 1576.04 1376 148 136 39 0 0 53 0 1752
8 0.411098 1568.132 1376 148 136 37 0 0 55 0 1752
9 0.411114 1544.037 1375 149 136 31 0 0 61 0 1752
10 0.40107 1470.133 1375 149 136 31 0 0 61 0 1752
Hinge States
63. 63 Presented by Rahul Leslie
The Pushover Analysis – from basics
• For the performance point, taken as step 5 (which actually lies
between steps 4 and 5),
–
–
95% of hinges are within LS and IO performance levels
88% within IO performance level.
Hinge States
Example of a building analysis
Step
Δroof top
(m)
Vb
(kN)
A to
B
B to
IO
IO to
LS
LS to
CP
CP
to C
C to
D
D to
E > E
Total
Hinges
0 0 0 1752 0 0 0 0 0 0 0 1752
1 0.058318 1084.354 1748 4 0 0 0 0 0 0 1752
2 0.074442 1348.412 1670 82 0 0 0 0 0 0 1752
3 0.089645 1451.4 1594 158 0 0 0 0 0 0 1752
4 0.26199 1827.137 1448 168 136 0 0 0 0 0 1752
5 0.41105 2008.48 1384 144 136 88 0 0 0 0 1752
6 0.411066 1972.693 1384 146 136 86 0 0 0 0 1752
7 0.411082 1576.04 1376 148 136 39 0 0 53 0 1752
8 0.411098 1568.132 1376 148 136 37 0 0 55 0 1752
9 0.411114 1544.037 1375 149 136 31 0 0 61 0 1752
10 0.40107 1470.133 1375 149 136 31 0 0 61 0 1752
64. • Following figures shows the hinge states during various stages in
course of the analysis.
Example of a building analysis
Fig: Hinge states in the structure model at (a) step 0 & (b) step 3
Presented by Rahul Leslie
The Pushover Analysis – from basics
65. • Following figures shows the hinge states during various stages in
course of the analysis.
Example of a building analysis
Fig: Hinge states in the structure model at (c) step 5 & (d) step 8
Presented by Rahul Leslie
The Pushover Analysis – from basics
66. • Following figures shows the hinge states during various stages in
course of the analysis.
Example of a building analysis
Fig: Hinge states in the structure model at (e) step 10
Presented by Rahul Leslie
The Pushover Analysis – from basics
67. 67 Presented by Rahul Leslie
The Pushover Analysis – from basics
• Hinge properties
– Determining hinge properties (beams, columns, diagonal struts)
– Determining hinge properties for flat-slab and shear walls
• Seismic analysis design/detailing hinge property
calculation insertion of hinges Pushover Analysis
– Doing the above manually at a practically acceptable speed
– Non-availability of a semi-automatic method in standard Analysis
Packages (STAAD, ETABS, etc.) :
Facility to quickly define details of provided
reinforcement bars for beams & columns and have the package
to automatically insert appropriately calculated hinges not
available.
Issues
68. 68 Presented by Rahul Leslie
The Pushover Analysis – from basics
• Inclusion of building torsion (no standardized guidelines
available)
• Inclusion of higher modes in PA
– PA with vectors that represent the effects of multiple modes
(FEMA 356)
– Explicit consideration of Multiple Modes
• Modal Pushover Analysis (Chopra and Goel, (2001).
• Incremental Response Spectrum Analysis (Aydinoglu, 2003)
• Consecutive Modal Pushover (Poursha et al., 2009)
– Progressive changes in the load vector pattern applied to the
structure.
• Displacement Adaptive Pushover (Antoniou and Pinho, 2004)
• IS:1893-2002 is yet to include the method
Limitations
69. 69 Presented by Rahul Leslie
The Pushover Analysis – from basics
References:
• IS 1893 (Part 1)–2002, “Indian Standard Criteria for Earthquake Resistant
Design of Structures, Part 1: General Provision and Buildings”, Bureau of
Indian Standards, New Delhi.
• FEMA 356 (2000) “Prestandard and Commentary for the Seismic Rehabilitation
of Buildings”, Federal Emergency Management Agency, Washington, DC, USA.
• ATC-40 (1996) “Seismic Analysis and Retrofit of Concrete Buildings”, vol. I,
Applied Technology Council, Redwood City, CA, USA.
• FEMA-440 (2005) “Improvement of Nonlinear static seismic analysis
procedures”, Federal Emergency Management Agency, Washington, DC, U.S.A.
• prEN 1998-1 (2003) “Eurocode 8 Part 1: Design of structures for earthquake
resistance”, European Committee for Standardization, Brussels.
• Jisha S. V. (2008), Mini Project Report “Pushover Analysis”, Department of Civil
Engineering, T. K. M. College of Engineering, Kollam, Kerala.
70. 70 Presented by Rahul Leslie
The Pushover Analysis – from basics
A write up on this topic can be found at …
http://rahulleslie.blogspot.in/p/blog-page.html
… but covers only the ATC-40 method of pushover
analysis.
Note
71. An effort has
possible…
been made to present the topic as simple as
…presume, at least to some extend, the aim has been fulfilled.
Conclusion
Thank you
rahul.leslie@gmail.com
71