This document discusses how fracture mechanics can be used to better predict damage and failure of structures. It notes that current design codes are based on small-scale laboratory tests and do not account for size effects, which can lead to more brittle failures in larger structures. The document outlines how fracture mechanics considers factors like size effect, ductility, and minimum reinforcement that influence the strength and failure behavior of structures. It provides examples of how fracture mechanics has been applied to problems like evaluating shear strength in deep beams and investigating a failure of an oil platform structure. The document argues that fracture mechanics provides a more scientific basis for structural design compared to existing empirical code provisions.
MODELLING OF AN INFILL WALL FOR THE ANALYSIS OF A BUILDING FRAME SUBJECTED TO...IAEME Publication
In general the analysis of a building frame is carried out with a bare frame but the presence of masonry infill in a framed structure results in high stiffness and influence the distribution of lateral load and also the response of the framed buildings. It can be noted that there is a large variation of mechanical properties of bricks. Masonry, a combination of brick and mortar, behaves in a highly nonlinear manner. The infill panel needs to be modelled in the analysis of a structural frame subjected to lateral load to obtain its true behaviour. In order to model the masonry infill, its properties required. In order to determine the properties of brick masonry compression tests were conducted on masonry infill panels and prisms.
Behaviour of 3 d rc frames with masonry infill under earthquake loads an ana...eSAT Journals
Abstract Moderate and astringent earthquakes have struck different places in the world, causing rigorous damage to reinforced concrete
structures. The bond between the structural elements and masonry in-fills of the building is habitually effected by Earthquake. The
voids between horizontal and vertical resisting elements of the building frame is filled by Masonry in-fills. An infill wall enhances
considerably the strength and rigidity of the structure. It has apperceived that frames with in-fills have more vigor and rigidity
compared to the bare frames Hence this study is about the demeanor of 3D-RC frames with and without masonry in-fills utilizing
E-TABS. parameters were studied like displacement, lateral load distribution, stiffness and overturning moment of the frames and
it is concluded that, the in-fill walls are needed to be considered while designing phase of the structures.
Keywords: Earthquake load, 3D RC Frame, Masonry In-Fill
Numerical Analysis of Engineered Steel Fibers as Shear Reinforcement in RC BeamsP singh
Using suitable fibers and additives in concrete to enhance its performance is an important consideration in the concrete industry with regard to the structural aspects of concrete. The purpose of this project is to investigate numerically the effectiveness of the engineered steel fiber as shear reinforcement in RC beams. Here steel fibers completely replaces the shear reinforcement (stirrups & links). The dimension of beam taken was 1000*150*150 mm with aspect ratio 80. The beams were reinforced with 10 mm steel bars as secondary reinforcement and 12 mm bars as main reinforcement on the tension side. Numerical analysis using ANSYS R16.1 software package was carried out. The load-deflection curves for the beams with different dosage of fibers were drawn superimposing their numerical values. Initially, in all three cases the curve was linear elastic and about 80% of ultimate load they tend to be non-linear. It was observed that there was fair agreement between the results which indicates some favourable aspects concerning the use of steel fibres as shear reinforcement in concrete beams. It was investigated that the inclusion of steel fibres (Hook End Type) improves the shear strength of RC beams without stirrups by improving the matrix between concrete and steel fibers. Thus this project focuses in the design and analysis using the software ANSYS R16.1 for an alternative steel reinforcement with better or equivalent performance.
Effect of infill walls on the seismic performance of the multistoried buildingseSAT Journals
Abstract The most commonly used structural system in our country for almost all types of building are multi-storey reinforced concrete frames with masonry infills. Therefore it is essential to understand the seismic behaviour of these structures when subjected to lateral forces. Several research works has been done on the masonry infilled reinforced concrete frames in the past decades. Mortar is used as a binder in normal brick construction in order to create continuous structural form and to bind together the individual units in brickwork. In the present study, analysis has been carried out by considering the increase in height of building from five to ten storied by using finite element software ANSYS 14.5. The seismic analysis of multi-storeyed building frames with infill walls and without infill walls are conducted. 3D analysis will give more realistic values of deflection and stresses. Since this type of study is not feasible in terms of analysis time taken, 2D model was adopted for the present study. A three bay two dimensional building frame is considered with the number of stories varying from 5 storied to 10 storied. The loading applied is as per IS 1893 (Part I): 2002. Equivalent diagonal strut method is adopted for modelling infill walls. The results showed that there is considerable decrease in deflection when infills are used in RC frames. Key Words: Deflection , Equivalent diagonal strut method, lateral load, Solid brick infills, Storey drift
Analysis of rc framed structures with central and partial openings in masonry...eSAT Journals
Abstract In Reinforced concrete frames the masonry infill walls are a common practice in countries like India, where the region is prone to seismic activity. In general, the masonry infill walls are treated as nonstructural element in structural analysis and only the contribution of its mass for is considered and it’s structural parameters like strength and stiffness is generally ignored in practice, such an approach may lead to an unsafe design. Infill walls resist lateral loads but because of the openings in the infill wall the resistance may slightly reduce. The IS code provisions do not provide guidelines for the analysis and design of RC frames with infill wall and for different percentage of openings. In this study, an office or residential building outer side central opening or outer side partial openings are used and analysis is carried for Bare Frame model, infill walls without opening, infill walls with outer periphery central opening and infill wall with outer periphery partial opening models. In ETABS software G+14 RC framed building models has been prepared, Equivalent Static Lateral force method, Response spectrum method has been performed for analysis as per IS 1893 : 2002 including p-delta effects. Storey displacement, Storey shear, Storey drift, with soft storey considering the effects of infill wall with central and partial openings are the parameters considered in this study. For modeling, the Equivalent diagonal strut method has been used to find out the width of Strut using FEMA 273 .The results for bare frame, infill wall, and infill wall with central and partial openings are discussed and conclusions are made. Keywords: Equivalent diagonal strut, stiffness, Drift limitation
MODELLING OF AN INFILL WALL FOR THE ANALYSIS OF A BUILDING FRAME SUBJECTED TO...IAEME Publication
In general the analysis of a building frame is carried out with a bare frame but the presence of masonry infill in a framed structure results in high stiffness and influence the distribution of lateral load and also the response of the framed buildings. It can be noted that there is a large variation of mechanical properties of bricks. Masonry, a combination of brick and mortar, behaves in a highly nonlinear manner. The infill panel needs to be modelled in the analysis of a structural frame subjected to lateral load to obtain its true behaviour. In order to model the masonry infill, its properties required. In order to determine the properties of brick masonry compression tests were conducted on masonry infill panels and prisms.
