Performance Evaluation of Vertical Irregular RC Building under Seismic Effect

Abstract

Structure can be classified as irregular if it has an irregular distribution of Mass, Stiffness and Strength in horizontal as well as in vertical direction. Different country codes have specified different limits for these irregularities. In reality many existing buildings contain irregularity due to aesthetic and functional needs. However, past records of earthquakes clearly show that the poor seismic performance of these structures is due to ignorance of the irregularity aspect while conducting the seismic design. The review of seismic design codes and Research studies show that location of irregularity has significant influence on the seismic response (Nassar and Krawinkler 1991; Al-Ali and Krawinkler 1998; Das and Nau 2003; Karavasilis 2008; Menon 2010). The cracking of structure members is a realistic phenomenon during seismic excitation and this results in changes of strength and stiffness(Priestley 2003; Paula and Priestley 1992).

The aim of the present study is to study mass and single setback irregularities with codal approach and estimation of seismic response quantities. These irregularities are considered according to the limits given in IS 1893: 2016 (Part-1).

In present work Linear static, Linear dynamic, Nonlinear time history analysis and Incremental Dynamic Analysis are applied on irregular building configurations. Nonlinear Time History Analysis gives more refinement and understanding of the structural response. In analysis 23 ground motions have been considered as per design spectra. Incremental Dynamic Analysis with 40 ground motions is also considered for evaluation of collapse capacity of irregular configurations of the building model.