EFFECTS OF BRACING SYSTEM ON MULTISTORYED STEEL BUILDING

Abstract

In recent years, steel construction has shifted from moment-resisting frames to concentric braced frames in regions of highly seismic prone area. Bracing element in structural system by providing more stiffness plays a vital role in structural behaviour to resist earthquake forces. Concentric bracing is one of the most common lateral load resistant systems in building frames due to their manufacturing simplicity and economy. In this work, different types of bracing (X bracing, Inverted V bracing, K bracing, V bracing, Forward bracing, Backward bracing ) have been analysed and comparison has been made on the basis of maximum lateral displacement at each floor level due to seismic and wind loading. The main parameters considered to compare the seismic performance of buildings were bending moment, shear force, story drift, storey shear and concluded that the braced building of the storey drift decreases as compared to the unbraced building which indicates that the overall response of the building decreases, the displacement of the building decreases depending upon the different bracing system employed and the bracing sizes. In the present study, a 20 storey steel frame structure is analysed. For this purpose, seven different models were generated by changing the bracing system in steel frame and analysed for wind and seismic forces. It may be concluded from this study that bracing element will have very important effect on structural behaviour under seismic loading. Most suitable bracing system is Backward bracing system. Lateral displacement at top floor is reduced approximately 50% for Backward braced in frame structure compared to without bracing system.