Behaviour of 3 d rc frames with masonry infill under earthquake loads an ana...eSAT Journals
Abstract Moderate and astringent earthquakes have struck different places in the world, causing rigorous damage to reinforced concrete
structures. The bond between the structural elements and masonry in-fills of the building is habitually effected by Earthquake. The
voids between horizontal and vertical resisting elements of the building frame is filled by Masonry in-fills. An infill wall enhances
considerably the strength and rigidity of the structure. It has apperceived that frames with in-fills have more vigor and rigidity
compared to the bare frames Hence this study is about the demeanor of 3D-RC frames with and without masonry in-fills utilizing
E-TABS. parameters were studied like displacement, lateral load distribution, stiffness and overturning moment of the frames and
it is concluded that, the in-fill walls are needed to be considered while designing phase of the structures.
Keywords: Earthquake load, 3D RC Frame, Masonry In-Fill
Numerical Analysis of Engineered Steel Fibers as Shear Reinforcement in RC BeamsP singh
Using suitable fibers and additives in concrete to enhance its performance is an important consideration in the concrete industry with regard to the structural aspects of concrete. The purpose of this project is to investigate numerically the effectiveness of the engineered steel fiber as shear reinforcement in RC beams. Here steel fibers completely replaces the shear reinforcement (stirrups & links). The dimension of beam taken was 1000*150*150 mm with aspect ratio 80. The beams were reinforced with 10 mm steel bars as secondary reinforcement and 12 mm bars as main reinforcement on the tension side. Numerical analysis using ANSYS R16.1 software package was carried out. The load-deflection curves for the beams with different dosage of fibers were drawn superimposing their numerical values. Initially, in all three cases the curve was linear elastic and about 80% of ultimate load they tend to be non-linear. It was observed that there was fair agreement between the results which indicates some favourable aspects concerning the use of steel fibres as shear reinforcement in concrete beams. It was investigated that the inclusion of steel fibres (Hook End Type) improves the shear strength of RC beams without stirrups by improving the matrix between concrete and steel fibers. Thus this project focuses in the design and analysis using the software ANSYS R16.1 for an alternative steel reinforcement with better or equivalent performance.
Effect of infill walls on the seismic performance of the multistoried buildingseSAT Journals
Abstract The most commonly used structural system in our country for almost all types of building are multi-storey reinforced concrete frames with masonry infills. Therefore it is essential to understand the seismic behaviour of these structures when subjected to lateral forces. Several research works has been done on the masonry infilled reinforced concrete frames in the past decades. Mortar is used as a binder in normal brick construction in order to create continuous structural form and to bind together the individual units in brickwork. In the present study, analysis has been carried out by considering the increase in height of building from five to ten storied by using finite element software ANSYS 14.5. The seismic analysis of multi-storeyed building frames with infill walls and without infill walls are conducted. 3D analysis will give more realistic values of deflection and stresses. Since this type of study is not feasible in terms of analysis time taken, 2D model was adopted for the present study. A three bay two dimensional building frame is considered with the number of stories varying from 5 storied to 10 storied. The loading applied is as per IS 1893 (Part I): 2002. Equivalent diagonal strut method is adopted for modelling infill walls. The results showed that there is considerable decrease in deflection when infills are used in RC frames. Key Words: Deflection , Equivalent diagonal strut method, lateral load, Solid brick infills, Storey drift
Analysis of rc framed structures with central and partial openings in masonry...eSAT Journals
Abstract In Reinforced concrete frames the masonry infill walls are a common practice in countries like India, where the region is prone to seismic activity. In general, the masonry infill walls are treated as nonstructural element in structural analysis and only the contribution of its mass for is considered and it’s structural parameters like strength and stiffness is generally ignored in practice, such an approach may lead to an unsafe design. Infill walls resist lateral loads but because of the openings in the infill wall the resistance may slightly reduce. The IS code provisions do not provide guidelines for the analysis and design of RC frames with infill wall and for different percentage of openings. In this study, an office or residential building outer side central opening or outer side partial openings are used and analysis is carried for Bare Frame model, infill walls without opening, infill walls with outer periphery central opening and infill wall with outer periphery partial opening models. In ETABS software G+14 RC framed building models has been prepared, Equivalent Static Lateral force method, Response spectrum method has been performed for analysis as per IS 1893 : 2002 including p-delta effects. Storey displacement, Storey shear, Storey drift, with soft storey considering the effects of infill wall with central and partial openings are the parameters considered in this study. For modeling, the Equivalent diagonal strut method has been used to find out the width of Strut using FEMA 273 .The results for bare frame, infill wall, and infill wall with central and partial openings are discussed and conclusions are made. Keywords: Equivalent diagonal strut, stiffness, Drift limitation
EXPERIMENTAL MODELING OF IN FILLED RC FRAMES WITH OPENINGIAEME Publication
Reinforced concrete frames are usually infilled with masonry walls but, in most designs, both the shear strength capacity of these walls and the contribution of the infill panel openings on the shear strength of the infilled frame, especially in critical cases of seismic loading are generally ignored. This paper reports the results of an experimental study of the influence of central openings in the infill on the sway stiffness of reinforced concrete plane frames. A series of 1:4 scaled structural models with opening ratios from 0 to 50 percent in steps of 10 percent were designed, constructed and tested in the study to obtain the load - displacement profiles.
