钢筋混凝土框架延性破坏准则研究

Research on ductility failure criterion of reinforced concrete frames

结构试验研究和理论分析均表明框架变形能力强弱对抗震性能具有显著影响,已有框架破坏准则无法全面反映不同延性结构变形能力差异。文中提出了一种框架结构最大变形能力的定义和计算方法;通过研究柱轴压比、配箍率、结构变形能力、试验加载制度与整体性能退化之间的相互关系,提出了钢筋混凝土框架的延性破坏准则。通过对25榀平面框架试验的计算分析表明:考虑变形能力强弱的延性破坏准则能够实现钢筋混凝土框架的抗震性能量化表征,配箍率和承载力退化值对破坏指数具有显著影响,是否考虑配箍率和承载力退化4种情况对应的破坏指数平均值在0.763~0.919之间,标准差在0.206~0.404之间。根据14榀框架在不同破坏阶段的试验现象和破坏指数进行统计分析,给出了钢筋混凝土框架的延性准则破坏标准,研究成果可为抗震性能评估提供参考。

Experimental results and theoretical analysis show that deformation capacity of concrete frames had a significant influence on structural collapse.However,the existing collapse criteria can not reflect the deformation ability on collapse of frames.In the present work,the maximum deformation ability of concrete frame was defined and the calculation method was presented.A ductile failure criterion of reinforced concrete(RC)frame was estab⁃lished based on the investigation of the correlations of overall performance degradation of RC frames with axial com⁃pression ratio of columns,stirrup ratio,deformation ability of the frame and loading process.The damage experi⁃ments of 25 sets of RC frames were taken to verify the presented ductile failure criterion.Results indicated that the proposed ductile criterion can well quantitatively characterize the ductile damage of RC frames,and the stirrup ratio and the degradation value of bearing capacity have significant effects on the damage index.In the four cases of con⁃sidering either the stirrup ratio or the degradation value of bearing capacity,the calculated average value of the dam⁃age index were about 0.763~0.919 with standard deviations of 0.206~0.404.Furthermore,the damage evaluating standards of ductility criterion were proposed based on comprehensive consideration of the experimental phenomena at different damage processes and the calculated damage index from 14 sets of RC frames.The work can provide ref⁃erence for seismic evaluation of RC frames.