Seismic response of multi-storey reinforced concrete buildings with soft floor

Abstract

ABSTRACT The high-rise building in which ground storey consists of open space is known as building with soft floor. Such floor plays an important role in seismic performance of the building. This is due to the abrupt changes in lateral stiffness and strength caused by such storey. In this study, the seismic performance of RC buildings with soft storey using finite element method is investigated. The parameters considered in this research include the height of soft storey, irregularity in building plan dimensions, and the location of soft storey along the building height. An attempt is made in this research to find the optimum location of the soft storey through the building height to minimize its effect. In addition, the impact of applying simple strengthening techniques is investigated to promote structural safety without significant changes in the architectural and functional requirements of the building. The results include the effect of the investigated parameters on stiffness, displacement and storey drifts by using equivalent static load method and modal response spectrum method (MRS). P-Delta effect and cracked stiffness ratio are included in analysis. The results show that the factors such as increasing height of soft storey or increasing length-to-width ratio in the building have a significant effect on the stiffness and resistance. The results also demonstrate the effectiveness of the presence of shear walls for increasing stiffness and reducing displacements. Besides, providing a bracing system for retrofitting the building with soft storey has a positive effect on the behavior of these buildings.