Seismic evaluation of rc frame with brick masonry infill wallseSAT Journals
Abstract
Infill panels are widely used as partition walls as well as external walls of the building to fill the gap between RC frames. Non-structural member may provide considerable stiffness to the building and hence may improve the performance of the RC building during ground motions. But In most of the cases, the ignorance of this property of masonry in designing of the RC frame may get an unsafe design. There are two methods are used to determine the effect of ground motion. The effect of ground motion on RC frame building has been carried out by considering with and without the stiffness of infill wall. A comparative study is carried out with RC building using Equivalent Lateral Force method and Response Spectrum method. The masonry infill has been modeled as an equivalent diagonal strut element using Hendry formula. Pushover analysis is carried out on bare frame and frame with infill wall. The model has been generated using STAAD Pro and results obtained from the analysis are compared in terms of strength and stiffness with bare frame.
Keywords: Seismic evaluation, Response Spectrum, masonry infill, diagonal strut.
Analysis of rc frame with and without masonry infill wall with different stif...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.
Flexural behaviour of interior r.c.beam column joint with and without slab un...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.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Static Analysis of Masonry Infilled R.C.Frame With &Without Opening Including...IOSR Journals
Masonry infill is considered as a non-structural element in all type of buildings where masonry use.
But, masonry infill walls are mainly used to increase initial stiffness and strength of reinforced concrete (RC)
frame buildings. This Open First storey is also termed as “Soft Storey”. The upper storeys have brick infilled
wall panels with various opening percentage in it. In many cities of India, it is very common to leave the first
storey of masonry infilled reinforcement concrete (RC) frame building open preliminary to generate parking
space or any other usage in the first storey. Such buildings are highly undesirable in seismically active areas. In
the present study, it is an attempt to access the performance of masonry infilled reinforced concrete (RC) frames
with soft storey of with and without opening. In this paper, symmetrical frame of college building (G+5) located
in seismic zone-III is considered by modelling of initial frame. According to FEMA-273, & ATC-40 which
contain the provisions of calculation of stiffness of infilled frames by modelling infill as“Equivalent Diagonal
Strut Method”. Therefore, the infill panels are modelled as equivalent diagonal strut method. The error
involved in modelling such buildings as neglecting the presence of infills in the upper storeys, is brought out
through the study of an example building with different analytical models. This linear static analysis is to be
carried out on the models such as Strut frame with 15%, 20%, & 25% centre &corner opening, which is
performed by using computer software STAAD-Pro from which different parameters are computed. In which it
shows that how infill panels increase the stiffness of the structure. While the increase in the opening percentage
leads to a decrease on the lateral stiffness of infilled frame. This paper highlights the importance of the presence
of the open first storey in the analysis of the building
OPTIMUM DESIGN OF SEMI-GRAVITY RETAINING WALL SUBJECTED TO STATIC AND SEISMIC...IAEME Publication
A 2D (Plain strain) wall‒backfill‒foundation interaction is modeled using finite element
method by ANSYS to find the optimum design based on the principle of soil-structure
interactions analyses. A semi-gravity retaining wall subjected to static and seismic loads has
been considered in this research. Seismic records which are obtained from the records of Iraq
for the period 1900-1988. The optimization process is simulated by ANSYS /APDL language
programming depending on the available optimization commands. The objective function of
optimization process OBJ is to minimize the cross-sectional area of the retaining wall. The
results showed that the optimum design method via ANSYS is a successful strategy prompts to
optimum values of cross‒sectional area with both safety and stability factors as compared with
other optimum design methods. Also, the results showed that the area of optimum section by
ANSYS method is lesser than the section area of the GAs algorithm , PSO, and CSS methods by
percentages are equal to 15.04%, 23.92%, and 25.33%; respectively, when
3.Additionally, from studying the effect of some parameters such as Compressive Strength of
Concrete (´
) and Yielding Strength of Steel ( on cross-sectional area and reinforced
area, is provided that the (´) and have small effect or do not effect on the value of crosssectional
area () and this is due to the lack of weight ratio of steel reinforcement to concrete
weight. Moreover, the yielding strength of steel has larger effect than compressive strength of
concrete in the reinforcement area.
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
Serviceability behavior of Reinforcement Concrete beams with polypropylene an...IJERA Editor
Serviceability Limit States (SLS) may lead to the design of concrete elements internally reinforced with Fiber Reinforced Polymer (FRP).In many types of concrete structure loss the serviceability due to wide cracks, number of cracks or large deflection is not uncommon behaviour in concrete structures or concrete beams.The flexural ductility affects the serviceability deflection of RC beams once flexural cracking take place.Imprvement will be focused on the use of polypropilene fibres , which is the subject of thispaper. The performance of concrete with fibers is judged by the flexural toughness obtained by load-deflection curves. The flexural toughness of concrete is depend on different types of fibersin use.Its tougness will be reperesent in the behaviour of RC memebres at failure. Sometimes, it is difficult to use the flexural toughness to judge the behavior of concrete structures under service load. The result of cracking on concrete beam due to the applied load and the method of loading to monitor and check the performance of concrete with different types of fiber arediscussed in this paper. The reductionin the dimension of cracks and the effect of energy disipations of polypropilene fibres will be the main aim of this research work.
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
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.
