考虑压拱和悬链线效应的RC框架结构反应修正系数研究

The design seismic force is determined by a single structural response modification factor to reduce the elastic responses under the design intensity in our currently Code, without considering the influences of different inelastic energy dissipation capacities of different structures. What’s more, compressive arch and catenary action aren’t taken into account in calculation theory of redundancy coefficient which is partial factor of response modification factor. Reinforced concrete frames are the research object of this project, the fined numerical simulations of RC frame structures which can better simulate the deterioration of structural components are carried out. The modeling approach and analysis results are verified and validated by pseudo-static test data for RC frame structure. Experimental study and numerical simulation are combined to reveal compressive arch and catenary mechanism. Then deterministic and probabilistic formula of redundancy coefficient considering the effects of compressive arch and catenary action are evaluated. Furthermore, the quantification and probabilistic assessment of structural response modification factors are studied. Seismic design response spectrum for reinforced concrete frames is suggested. The results from above research can provide the theoretical supports for the improvement of the seismic influence coefficient curves under minor earthquakes in the current Chinese seismic code.

我国抗震设计规范隐含取一个统一的反应修正系数值折减设防烈度下结构产生的弹性力来确定设计地震作用，而没有区分不同结构体系非弹性变形能力的差别，且反应修正系数的子项冗余度系数也未考虑压拱和悬链线效应。本项目以钢筋混凝土框架结构为研究对象，建立考虑性能退化的结构精细化非线性有限元模型，利用结构拟静力试验对有限元模型进行验证和参数校准，采用试验研究和数值模拟相结合的方法揭示梁的压拱和悬链线机理，进而提出考虑压拱和悬链线效应的冗余度系数的确定性和概率计算方法，进一步研究结构反应修正系数的合理取值及概率评定方法。提出适合钢筋混凝土框架结构的设计反应谱，为我国抗震规范中多遇地震影响系数曲线的修正提供理论支持。

压拱和悬链线效应机理是确定结构反应修正系数子项冗余度系数的关键科学问题。本项目采用试验和数值模拟相结合的方法研究了考虑压拱和悬链线效应的结构反应修正系数。项目的主要研究内容和成果如下：.（1）以钢筋混凝土框架结构为研究对象，建立了考虑性能退化的结构精细化非线性有限元模型，利用结构拟静力试验对有限元模型进行了验证和参数校准，获得完好结构的反应修正系数。.（2）对两榀1：2 比例的单层四跨RC平面框架结构，进行了压拱和悬链线机理实验，得到了RC框架荷载-位移关系曲线。分析表明梁上部纵向受力钢筋是否截断对悬链线机制作用阶段的抗倒塌能力影响较大，梁上部纵向受力钢筋未截断时，结构延性和峰值抗力分别提高了42%和66%。.（3）采用ABAQUS/CAE建立数值分析模型，模拟了RC框架竖向荷载作用下经历弹性阶段、压拱效应阶段以及悬链线机制作用阶段的倒塌全过程，分析得到了这三个阶段的耗能，从而得到考虑压拱和悬链线效应的结构绝对冗余度指标。.（4）采用位移能力需求法对完好结构反应修正系数进行了概率评定。进一步采用相对冗余度指标对完好结构反应修正系数进行了修正，得到了考虑压拱和悬链线效应的结构反应修正系数，给出了修正的地震影响系数曲线。