我国混凝土框架结构强柱弱梁措施的实际控制效果

为了识别强柱弱梁措施的实际抗震控制效果,对影响框架结构梁、柱端抗弯能力及二者相对强度的因素进行了分析归纳。严格按中国规范设计出5个不同地震烈度分区的规则平面框架结构,考察了这些结构在采取强柱弱梁措施后其柱、梁之间的实际强度级差系数及其规律,对这些框架进行了多波输入下的非弹性动力反应分析。结果表明,在罕遇地震下,9度区(一级抗震等级)框架形成了抗震性能良好的梁铰机构;而8度区二级抗震等级和7度区三级抗震等级的框架形成了以柱铰为主或柱铰偏多的梁、柱铰混合机构。分析结果揭示出,在现行强柱弱梁措施的调控下,不同抗震等级的框架结构在强震下所形成的塑性耗能机构存在明显差异,并可能导致在抗震安全水平上的不一致性。

Actual Control Effect of Strong-column and Weak-beam Measures of Reinforced Concrete Frame Structures in China

To verify the actual control effect of the strong-column and weak-beam measures,the factors influencing bending capacities of columns and beams and their relative strengths are analyzed and summarized.Five regular reinforced concrete frames are designed conformed to the Chinese code in different seismic fortification intensity.The actual strength hierarchy between columns and beams are investigated after the columns enhanced.The nonlinear dynamic response analysis of these frames under multi-wave input is carried out.The results show that under major earthquake,the frame of seismic grade 1 in earthquake intensity 9 region forms a beam-hinge mechanism with satisfactory seismic performance,and the frames of seismic grade 2 in earthquake intensity 8 region and seismic grade 3 in earthquake intensity 7 region form column-hinge-dominated mechanisms or ones with majority of column-hinge.The results show the distinct difference of plastic energy-dissipated mechanisms of frames in different seismic grades under strong motions and the inconsistence in anti-earthquake safety level between these structures,which could be a reference for the code administrative group.