Survey of analysis and performance of ofdm signals in time and frequency disp...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
EXPERIMENTAL MODELING OF IN FILLED RC FRAMES WITH OPENINGIAEME Publication
Reinforced concrete frames are usually infilled with masonry walls but, in most designs, both the shear strength capacity of these walls and the contribution of the infill panel openings on the shear strength of the infilled frame, especially in critical cases of seismic loading are generally ignored. This paper reports the results of an experimental study of the influence of central openings in the infill on the sway stiffness of reinforced concrete plane frames. A series of 1:4 scaled structural models with opening ratios from 0 to 50 percent in steps of 10 percent were designed, constructed and tested in the study to obtain the load - displacement profiles.
Seismic evaluation of rc frame with brick masonry infill wallseSAT Journals
Abstract
Infill panels are widely used as partition walls as well as external walls of the building to fill the gap between RC frames. Non-structural member may provide considerable stiffness to the building and hence may improve the performance of the RC building during ground motions. But In most of the cases, the ignorance of this property of masonry in designing of the RC frame may get an unsafe design. There are two methods are used to determine the effect of ground motion. The effect of ground motion on RC frame building has been carried out by considering with and without the stiffness of infill wall. A comparative study is carried out with RC building using Equivalent Lateral Force method and Response Spectrum method. The masonry infill has been modeled as an equivalent diagonal strut element using Hendry formula. Pushover analysis is carried out on bare frame and frame with infill wall. The model has been generated using STAAD Pro and results obtained from the analysis are compared in terms of strength and stiffness with bare frame.
Keywords: Seismic evaluation, Response Spectrum, masonry infill, diagonal strut.
Analysis of rc frame with and without masonry infill wall with different stif...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.
Flexural behaviour of interior r.c.beam column joint with and without slab un...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.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Static Analysis of Masonry Infilled R.C.Frame With &Without Opening Including...IOSR Journals
Masonry infill is considered as a non-structural element in all type of buildings where masonry use.
But, masonry infill walls are mainly used to increase initial stiffness and strength of reinforced concrete (RC)
frame buildings. This Open First storey is also termed as “Soft Storey”. The upper storeys have brick infilled
wall panels with various opening percentage in it. In many cities of India, it is very common to leave the first
storey of masonry infilled reinforcement concrete (RC) frame building open preliminary to generate parking
space or any other usage in the first storey. Such buildings are highly undesirable in seismically active areas. In
the present study, it is an attempt to access the performance of masonry infilled reinforced concrete (RC) frames
with soft storey of with and without opening. In this paper, symmetrical frame of college building (G+5) located
in seismic zone-III is considered by modelling of initial frame. According to FEMA-273, & ATC-40 which
contain the provisions of calculation of stiffness of infilled frames by modelling infill as“Equivalent Diagonal
Strut Method”. Therefore, the infill panels are modelled as equivalent diagonal strut method. The error
involved in modelling such buildings as neglecting the presence of infills in the upper storeys, is brought out
through the study of an example building with different analytical models. This linear static analysis is to be
carried out on the models such as Strut frame with 15%, 20%, & 25% centre &corner opening, which is
performed by using computer software STAAD-Pro from which different parameters are computed. In which it
shows that how infill panels increase the stiffness of the structure. While the increase in the opening percentage
leads to a decrease on the lateral stiffness of infilled frame. This paper highlights the importance of the presence
of the open first storey in the analysis of the building
OPTIMUM DESIGN OF SEMI-GRAVITY RETAINING WALL SUBJECTED TO STATIC AND SEISMIC...IAEME Publication
A 2D (Plain strain) wall‒backfill‒foundation interaction is modeled using finite element
method by ANSYS to find the optimum design based on the principle of soil-structure
interactions analyses. A semi-gravity retaining wall subjected to static and seismic loads has
been considered in this research. Seismic records which are obtained from the records of Iraq
for the period 1900-1988. The optimization process is simulated by ANSYS /APDL language
programming depending on the available optimization commands. The objective function of
optimization process OBJ is to minimize the cross-sectional area of the retaining wall. The
results showed that the optimum design method via ANSYS is a successful strategy prompts to
optimum values of cross‒sectional area with both safety and stability factors as compared with
other optimum design methods. Also, the results showed that the area of optimum section by
ANSYS method is lesser than the section area of the GAs algorithm , PSO, and CSS methods by
percentages are equal to 15.04%, 23.92%, and 25.33%; respectively, when
3.Additionally, from studying the effect of some parameters such as Compressive Strength of
Concrete (´
) and Yielding Strength of Steel ( on cross-sectional area and reinforced
area, is provided that the (´) and have small effect or do not effect on the value of crosssectional
area () and this is due to the lack of weight ratio of steel reinforcement to concrete
weight. Moreover, the yielding strength of steel has larger effect than compressive strength of
concrete in the reinforcement area.
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
Serviceability behavior of Reinforcement Concrete beams with polypropylene an...IJERA Editor
Serviceability Limit States (SLS) may lead to the design of concrete elements internally reinforced with Fiber Reinforced Polymer (FRP).In many types of concrete structure loss the serviceability due to wide cracks, number of cracks or large deflection is not uncommon behaviour in concrete structures or concrete beams.The flexural ductility affects the serviceability deflection of RC beams once flexural cracking take place.Imprvement will be focused on the use of polypropilene fibres , which is the subject of thispaper. The performance of concrete with fibers is judged by the flexural toughness obtained by load-deflection curves. The flexural toughness of concrete is depend on different types of fibersin use.Its tougness will be reperesent in the behaviour of RC memebres at failure. Sometimes, it is difficult to use the flexural toughness to judge the behavior of concrete structures under service load. The result of cracking on concrete beam due to the applied load and the method of loading to monitor and check the performance of concrete with different types of fiber arediscussed in this paper. The reductionin the dimension of cracks and the effect of energy disipations of polypropilene fibres will be the main aim of this research work.
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
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.
Survey of analysis and performance of ofdm signals in time and frequency disp...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
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.
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.
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.
Fpga implementation of run length encoding with new formulated codeword gener...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
Performance analysis of dwdm based fiber optic communication with different m...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
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.
