A robust pushover analysis for multi-component seismic excitation: a new frame work
Source
Indian Institute of Technology, Gandhinagar
Date Issued
2016-01-01
Author(s)
Mathew, Rojan
Abstract
Seismic performance evaluation of a structure against seismic excitation is a crucial part of the
safety examination. Incremental Dynamic Analysis (IDA) is the best option for the performance
evaluation which is not popular among the practicing engineers. Nonlinear Static Pushover (NSP)
methods are approximate and reliable alternate for the time consuming and complex IDA. The
conventional NSP methods are based on pushing a structure with constant load profile, however it
is restricted to single mode response. In order to overcome these issues, NSP based on multiple
modal pushovers were introduced. Among the various NSP methods, Modal Pushover Analysis
(MPA) is one of the popular method. But the multiple modal methods are not able to predict the
plastic hinge formation due to individual modal pushovers and the hinge formation is not directly
related to the mode wise distribution.
This thesis presents a new robust pushover (Alternate pushover analysis, APA) method which
keeps the simplicity of conventional methods and gives a reliable solution. It is based on a single
pushover and multiple modal target displacement calculations. The proposed pushover method is
extended to buildings subjected to bidirectional and the multi-directional excitations including the
torsional component.
The APA is applied to two reinforced concrete buildings designed as per Indian standards, one is
symmetric and other is asymmetric in nature. Seismic demands of these buildings under
unidirectional, bidirectional and multidirectional including torsional components are calculated
using the proposed Alternate pushover analysis (APA). The estimated demands by APA is
compared with the benchmark solution obtained from nonlinear time history analysis (NLTH) as
well as the predictions from MPA. It is demonstrated that the proposed APA is effectively
calculating the seismic demands in all the cases.
safety examination. Incremental Dynamic Analysis (IDA) is the best option for the performance
evaluation which is not popular among the practicing engineers. Nonlinear Static Pushover (NSP)
methods are approximate and reliable alternate for the time consuming and complex IDA. The
conventional NSP methods are based on pushing a structure with constant load profile, however it
is restricted to single mode response. In order to overcome these issues, NSP based on multiple
modal pushovers were introduced. Among the various NSP methods, Modal Pushover Analysis
(MPA) is one of the popular method. But the multiple modal methods are not able to predict the
plastic hinge formation due to individual modal pushovers and the hinge formation is not directly
related to the mode wise distribution.
This thesis presents a new robust pushover (Alternate pushover analysis, APA) method which
keeps the simplicity of conventional methods and gives a reliable solution. It is based on a single
pushover and multiple modal target displacement calculations. The proposed pushover method is
extended to buildings subjected to bidirectional and the multi-directional excitations including the
torsional component.
The APA is applied to two reinforced concrete buildings designed as per Indian standards, one is
symmetric and other is asymmetric in nature. Seismic demands of these buildings under
unidirectional, bidirectional and multidirectional including torsional components are calculated
using the proposed Alternate pushover analysis (APA). The estimated demands by APA is
compared with the benchmark solution obtained from nonlinear time history analysis (NLTH) as
well as the predictions from MPA. It is demonstrated that the proposed APA is effectively
calculating the seismic demands in all the cases.
Subjects
Incremental Dynamic Analysis
Modal Pushover Analysis
Alternate Pushover Analysis
Nonlinear Time History Analysis
Torsional Component