25-10-2016, 12:44 PM
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Abstract
The lateral response of framed structure can be improved by placing shear wall judiciously in the plan of the structure. Most of the residential building is un-symmetrical due to functional necessity. It is proposed to carryout nonlinear static analysis (Pushover Analysis) for high rise building in zone IV. The nonlinear static analysis gives a better understanding and more accurate seismic performance of buildings and damage or failure at the element level. Nonlinear static pushover analysis of the model is presented by uniform acceleration of lateral load pattern. The relationship curve between base shear and top displacement of structure and the demand curve for the zone IV region will lead to performance point. The provision of shear wall and the change in performance level can be studied using SAP2000.
I. Introduction
Pushover analysis in RC structure is an approximate analysis method in which the structure is subjected to monotonically increasing lateral forces with an invariant height-wise distribution until a target displacement is reached. Pushover analysis consists of a series of sequential elastic analysis, superimposed to approximate a force-displacement curve of the overall structure. A two or three dimensional model which includes bilinear or tri-linear load-deformation diagrams of all lateral force resisting elements is first created and gravity loads are applied initially. A predefined lateral load pattern which is distributed along the building height is then applied. The lateral forces are increased until some members yield. The structural model is modified to account for the reduced stiffness of yielded members and lateral forces are again increased until additional members yield. This process is continued until a control displacement at the top of building reaches a certain level of deformation or structure becomes unstable. The roof displacement is plotted with base shear to get the global capacity curve.
Placing of shear wall in RC structure gives a more sufficient strength and deformation capacity to resist the lateral load. The pushover is compared where shear is economical and more effective performance in lateral seismic.
II. Objective
1. To study the performance of lateral seismic performance in pushover analysis.
2. Comparison and effective study of placing of shear wall.
V. Methodology
1. SAP2000 nonlinear behavior is assumed to occur within a structure at concentrated plastic hinges. The default types include an uncoupled moment hinges, an uncoupled axial hinges, an uncoupled shear hinges and a coupled axial force and biaxial bending moment hinges.
2. Control node is the node used to monitor displacements of the structure. Its displacement versus the base-shear forms the capacity (pushover) curve of the structure.
3. Developing the pushover curve which includes the evaluation of the force distributions. To have a displacement similar or close to the actual displacement due to earthquake, it is important to consider a force displacement equivalent to the expected distribution of the inertial forces. Different forces distributions can be used to represent the earthquake load intensity
4. The control is pushed to reach the demand displacement which represents the maximum expected displacement resulting from the earthquake intensity under consideration.
5. Evaluation of the performance level: Performance evaluation is the main objective of a performance based design. A component or action is considered satisfactory if it meets a prescribed performance.
VIII. Conclusions
1. Placing of shear wall results a huge decrease of base -shear and displacement.
2. The performance based seismic design obtained by above procedure satisfies the acceptance criteria for immediate occupancy and life safety limit states for various intensities of earthquakes.
Abstract
The lateral response of framed structure can be improved by placing shear wall judiciously in the plan of the structure. Most of the residential building is un-symmetrical due to functional necessity. It is proposed to carryout nonlinear static analysis (Pushover Analysis) for high rise building in zone IV. The nonlinear static analysis gives a better understanding and more accurate seismic performance of buildings and damage or failure at the element level. Nonlinear static pushover analysis of the model is presented by uniform acceleration of lateral load pattern. The relationship curve between base shear and top displacement of structure and the demand curve for the zone IV region will lead to performance point. The provision of shear wall and the change in performance level can be studied using SAP2000.
I. Introduction
Pushover analysis in RC structure is an approximate analysis method in which the structure is subjected to monotonically increasing lateral forces with an invariant height-wise distribution until a target displacement is reached. Pushover analysis consists of a series of sequential elastic analysis, superimposed to approximate a force-displacement curve of the overall structure. A two or three dimensional model which includes bilinear or tri-linear load-deformation diagrams of all lateral force resisting elements is first created and gravity loads are applied initially. A predefined lateral load pattern which is distributed along the building height is then applied. The lateral forces are increased until some members yield. The structural model is modified to account for the reduced stiffness of yielded members and lateral forces are again increased until additional members yield. This process is continued until a control displacement at the top of building reaches a certain level of deformation or structure becomes unstable. The roof displacement is plotted with base shear to get the global capacity curve.
Placing of shear wall in RC structure gives a more sufficient strength and deformation capacity to resist the lateral load. The pushover is compared where shear is economical and more effective performance in lateral seismic.
II. Objective
1. To study the performance of lateral seismic performance in pushover analysis.
2. Comparison and effective study of placing of shear wall.
V. Methodology
1. SAP2000 nonlinear behavior is assumed to occur within a structure at concentrated plastic hinges. The default types include an uncoupled moment hinges, an uncoupled axial hinges, an uncoupled shear hinges and a coupled axial force and biaxial bending moment hinges.
2. Control node is the node used to monitor displacements of the structure. Its displacement versus the base-shear forms the capacity (pushover) curve of the structure.
3. Developing the pushover curve which includes the evaluation of the force distributions. To have a displacement similar or close to the actual displacement due to earthquake, it is important to consider a force displacement equivalent to the expected distribution of the inertial forces. Different forces distributions can be used to represent the earthquake load intensity
4. The control is pushed to reach the demand displacement which represents the maximum expected displacement resulting from the earthquake intensity under consideration.
5. Evaluation of the performance level: Performance evaluation is the main objective of a performance based design. A component or action is considered satisfactory if it meets a prescribed performance.
VIII. Conclusions
1. Placing of shear wall results a huge decrease of base -shear and displacement.
2. The performance based seismic design obtained by above procedure satisfies the acceptance criteria for immediate occupancy and life safety limit states for various intensities of earthquakes.