Synthesis of methyl, benzyl and pseudo halogeno co (iii) complexes of a dioxi...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.
A review on implementation of algorithms for detection of diabetic retinopathyeSAT 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
Optimization of workload prediction based on map reduce frame work in a cloud...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
Analysis of image steganalysis techniques to defend against statistical attac...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.
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.
An effective attack preventing routing approach in speed network in manetseSAT 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.
Effect of modulus of masonry on initial lateral stiffness of infilled frames ...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.
A study of r.c.c. beam column connection subjected to monotonic loadingeSAT Journals
Abstract
Beam and column where intersects is called as joint or Connection. The different types of joints are classified as corner joint, exterior
joint, interior joint etc. on beam column joint applying quasi-static loading .i. e. monotonic loading on cantilever end of the beam and
study of various parameters as to be find out on corner and exterior beam column joint i.e. maximum stress, minimum stress,
displacement and variation in stiffness of beam column joint can be analyzed in Ansys software ( Non-Linear FEM Software) The
various research studies focused on corner and exterior beam column joints and their behavior, support conditions of beam-column
joints. Some recent experimental studies, however, addressed beam-column joints of substandard RC frames with weak columns, poor
anchorage of longitudinal beam bars and insufficient transverse reinforcement. the behavior of exterior beam column joint is different
than the corner beam column joint.
Keywords: beam, column, corner, exterior, joint, monotonic load, quasi-static, varying stiffness
A study of r.c.c. beam column connection subjected to monotonic loadingeSAT Journals
Abstract
Beam and column where intersects is called as joint or Connection. The different types of joints are classified as corner joint, exterior
joint, interior joint etc. on beam column joint applying quasi-static loading .i. e. monotonic loading on cantilever end of the beam and
study of various parameters as to be find out on corner and exterior beam column joint i.e. maximum stress, minimum stress,
displacement and variation in stiffness of beam column joint can be analyzed in Ansys software ( Non-Linear FEM Software) The
various research studies focused on corner and exterior beam column joints and their behavior, support conditions of beam-column
joints. Some recent experimental studies, however, addressed beam-column joints of substandard RC frames with weak columns, poor
anchorage of longitudinal beam bars and insufficient transverse reinforcement. the behavior of exterior beam column joint is different
than the corner beam column joint.
Keywords: beam, column, corner, exterior, joint, monotonic load, quasi-static, varying stiffness.
Study of behaviour of composite beams with truss type shear connectoreSAT Journals
Abstract
Composite action of two concrete members is achieved by the interface shear transfer between the two members; this mechanism is of great significance. The interface shear carrying capacity is dependent on the surface properties and shear connectors provided. In the current research ATENA is used, it is FEM based software in which the interface properties between materials can be modeled to a great level of detail. In the present study the influence of angle of inclination, size and the depth of embedment of truss connector on the load carrying behavior is studied with the help of a beam model. The angles of inclination varied are 30o, 45o, 60o and 75o with varying bar diameters of 8mm, 10mm and 12mm. Angles between 60o to 75o are found most efficient with no significant changes when diameters are varied. The ultimate load for a given connector is found to be independent of the depth of embedment. Composite beams are also modeled to study the influence of cohesion and friction coefficient, and are compared with behavior of solid and non-composite beams.
Keywords: Truss shear connector, Composite slab, ATENA, Slab flexure test, Interface shear capacity
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.
Performance Based Evaluation of Shear Walled RCC Building by Pushover AnalysisIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Experimental Study, Simulation and Model Predictions of Recycled PET Strip-Re...IJERA Editor
This study presents results from a theoretical-experimental program of beams partially pre-stressed made with continuous recycled PET strip-reinforced concrete (plain concrete strength of 20 MPa). These studies mainly attempted to determine the stripinfluence in altering the flexural strength at first and final crack. Also the load-deflection, ductility, energy absorption capacity of the beams are observed and the studies can be used in predicting the flexural behavior of longitudinally reinforced concrete. The model theory assumes that concrete has a tensile load capacity different from zero, characterized by a uniaxial tensile stress-strain diagram. The need for non-linear geometric and the material models imply the use of numerical methods such as the finite element method; so that, a finite element analysis of reinforced concrete beam with strips-reinforced plastic is performed. The obtained results were compared with computer analysis and experimental data to corroborate the validity of the suggested method, showing that the theory also predicts correctly the post-cracking creep deformation.
Contents lists available at ScienceDirectPrecision Enginee.docxdonnajames55
Contents lists available at ScienceDirect
Precision Engineering
journal homepage: www.elsevier.com/locate/precision
Design and analysis of strut-based lattice structures for vibration isolation
Wahyudin P. Syama,⁎, Wu Jianweib,⁎, Bo Zhaob, Ian Maskeryc, Waiel Elmadiha, Richard Leacha
a Manufacturing Metrology Team, Faculty of Engineering, University of Nottingham, NG7 2RD, UK
b Ultra-Precision Optoelectronic Instrumentation Engineering Center, Harbin Institute of Technology, 150001, China
c Centre for Additive Manufacturing, Faculty of Engineering, University of Nottingham, NG7 2RD, UK
A R T I C L E I N F O
Keywords:
Additive manufacturing
Design
Lattice structures
Vibration isolation
Natural frequency
A B S T R A C T
This paper presents the design, analysis and experimental verification of strut-based lattice structures to enhance
the mechanical vibration isolation properties of a machine frame, whilst also conserving its structural integrity.
