Time-History Analysis of Reinforced Concrete Frame Buildings with Soft Storeys

Abstract

This research study investigates the change in dynamic characteristics of reinforced concrete moment-resisting frame buildings without and with fully infill walls. In addition, building models with partially infill walls have also been investigated. A set of different building models have been developed to perform the analysis as (1) bare frame (without infill walls), (2) frame with fully infill walls, (3) frame models with infill panels and soft storey located at base level, 3rd storey level, 6th storey level, 9th storey level, and 12th storey level. The equivalent diagonal strut method has been utilized in order to account for the stiffness and structural action of the masonry infill panels. Dynamic time history, using two ground motion records from near and far-fault regions, has been used to perform the seismic analysis of the considered model configurations. The selected two ground motion records have been scaled to meet the expected peak ground acceleration in Cairo zone. The two ground excitations are applied separately in two orthogonal directions. The structural software package ETABS has been used in developing the building models and performing the simulation analysis. Some selected numerical simulation results in terms of storey shear forces, lateral deflections, interstory drift ratios and overturning moments at each storey level are obtained for all the considered configurations and presented in comparative way. Based on the obtained time-history results, it has been found that the dynamic storey responses for bare frame model significantly differ from the responses obtained for both fully infill and partially infill frame models.