基于损伤控制的功能可恢复RC框架结构抗震性能研究

In contrast to conventional ductile reinforced concrete (RC) building structures in which RC members are intended to sustain damage and dissipate energy during major earthquakes, various specifically designed energy dissipating devices have been extensively used to control the structural damage of building structures in the past decades, which enable the development of efficient while economic approaches to performance-based earthquake engineering and earthquake resilience. This research project proposes an innovative buckling restrained braced RC frame structural system with the buckling restrained braces (BRBs) configured in a diamond shape to form an 'energy dissipating module' for a single span-single story concrete frame. The proposed diamond-shaped energy dissipating module is expected to impose little tensile force on steel-to-concrete connection because of the unique configuration of the BRBs. All steel-to-concrete connections in a single module are located at mid-span or mid-height of the RC beams and columns so that the local behavior of the connection is independent of that of the potential damage zones of the concrete frame. These features make the proposed system a promising solution for enhanced earthquake resilience. The proposed system can be applied in both new buildings and seismic retrofit of existing buildings. In particular, it requires less effort to install the proposed energy dissipating module on site as compared to conventional methods of connecting steel braces to existing concrete frame. The seismic performance of the proposed structural system regarding its local and global damage mechanism and characteristics, peak seismic responses and residual displacement are examined through both experimental and numerical investigations. Emphasis is given to the earthquake resilience of the proposed system. Relevant design recommendations are also established.

传统延性设计的钢筋混凝土（RC）结构虽然也强调对结构损伤机制的控制，但其预期损伤部位同时也是主要承重构件，震损后难以修复，功能可恢复性差，应对地震风险的经济性差。以在整体结构中采用耗能减震子结构为特征的损伤控制技术是实现基于性能抗震设计和功能可恢复结构的经济有效途径。本项目提出一种新型的菱形布置防屈曲支撑RC框架结构体系。该体系中的防屈曲支撑对钢筋混凝土构件几乎没有法向拉力作用，且连接节点远离RC框架梁端、柱端等预期塑性铰区，有助于减轻防屈曲支撑对RC框架造成的局部损伤，提高结构的功能可恢复性；该体系中的防屈曲支撑便于施工质量控制和现场组装，既可用于新建建筑，也可用于既有建筑的抗震加固。本项目综合采用实验与有限元数值模拟手段，考察该新型损伤控制结构体系的局部损伤特性、整体损伤分布、最大地震反应与残余位移反应等方面的抗震性能，重点研究其功能可恢复性，并建立相关设计建议。

以在整体结构中采用耗能减震子结构为特征的损伤控制技术是实现基于性能抗震设计和功能可恢复结构的经济有效途径。项目组提出一种新型的菱形布置屈曲约束支撑钢筋混凝土框架结构体系。该体系中的屈曲约束支撑对钢筋混凝土构件几乎不产生法向拉力作用，且连接节点远离钢筋混凝土框架梁端、柱端等预期塑性铰区，有助于减轻屈曲约束支撑对钢筋混凝土框架造成的局部损伤，提高结构的功能可恢复性；该体系中的屈曲约束支撑便于施工质量控制和现场组装，既可用于新建建筑，也可用于既有建筑的抗震加固。针对这一新型结构体系，项目组开展的主要工作和取得的主要成果包括：（1）通过一组6个屈曲约束支撑-混凝土连接节点的纯剪、拉剪-压剪往复加载试验，检验了包括栓钉、植筋和结构胶结等不同连接形式的可靠性，发现界面处一定的拉、压力对界面的破坏形态影响不大，现有的连接界面设计方法具有较高的可靠度，同时建立了连接节点的滞回模型；（2）建立了包含70个试件的屈曲约束支撑数据库，并进行了一组7个屈曲约束支撑轴心往复加载试验，提出了屈曲约束支撑超强系数上限值的经验公式，并发现了屈曲约束支撑的超强行为与加载速度之间具有相关性；（3）通过一组3个菱形布置屈曲约束支撑钢筋混凝土框架子结构的拟静力试验，检验了相邻屈曲约束支撑轴力的法向分量相互抵消的效果，试验结果表明，在这一新型布置形式下，屈曲约束支撑不会对周边混凝土构件的局部损伤特性造成不利的影响，有利于整体结构的损伤控制和震后快速恢复；（4）通过非线性动力时程分析，进一步验证了本项目提出的新型结构体系的有效性，同时揭示了非线性体系中高阶模态力可能对结构局部受力状态造成的显著影响，本项目提出的新型结构体系可最大限度的避免这一不利因素的影响。