In addition, design parameters that correlate lattices, with fixed volume and similar material, to natural fre-
quency and structural integrity are also presented. To achieve high efficiency of vibration isolation and to
conserve the structural integrity, a trade-off needs to be made between the frame’s natural frequency and its
compressive strength. The total area moment of inertia and the mass (at fixed volume and with similar material)
are proposed design parameters to compare and select the lattice structures; these parameters are computa-
tionally efficient and straight-forward to compute, as opposed to the use of finite element modelling to estimate
both natural frequency and compressive strength. However, to validate the design parameters, finite element
modelling has been used to determine the theoretical static and dynamic mechanical properties of the lattice
structures. The lattices have been fabricated by laser powder bed fusion and experimentally tested to compare
their static and dynamic properties to the theoretical model. Correlations between the proposed design para-
meters, and the natural frequency and strength of the lattices are presented.
1. Introduction
Additive manufacturing (AM) allows almost infinite geometrical
design freedom [1], and the range and mix of potential materials is
increasing [2,3]. However, despite the benefits afforded with having
such freedom in design, there is a correspondingly larger design space
that can be difficult to navigate. In this paper, we demonstrate how
relatively simple design parameters can be used to reduce the design
space and pinpoint a near-optimum design.
AM lattices are popular because they exhibit various advantages
over solid stuctures and non-additively manufactured cellular solids.
AM lattices have all the advantages of cellular solids, for example, low-
mass and high impact energy absorbtion, and have an additional ad-
vantage: a high degree of design freedom. The freedom to exploit lattice
designs is a big advantage that .
seismic response of multi storey building equipped with steel bracingINFOGAIN PUBLICATION
Steel bracing has proven to be one of the most effective systems in resisting lateral loads. Although its use to upgrade the lateral load capacity of existing Reinforced Concrete (RC) frames has been the subject of numerous studies, guidelines for its use in newly constructed RC frames still need to be developed. In this paper the study reveals that seismic performance of moment resisting RC frames with different patterns of bracing system. The three different types of bracings were used i.e. X - bracing system, V - bracing system and Inverted V - bracing system. This arrangement helped in reducing the structural response (i.e. displacement, interstorey drift, Shear Forces & Bending Moments) of the designed building structure. An (G+6) storey building was modelled and designed as per the code provisions of IS-1893:2002. And linear analysis is been carried out in the global X direction. The analysis was conducted with a view of accessing the seismic elastic performance of the building structure.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...
Can fracture mechanics predict damage due disaster of structures
1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 104
CAN FRACTURE MECHANICS PREDICT DAMAGE DUE DISASTER
OF STRUCTURES?
Nagesh H.E1
, G. Appa Rao2
1
PhD Scholar, Structural Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai-
600036, India
2
Professor, Structural Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai-
600036, India
Abstract
This paper discusses shortcomings of existing code provisions for design of reinforced concrete structures, and need for
application of fracture mechanics in design of such structures. For a structure to perform satisfactorily in case of disastrous
incidents, care must be exercised at the time of design of structure itself. Fracture mechanics approach for design of structures
ensures rational design maintaining safety with reasonable safety margin. Currently, several national and international codes of
practice do not recognize the size effect on strength and serviceability of structures. In the design of structures with concrete, the
size effect needs to be incorporated to avoid sudden failures. Generally laboratory based tests have limitation on size of members,
which are relatively very small compared to actual large structures whose strength cannot be extrapolated. The incorporation of
effect of size and other fracture parameters can yield improvement in the design of members with better prediction of safety
margin.
Keywords: Fracture mechanics, Size effect, Minimum reinforcement, Ductility, Shear strength.
-------------------------------------------------------------------***-------------------------------------------------------------------
1. HOW SIGNIFICANT SIZE EFFECT IN
CONCRETE STRUCTURES?
According to the strength of materials approach, large size
and small size beams fail at same stress levels, if the given
material properties. But in practical the large size beams fail
at lower stress levels than small size beams. In designer
point of view, the most common examples for size effect
are, in bending test of concrete beam the strength decreases
with increase in beam depth. Shear strength of geometrically
similar concrete beams also found to be decreasing as the
size increases. Size effect in shear is more predominant than
in flexure. Overall it is noticed from experiments that as the
size increases there will be transition from ductile to brittle
failure, if all other properties maintained same. This change
in material properties with volume is known as size effect.
The main causes for size effect is (i) Statistical due to
material strength randomness, according to Weibull
statistical theory i.e. as the size increases, volume also
increases along with percentage of voids also increases
resulting in strength reduction because of material
heterogeneity. (ii) Energetic due to energy release which
causes stress redistribution, when a large crack or a large
fracture process zone (FPZ) containing damaged material
develops before the maximum load is reached and
discontinuities in flow of stress in case of cracks.
Quasibrittle materials like concrete exhibit two types size
effects that can be studied according to cohesive fracture
mechanics or (NLEFM), The size effect in failures occurring
(i) at macro-crack initiation, which is typical of plain
concrete. (ii) After large stable crack growth, which is
typical in reinforced concrete, especially shear in beams.
The latter is due to energy release associated with stress
redistribution caused by a large crack.
Fig 1 Size Effect according to strength criteria, linear and
nonlinear fracture mechanics
According to strength theory, the failure criterion is
expressed in terms of stresses or strains which is calculated
according to theories of elasticity and plasticity. The failure
condition is indicated by the condition σn = ft, where ft is the
direct tensile strength of concrete. σn is the nominal stress at
0
1
2
3
4
5
6
7
8
9
0 2 4 6 8 10
Nominal
stress
at
failure,
σn
Log (Size)
STRENGTH
LEF
M
NLE
FM
Most
existing
tests 1
2
2. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 105
failure characterizing the stress state at a certain critical
point in structure. For dimensionality purpose,
where, cn is the coefficient which is independent of
the size, shape and loading. P is the load, d is the
characteristic dimension and b is the thickness. The above
relationship between log (σn) vs. log (size) which is a non-
dimensional size parameter log (d/da), where‘d’ is the
characteristic dimension and ‘da’ is the maximum size of the
aggregate. It can be seen from Fig 1, according to the
strength criteria it is horizontal line, which is independent of
the size of member. In Linear Elastic Fracture Mechanics
(LEFM) failure criterion is expressed in terms of the energy
consumed per unit crack length increment and σn varies
inversely as √d. so the variation of log (σn) vs. log (size) is a
straight line with a slope of -1/2 as shown in Fig. 1. The true
size effect in concrete structures can be represented as a
gradual transition from the horizontal line to the inclined
straight line according to Non Linear Elastic Fracture
Mechanics (NLEFM).
