PERFORMANCE OF ECCENTRICALLY BRACED FRAMES UNDER THE ACTION OF LATERAL LOAD

Ramya A, Muthumani K, Nafeez Ahmed L

Abstract: Steel moment resisting frames experiences large lateral displacements during severe earthquake ground motions and require special attention to control lateral displacement and to limit the damage to nonstructural elements. Engineers started providing concentric braces to steel moment resisting frames to control the lateral displacement. It was observed in few earthquakes (Mexico 1985, Loma Prieta 1989, Northridge 1995) that such concentrically braced steel moment resisting frames did not perform well. The most severe damage was observed in frames where braces were proportioned to resist tension only, where connections were weaker than the braces attached to them, where braces framed into columns and where braces were inclined principally in one direction. The concept of incorporating braces eccentrically attracted the interest of researchers and the seismic performance seems to improve. This paper attempts to study the seismic performance of steel moment resisting frames with eccentric braces. The study concern with the enhancement of seismic performance by accomplishing eccentrically braced frames during undesirable earthquakes. Three steel framed structures (6 storey, 9 storey and 15 storey) are designed for the lateral force and their final performances of structure are evaluated through linear analysis using ETABS 2015 V.15.

Keywords: steel moment resisting frame, eccentric brace, seismic performance, lateral displacement

DOI: https://doi.org/10.15623/ijret.2015.0425059