The Effects of pounding on the behavior of reinforced concrete frame structures in seismic zone 2B

Abstract

Pounding between adjacent buildings is a common phenomenon, which can be observed during moderate to high ground shakings that can result in structural damage and even loss of life. As this phenomenon is related to the life safety, therefore, it is imperative to consider it in the modelling stage of structural analysis and design. The current study is intended to evaluate, numerically, the effect of pounding phenomenon in RC frame structures. Threedimensional models of two hypothetical buildings are analyzed by subjecting to three ground acceleration histories that are scaled and matched with BCP-SP07 design spectrum. The analysis results such as interstory drift, maximum displacement, pounding forces, and their effects on bending moment, axial forces, and shear and torsional forces in structural members are compared. The results show that pounding forces decrease with the increase in gap size and are dominant in top five stories with maximum force at the top floor level. Pounding increases displacement up to 2 times and acceleration up to 240 times as compared to the case without pounding. Pounding increases the axial forces up to 250 times and bending moment up to 2 times in the beams parallel to colliding forces. Similarly, the shear forces and torsional moments are almost doubled as a result of pounding. Finally, a 20-story building consists of four blocks separated by 3-inch expansion joints is modelled combinedly in ETABS and analyzed to see the effect of pounding. Based on the results, it is concluded that pounding must be considered at the modelling stage of the design to account for the forces induced in the structural members.