Comparison of Seismic Performance of Braced and Unbraced frames

Abstract

Earthquakes are nature’s most dangerous and unpredictable calamities and the source of severe damage to structure. The deteriorating effects of major earthquakes have harshly affected human lives and economies of states during the last decade. Past events have shown that it is not the earthquake but the response of structure that contributes to the damage induced. Pakistan has also seen some irreparable damage after the Kashmir Earthquake (2005). In order to tackle with seismic forces, several construction and retrofitting techniques have been used such as cross bracings, enhanced confinement using FRP sheets, concrete beam haunches etc. In Pakistan, a large stock of buildings exist which was not designed to cater for seismic load. Concrete bracing are an easy solution for attaining seismic strength and preventing damage from seismic loads. Concrete bracings are economical, less space consuming and can be designed to the meet required strength and stiffness criteria. In this study, effect of stiffness and location of bracing members on seismic performance of concrete structures is compared with that of unbraced frames using STAAD Pro. In order to determine optimized bracing arrangement. The performance of various bracing is also compared. The results show that the bracing system improves seismic performance of reinforced concrete frames and the extent of improvement depends upon the stiffness and location of the bracings . These results are available for different organizations and educational institutes to be used for