Structural response of RC frame under seismic loading by varying inclination angle of cross bracing

Abstract

Structural performance is greatly affected by the use of concrete bracing in high seismic zone areas. A study representing the structural performance of a five-storey RC braced frame structure, by varying the inclination angle of concrete bracing, has been carried out by the use of numerical modelling for an earthquake load relating to a PGA value of up to 0.24 g. To investigate the problem, hypothetical models have been generated and analysed in SAP 2000 software using 3D modelling. Three models with different angle of bracing (i.e., < 45 degree, 45 degree and > 45 degree) are studied and compared with frame structure. Design considerations as per 'UBC-97' and 'BCP-2007' were used and response spectrum analysis has been carried out to observe the structural behaviour under dynamic loading. The parameters considered in this study are lateral displacements, inter-storey drifts, time period, base shear forces and axial forces and bending moments in ground floor columns. It has been concluded that the bracing angle affects the overall performance of structure. RC braced frame model with bracing angle less than 45 degree gives better seismic performance in terms of lateral drift and forces in structural members.