2. PRESENT DESIGN BASIS
Presently all national and international codes of practice are
based on tests conducted on small size specimens at various
laboratories. The codes do not explain or limitations of its
application up to certain size and the same formulae are
being used to design large structures also without knowing
its limitations. The extrapolation should be well anchored in
a theory so that the practical results match well with the
extrapolated values.
Fig 2 Histogram of beam depth (number of test data vs. depth) Courtesy: Bazant and Yu (2005)
Figure 2 shows the histogram of the number of test data
versus beam depth, ‘d’ according to the database compiled
by subcommittee 445F of the American Concrete Institute
(ACI). The size effect is of practical concern mainly for
beam depths ranging from 1.0m to 15.0m. Unfortunately,
86% of all the available test data pertain to beam depths less
than 0.5 m. This highlights the importance of testing larger
size test specimens in laboratories rather than smaller size.
The extrapolation should be anchored to a theory in order to
ensure safe designs.
3. RESEARCH SIGNIFICANCE
Present design codes mainly based on strength and
serviceability aspects. Neglecting tensile strength of
concrete results in conservative designs. Failure of RC
beams according to the conventional strength or yield
criterion exhibit no size dependence, nor should the size of
the beam have any effect on its ductility. The effect of size
of member and ductility in the design of RC members can
be predicted by using fracture mechanics. The fracture
mechanics based research also shows that, there is a need to
test large size specimens in laboratories.
4. BACKGROUND
The first attempt recorded on use of fracture mechanics of
concrete was by Kaplan (1961) attempting the use of linear
elastic fracture mechanics (LEFM). It was confirmed that
the large size beams exhibit strong size effect on nominal
stress at failure, which is size independent on small beams
(Walsh, 1972). The first theoretical model for reinforced
concrete beam in flexure was by Carpinteri (1981, and
1984) adopted the principles of fracture mechanics to solve
the problem of a reinforced concrete beam with an initial
edge crack ‘a’ subjected to bending. According to this
0
50
100
150
200
0.0 0.1 0.3 0.4 0.5 0.6 0.8 0.9 1.0 1.1 1.3 1.4 1.5 1.7 1.8 1.9 2.0 2.2 2.3 2.4 2.5 2.7 2.8 2.9 3.0 3.2 3.3 3.4 3.6 3.7 3.8
Number
of
tests
Depth in (m)
Range of main practical interest for size effect
86% of Test Data
3. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 106
elementary model, moment and steel forces applied
remotely from the crack faces are superposed. The
assumption was that concrete behaves as a linear elastic
material and steel as a linear elastic-perfectly plastic. After
that many modifications and refined models are now
available. Bazant in his series of works showed the
significance of size effect in designing civil engineering
structures. Bazant demonstrated in theoretical model that
size effect mainly caused by stress redistribution and
localization of cracking damage associated with the release
of energy stored in the structure. Many theoretical models
and applications of size effect also contributed by Bazant. It
includes crack band model (1983), Bazant size effect law
(1984) and nonlocal softening damage models.
5. SIZE EFFECT ON DUCTILITY
The performance of structures due to loading effects of
earthquake, storms and other natural disasters mainly
depends on ductility of the members. Because ductility
ensures ductile failure which prevents sudden or brittle
failure that leads to sudden collapse. The following are some
of the investigations related to ductility and size effects in
beams.
Hillerborg (1990) made theoretical investigation of
rotational capacity of RC beams by applying fracture
mechanics concepts. It has been concluded that the
rotational capacity is nearly inversely proportional to the
depth of beam. Bigaj and Walraven (1993) investigated size
effect on rotational capacity of beams. They reported that
the members with small dimensions show much higher
plastic rotations than members with larger dimensions of
same characteristics. Carpinteri et al. (2009) developed new
model for the analysis of size-scale effects on the ductility
of RC beams in bending. They concluded that behavior
tends to become more brittle as beam depth increases. This
behavior is very well evidenced by a progressive reduction
of the beam rotation at failure.
Rao et al. (2008) derived ductility number from principles
of dimensional analysis, which is function of size of beam
(h), fracture energy (GF), yield strength of steel (fy),
modulus of elasticity of concrete (Ec), area of steel
reinforcement (As) and gross-area of cross-section
(Ag) . They concluded that the ultimate
flexural strength and ductility of RC beam decreases with
increase in size. The ductility factor increases with increase
in size for certain limit and again it decreases. Carpinteri et
al. (2013) outlined conditions for the structural design of RC
elements exhibiting ductile response. The decrease in one
parameter among depth (h), steel ratio (ρ), and yield
stress , or the increase in concrete tensile properties
or fracture energy (GF), all the other parameters being kept
constant, determines a transition from ductile response to
unstable tensile crack propagation. On the other hand, the
increase in h, ρ, and , or the decrease in ultimate
compressive stress or (Gc) all other parameters being
kept constant, produces a transition towards crushing failure
without steel yielding. In an overview it is noticed that as
size increases brittleness of the structure also increases.
Hence this phenomenon should be accounted while
designing any structures. Underestimation of ductility in
large scale specimens leads to transition from ductile to
brittle behavior, which is not desirable and it has to be
accounted in codes.
