Evaluation of the seismic behavior of reinforced concrete structures with flat slab-column gravity frame and shear walls through nonlinear analysis methods

This paper presents an investigation of the seismic behavior of reinforced concrete (RC) structures in which shear walls are the main lateral load-resisting elements and the participation of flat slab floor systems is not considered in the seismic design procedure. In this regard, the behavior of six prototype structures (with different heights and plan layouts) is investigated through nonlinear static and time history analyses, implemented in the OpenSees platform. The results of the analyses are presented in terms of the behavior of the slab-column connections and their mode of failure at different loading stages. Moreover, the global response of the buildings is discussed in terms of some parameters, such as lateral overstrength due to the gravity flat slab-column frames. According to the nonlinear static analyses, in structures in which the slab-column connections were designed only for gravity loads, the slab-column connections exhibited a punching mode of failure even in the early stages of loading. However, the punching failure was eliminated in structures in which a minimum transverse reinforcement recommended in ACI 318 (2019) was provided in the slabs at joint regions. Furthermore, despite neglecting the contribution of gravity flat slab-column frames in the lateral load resistance of the structures, a relatively significant overstrength was imposed on the structures by the gravity frames.