A Simplified Incremental Dynamic Analysis Procedure Using SAP2000

Abstract

Among several methods available for evaluating the seismic capacity and demand of structures, nonlinear dynamic procedures (NDP) provide the most reliable results. One such parametric analysis method is incremental dynamic analysis (IDA) which is emerging as an accurate tool in the field of performance-based earthquake engineering (PBEE). Despite the fact that IDA produces the most realistic results, complexities of the procedure as well as different software and system configuration required render it to be a computationally expensive method that is considered mostly for high cost and important structures and motivates less to be resorted to for general building structures. Compared to different sophisticated software required for scaling time histories and performing IDA, SAP2000 being a more commonly used tool, provides a better alternative for structural engineers to analyse buildings by IDA method. The paper elaborates a simplified step by step procedure to carry out IDA in SAP2000, scaling the IM within SAP2000 itself, thus eliminating the requirement of an additional software for scaling the time histories. The paper also elucidates interpretation of the desired performance point from the IDA curves, studying the seismic behaviour of buildings by contemplating the behaviour of IDA curves and generation of drift profiles along the building height when subjected to the increasing intensity measure (IM). As a step by step narrative, the paper can serve as a useful guide to perform IDA in SAP2000.