DETERMINATION OF SEISMIC UPGRADATION REQUIREMENTS OF RC FRAMED STRUCTURES

Abstract

Building codes are revised from time to time and the revision necessitates checking the adequacy of existing building for the demand as per the latest codes of practice. The code for criteria for earthquake resistant design of structures IS: 1893, was introduced in 1962. This standard was subsequently revised in 1966, 1970, 1975, 1984, 2002 and 2016. Conventional earthquake resistant design of buildings was aimed to provide minimum amount of lateral resistance to buildings and the methods for the estimation of base shear (seismic coefficient method) were modified with respect to the revisions.

The present study is carried out under two major heads (1) codal study and (2) analytical study.

In the codal study, a thorough study of different codes of IS: 1893 has been done. Seismic base shear and lateral load are computed using static method i.e. seismic coefficient method as per various versions of IS code 1893, in an MS Excel worksheet.

In the analytical study, a frame building having a plan dimension of 25m x 18m and height of 16m has been modelled. The building frame is modelled in STAAD PRO. the building is subjected to lateral forces as per various codes of previous times, calculated in codal study above. Various types of load combinations are applied according to latest available code for earthquake resistant design of buildings. Results of the building model, subjected to forces as per previous codes, are analyzed and compared to understand the effect of revision of seismic code on the adequacy of the buildings to sustain the earthquake forces and to appreciate upgradation requirements in them.