INFLUENCE OF DIAPHRAGM ACTION UPON THE SEISMIC RESPONSE OF HIGH RISE MOMENT RESISTING BUILDING FRAMES

Diaphragm or horizontal bracing system is a horizontal system transmitting lateral forces to the vertical lateral load resisting elements. Under lateral loading floor slabs in reinforced concrete building perform as diaphragms to transfer lateral forces to load resisting frames. The objective of present study is to evaluate how a structure behaves when the reinforced concrete slabs are included in the structural analysis. In current study, two regular building model having 6 bays in each principle direction, each bay of 15ft length. In this way the plan dimensions become 90ft x 90ft.Total stories are 10, each having a height of 11ft except the plinth level which is 10ft in height .In this way the total height of the structure becomes 109ft. Diaphragms are modeled as rigid elements, thus the effect of their in plane movement relative to the vertical lateral load resisting system is neglected. It was found that the considering the effect of slabs in the structural analysis of case study buildings will give smaller values of storey displacements & storey shears, larger values of support reactions, column reinforcement & torsional forces transferred to beams, a mixed behavior for modal time period etc.