RC框架“强柱弱梁”设计的可靠度分析

Reliability Analysis of "Strong Column-Weak Beam" Design of RC Frame

"强柱弱梁"从概率意义上讲,就是对同一节点,柱出现塑性铰的概率要远小于梁出现塑性铰的概率;从结构体系来看,结构出现"层间破坏机构"的概率要远小于"整体破坏机构"的概率.本文分别从构件层次和结构体系层次出发,对不同抗震等级的RC框架柱和梁的抗震可靠度进行了分析,然后对一个5层框架结构形成"整体破坏机构"和"层间破坏机构"的概率进行了计算.结果表明,按现行抗震规范设计的抗震等级较低的结构,柱和梁的可靠指标相差不大,结构形成"层间破坏机构"与"整体破坏机构"的概率也相差不大,柱弯矩增大系数有待提高.

＂Strong column - weak beam＂ means that the generation probability of column hinge is far less than that of beam hinge for the same node, and the generation probability of ＂inter - story failure＂ mode is far less than that of ＂whole failure＂ mode. As viewed from the components and structural system, the reliability of columns and beams for different seismic - resistant grades is analyzed, and the generation probability of ＂inter - story failure＂ mode and ＂whole failure＂ mode is computed. The results show that for the lower seismic -resistant grade RC frame designed by the current seismic design code, the reliability index of columns is close to that of beams, and the generation probability of ＂interstory failure＂ mode and ＂whole failure＂ mode is similar too. The moment magnified factor of columns should be further improved.