Figure 3. shows the plot of plastic rotation (φPL) versus
relative neutral axis position (x/d) with comparison of
Eurocode2 provision and numerical results of Carpinteri and
Corrado (2010). From the observation of plot it is clear that,
Eurocode 2 underestimates the plastic rotational capacity of
small size beam (0.2m depth) and overestimates the
rotational capacity of large size beam (0.6m and 0.8m
depth).
Fig 3 Plastic rotation vs. relative neutral axis
0
10
20
30
40
50
60
70
0 0.1 0.2 0.3 0.4 0.5
φ
PL(mrad)
x/d
0.2 m
0.4 m
0.6 m
0.8 m
EC2
4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 107
6. FRACTURE MECHANICS APPLICATIONS
IN DESIGN
Safe design of structure requires a valid mechanical model
and probabilistic analysis. Fracture mechanics provides a
scientific approach to define the failure of concrete. The
application of fracture mechanics to the design practice is
possible through the size effect. The two main applications
are presented here.
6.1 Minimum Reinforcement
Problems that can be solved using principles of fracture
mechanics is the provision of minimum reinforcement
because lightly reinforced beams are fracture sensitive.
Currently, various national and international codes of
practice provide empirical formulae for evaluation of
minimum reinforcement. Even though they are not rational
but performed satisfactorily for many years in design. These
codes disregard the nonlinear contribution of concrete in
tension and the size effects. They normally incorporated
compressive strength of concrete and yield strength of steel
as main parameters in the empirical formulae. Provisions in
American Concrete Institute (ACI) and Australian Standards
(AS) codes consider the compressive strength of concrete,
but British Standards (BS) and Indian Standards (IS) codes
do not. Australian Standards (AS) and Norway Standards
(NS) code defines minimum flexural reinforcement as a
function of size of member where as other codes do not.
Conventional method of evaluating cracking moment using
modulus of rupture (which is not strictly a material property)
for evaluating minimum reinforcement is empirical in
nature. The behavior of concrete in tension, crack initiation,
and crack propagation and fracture process zone are well
described in current fracture mechanics of concrete
approach. Such provisions ensure sufficient ductility in
flexural members by providing a reasonable margin of
safety between the first cracking and ultimate flexural loads.
The use of fracture mechanics of concrete enables rational
procedure to evaluate the optimum steel reinforcement
which ensures safe designs incorporating the size effect, and
other influencing parameters.
6.2 Evaluation of Shear Strength in Deep Beams
It is observed from experimental results of Kani (1967) that
about 40% of the ultimate shear strength reduction was
observed when the beam depth was increased from 300mm
to 1200 mm in deep beams without stirrups. Rao and
Sundaresan (2012) proposed equation for predicting shear
strength in deep beams incorporating size (depth) of the
beam and other influencing parameters. Bazant and Yu
(2009) showed that an increase of beam depth from 0.3 m to
1 m raises the shear failure probability of beams without
stirrups from (10-6
) to (10-3
) per lifetime. Yu and Bazant
(2011) demonstrated from experimental database and from
numerical studies that size effect on shear strength cannot be
suppressed by the presence of minimum or heavier stirrups.
For beams less than 1m, stirrups can mitigate significantly
but not in case of beams more than 1m. The current standard
ACI 318-2008 and other codes specifies for RC beams with
shear reinforcement, whether minimum or heavier, a size
independent shear strength equation. Hence these code
provisions need to be verified and adjusted to size dependent
shear strength.
Other applications such as brittle failures of concrete
structures (shear and torsion of R.C. beams with or without
stirrups, plain concrete flexure, slab punching, column
failure, bar embedment length, splices, bearing strength,
etc.) can also be studied by using fracture mechanics
principles.
7. CASE STUDIES
7.1 Failure of Tricell of Sleipner Oil Platform
This case study is about the failure of Sleipner an Oil
Platform, Norway in 1991. The tricell is 190m tall, structure
imploded under water head of 67 m, causing the platform to
sink. Investigation team outlines factors caused failure. (i)
The wall failed as a result of a combination of poor finite
element mesh (ii) insufficient anchorage of the
reinforcement in a critical zone. A separate investigation
documented a third contributing factor, the size effect in the
shear failure shown in figure. 4. which reduced the shear
capacity by about 40%. Caissons and shear failure of tricell
are shown in the figure.4.
5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 108
Fig 4 Sleipner oil platform caisson cells and failure of tricell
7.2 Failure of Koror-Babeldaob (KB) Bridge
(a)
(b)
(c)
Fig 5 Koror-Babeldaob (KB) Bridge (a) Before collapse (b)
and (c) After collapse
6. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 16 | ICPECDM-2014 | Dec-2014, Available @ http://www.ijret.org 109
Koror-Babeldaob (KB) bridge was built in 1977 in the
Republic of Palau. Collapse of bridge was occurred in 26th
September 1996 and investigation showed that erroneous
prediction of deflection due to creep and shrinkage, and
inappropriate remedial prestressing was major cause for
collapse. Consideration of size effect due to brittleness of
concrete would have prevented the collapse of above bridge.
The low safety margin and severity of size effect on large
size members causes catastrophic collapse. Size effect factor
for normal strength concrete can have a maximum value of
2.0, the size effect alone would be sufficient to cause the
collapse even though a safety margin related to error in the
design formulae and material randomness are included.
It is also remarkable to note that size effect must have
contributed to other disasters (e.g. bridges in Northridge.
Loma Prieta and Kobe earthquakes. Schoharie Bridge,
Shelby AF Warehouse, St. Francis Dam).
8. CONCLUSION
Fracture mechanics based designs give a promising safe
design of reinforced concrete structures incorporating size
effect and fracture properties of concrete. In real structures
like bridges, size of members is relatively large, so
brittleness also is high. If this behavior is properly
accounted for in the design, probability of failure in case of
any natural disaster can be avoided. This reveals that
introduction of size effect in the specifications of concrete
design codes is of the utmost practical importance.
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