Numerical Simulation of Column-End Damages of Reinforced Concrete Frames Caused by 2008 Wenchuan Earthquake in China

Abstract

This paper aims to investigate into the reasons for the widespread column-end damages of reinforced concrete (RC) frame buildings caused by the 2008 China Wenchuan earthquake. A six-story office building is used as the prototype building, and ten RC frames under different combinations of Seismic Intensity and Seismic Category are designed for the prototype building in accordance with the Chinese codes. Two joints of the second floor of each frame are selected for calculating the column-to-beam flexural strength ratio (CBSR), and the effects of the following four factors on the CBSR during a strong earthquake are analyzed: (1) the detailing practice of beam longitudinal reinforcement adopted in China; (2) slab participation in beam flexure; (3) reduction of joint concrete strength; and (4) variation of column axial force. The numerical results of CBSR indicate that the code requirement for the “strong column-weak beam” design in China is not sufficient for the RC frames designed for a Seismic Intensity of 0.2 g or lower to avoid column-end damages during a strong earthquake. Suggestions are made for improving the “strong column-weak beam” design of RC frames in China.

Keywords

axial force beams columns concrete strength flexural strength joints slab participation

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