Seismic Performance of Eccentrically Braced Frame (EBF) Buildings

Abstract

Eccentrically Braced Frames (EBF) have been researched upon and also implemented in practice worldwide, in the last three to four decades. However, the Indian Steel design code is still silent on this topic and does not provide any design provision for EBF. This paper is aimed to propose IS code compatible model design guidelines for EBF buildings. The guidelines are proposed after conducting a comparative study of design provisions from various national codes viz. American, European and New Zealand.The adequacy of proposed model guidelines is evaluated by modeling and designing suitable example buildings and subjecting them to non-linear pushover analysis. Suitable variations were introduced in examples by varying the number of storeys as five and ten; and designing the buildings as EBF with simple beam-column connections and moment resisting frame-EBF dual systems. The observations from analysis of different buildings are presented which indicate that EBF buildings demonstrated the ‘Life Safety’ performance level for the Design Basis Earthquake (DBE) but failed to achieve the desired ‘Collapse Prevention’ performance at the Maximum Considered Earthquake (MCE). Performance of buildings with dual lateral load resisting system, improved but was still not satisfactory along one direction at MCE hazard level. The paper discusses the efficacy of proposed model design guidelines for application of lateral loading and the potential issues in the satisfactory design of EBF buildings.