设置少量钢支撑钢筋混凝土框架结构抗震设计原理与设计方法研究

Site damage investigations of building structures after earthquake indicate that the existance of few steel braces or cast-in-place reinforced concrete (RC) staircases in a RC frame structure can significantly increase seismic resisting capacity of the structure. A new structure system called RC frame structure with few steel braces(RCFSFSBs) has been proposed in this research proposal. By setting few steel braces, the lateral stiffness of a RC frame structure can be increased and its seismic resisting behavior will be impoved. However, studies on the seismic design principle and design method for this new RCFSFSBs system are limited. In this study, following measuremens will be carried out. Several sets of typical RCFSFSBs structure models within different high seismic precautionary intensity areas will be analyzed and designed following the requirements of Code for Seismic Design of Buildings GB 50011-2010. Dynamic response simulations of such typical RCFSFSBs structures will be conducted systematiclly as well. A 1/2 scale RCFSFSBs structure model will be designed, constructed and loaded to failure. Based on these theoretical and experimental test results, the horizontal shear force and the overturn moment distributions between the steel braces and the RC frame structure members will be compared and studied. The characteristic parameters for the steel braces under different seismic requirements will be figured out. The lateral load resisting mechanism and different failure modes for such a structure system will be pointed out and deeply interpreted. Some quantitative measurements on how to set the steel braces, the requirements on mechanical properties of the steel braces and their end connecting joints between the steel brace and the RC frame structure member will be defined. A new type steel brace with different detailing and its connection method to RC frame member will be proposed and some full scale specimens of this new brace and its connection joints will be loaded to failure to verify the relibility and the workability of the proposed steel brace design method and its construction detail. When these jobs have been finished, a seismic design method and some related construction detailing requirements will be proposed.

震害调查发现，框架结构中柱间支撑或现浇楼梯可以提高结构的抗震能力。本项目提出设置少量钢支撑钢筋混凝土框架结构体系的概念，在钢筋混凝土框架结构中设置少量钢支撑，从而提高结构的抗侧刚度与抗震能力，但是，对这种体系的抗震设计原理与设计方法缺乏研究。本项目拟通过对高烈度区典型钢筋混凝土框架结构设置少量钢支撑后地震响应全过程的模拟分析，对设置少量钢支撑钢筋混凝土框架结构缩比模型模拟地震往复加载试验与分析，研究支撑与框架之间水平剪力与倾覆力矩分担率的变化规律以及支撑力学参数变化对结构体系抗震性能的影响，揭示水平地震作用下这种结构体系的传力机制与破坏特征，提出钢支撑设置的量化界定指标与满足抗震设计目标时对钢支撑及其端部连接的要求；完成新型钢支撑及其与框架连接节点试件的加载试验与分析，验证新型钢支撑及连接节点设计方法与构造措施的有效性，基于上述研究分析，提出这种结构体系的抗震设计方法与相关构造措施建议。

在RC框架结构中设置少量钢支撑可以提高其安全储备和抗震防倒塌能力。本项目围绕少钢支撑RC框架结构的定义和抗震设计方法，主要研究工作有：1）基于OpenSEEs平台完成了系列RC梁、RC柱、RC框架结构和带钢支撑RC框架结构的有限元建模与弹塑性有限元建模与分析标定，基于多个典型RC框架结构及少钢支撑RC框架结构的分析和性能化评估，借鉴少量剪力墙框架结构的定义方法，提出了少钢支撑RC框架结构的定义：在规定的水平力作用下，设置钢支撑的框架结构中框架底部所承担的整体地震倾覆力矩大于结构总地震倾覆力矩的50%但不超过70％，且钢支撑后对原框架结构抗侧刚度的提高幅度不超过40%，钢支撑满足小震不屈曲（屈服）大震不断裂，该定义与《建筑抗震设计规范》GB50011中对钢支撑RC框架结构的定义相容。2）完成了6度到9度共6种典型抗震设防烈度区分别设计的RC框架结构和少钢支撑RC框架结构的设计以及基于能力谱法方法的抗震性能评估和基于IDA的结构易损性分析，结果表明提出的设计方法是有效的。提出了对钢支撑与RC框架的抗震性能需求。3）完成了9个不同钢支撑试件与2个后装套管式新型屈曲约束支撑的试验研究与分析，得到优先采用圆钢管支撑的建议，提出了满足设计性能要求时对圆钢管径厚比与方钢管宽厚比的设计方法建议。验证了提出的后装套管式新型屈曲约束支撑能满足设计要求。4）提出了少钢支撑RC框架结构的设计方法建议。RC框架结构设置少量钢支撑的性能目标是：改变纯RC框架结构的受力模式及破坏次序，形成双重抗震防线；提高结构的抗侧刚度，控制最大层间位移角；提高结构的抗震防倒塌能力。建议了少钢支撑RC框架结构相关设计方法建议。