中美规范RC剪力墙抗震设计对比研究

Comparative study on seismic design of RC shear walls between Chinese and U. S. codes

本文对比中国和美国规范关于RC剪力墙抗震设计的规定。对比表明,两国规范关于RC墙正截面承载力和斜截面承载力计算、以及混凝土强度、最小墙厚、分布钢筋、轴压比和剪力限值等构造要求均相近。但美国规范对于RC墙的变形能力要求显著高于中国规范。对高轴压比的一字形墙,美国规范对约束边缘构件沿墙肢长度和配箍的规定高于中国规范;美国规范对于T形墙腹板约束边缘构件沿墙肢长度的规定远大于中国规范。RC墙的数值模拟分析表明,分别按照中美规范设计的高轴压比一字形墙,其极限位移角可达到各自规范规定的变形能力要求;对于高轴压比T形墙,当腹板受压时,按美国规范设计的墙的极限位移角可达到0.03,而按中国规范设计的墙的极限位移角仅为0.008,尚未达到中国规范对于RC墙变形能力要求。本文提出了T形墙约束边缘构件的设计建议。

This paper compares the seismic design provisions of RC shear walls between Chinese and U. S. codes.It is found that two sets of codes have similar design on the flexural strength and shear strength of RC walls,and similar requirements on the details,for example,concrete strength,wall thickness,distributed reinforcement,and limits for axial force ratio and shear force. However,the U. S. codes specify much larger deformation capacity on RC walls relative to the Chinese codes. For the rectangular-shaped wall under high axial force ratios,the U. S.codes specify the special boundary elements with larger extent and larger amount of transverse reinforcement than the Chinese codes. For the T-shaped wall under high axial force ratios,the U. S. codes require much larger extent for the special boundary elements in the free end of the web than the Chinese codes. Numerical analyses on RC walls indicate that the rectangular-shaped walls under high axial force ratios,which are designed by two sets of codes,reach the deformation capacity required by those codes,respectively. For the web in compression,the Tshaped wall under high axial force ratios,which is designed by the U. S. codes,can reach the 0. 03 drift ratio;while the T-shaped wall by the Chinese codes has the ultimate drift ratio of 0. 008,which can not satisfy the Chinese code requirement. In addition,the paper proposes the design recommendation on the special boundary elements of T-shaped walls.