低延性中心支撑钢框架结构抗倒塌能力储备与设计理论研究

The low-ductility steel concentrically braced frame is a kind of economical dual system. The brace system has low ductility, whereas the frame system which has a considerable reserve capacity after brace failure can resist the seismic loads. In China, the steel concentrically braced frames with different ductility capacity are not distinguished in seismic design procedures, resulting in uneconomical structural design, which restricts the development of low-ductility steel structures. The low-ductility steel concentrically braced frame has been widely used in the US moderate seismic region. However, the failure mechanism of this kind of structure is still unclear, and the seismic design theory is still not suitable..Regarding the problems above, this research will focus on evaluating seismic performance and developing a rational seismic design philosophy for low-ductility steel concentrically braced frame. Numerical simulation, experiment and theoretical study will be used to evaluate the structural failure mechanism, clarify the structural collapse ductility and seismic failure mechanism, and quantify collapse reserve capacity. Finally, the performance-based seismic design method for low-ductility steel structures will be established. Based on this research, the understanding for seismic performance of typical dual system will be promoted among civil engineers and designers. In addition, this research will provide scientific and theoretical basis for engineering construction and future implementation in relative standards.

低延性中心支撑钢框架结构是一种经济性优异的双重抗侧力体系。尽管支撑体系延性能力较低，但其失效后，结构剩余部分具有可观的能力储备，能够继续承担地震作用。对于延性能力不同的中心支撑钢框架结构，我国规范并未在设计方法上加以区分，导致结构设计不经济，制约了低延性钢结构的发展。该类结构在国外中、低抗震设防烈度地区得到了广泛应用，但结构灾变机理仍不明确，设计方法尚不完善。.针对上述问题，本项目将开展低延性中心支撑钢框架结构抗震性能与设计理论研究，通过试验研究、数值模拟和理论研究，阐明结构的失效机制，计算结构的倒塌延性，揭示该类结构的灾变机理，量化其抗倒塌能力储备，最终建立低延性钢结构性能化抗震设计方法。通过本项目的研究，将提高工程界对典型双重体系抗倒塌能力储备的认识，为指导该类结构的工程建设与制定相关设计规程提供科学依据。

针对低延性中心支撑钢框架结构（CBF）体系地震灾变机理不明确，抗倒塌设计方法不完善的问题，本项目对低延性中心支撑钢框架结构抗倒塌能力储备与设计理论展开研究。研究了地震作用下长耗能梁-偏心支撑机制对结构抗倒塌性能的影响，基于增量动力分析法，计算了低延性CBF结构在不同参数条件下的易损性，分析了储备承载力、储备刚度、结构周期、强度折减系数等设计参数对结构抗倒塌性能的影响，建立了低延性CBF结构的倒塌富裕度计算公式，提出了CBF结构抗倒塌性能简化评估方法，对CBF减震体系抗震性能进行了试验研究，建立了基于E-μ模型的CBF结构抗震性能提升设计方法，最后通过CBF加固设计与评估算例，验证了所提方法的适用性。研究成果发表学术论文7篇，其中SCI检索论文3篇。