新型自复位高强钢索支撑钢框架抗震机理及设计理论研究

Braced frames (BF) have been extensively applied in the seismic engineering field because of their high-efficiency in resisting lateral loads. However, conventional BF systems produce excessive permanent residual deformations after major earthquakes, which has severely adverse effects on the safety, economy and operating function of the structures. Therefore, the development of innovative braces with self-centering property has been at the center of the discussion and effort to control structural damage, reduce economic losses and maintain building function. This project proposal aims to conduct studies on the seismic mechanisms and design theory of the innovative self-centering tension braced (SCTB) steel frames with high strength steel cables: 1) Reveal the working mechanism of the SCTB through experiments and refined finite element simulations; propose control strategies on the first-order deformation and the second-order stiffness; develop design theory for the SCTB. 2) Construct an SCTB material object; investigate the seismic mechanisms of the SCTB steel frames theoretically and experimentally. 3) Propose cumulative hysteretic energy spectrum and its mathematical expressions for the equivalent nonlinear SDOF system of the SCTB steel frames under different performance objectives; determine the load pattern distributions along the structural height; reveal the mechanism and route of the plasticity induced in the beams and columns; propose the energy-based seismic design theory for the SCTB steel frames under different performance objectives. The research results are expected to provide theoretical basis for the engineering applications and also to offer thoughts for the innovations in the self-centering braces and their frame structures.

支撑框架是一类高效的抗侧力体系，在工程抗震领域得到了广泛应用。然而，传统的支撑框架在强震后往往会产生较大的塑性残余变形，对结构的安全性、经济性以及使用功能的连续性等方面造成极大的不利影响。因此，研发具有自复位功能的新型支撑对于控制结构损毁程度、降低震后经济损失、维持结构功能运转具有重要意义。本项目拟对新型自复位高强钢索支撑（SCTB）及其钢框架结构的抗震机理和设计理论开展深入研究：1)采用试验和精细有限元法揭示SCTB的工作机理，提出一阶刚度段变形和二阶刚度的定量控制方法；建立SCTB设计理论。2)开发SCTB新材料单元；通过试验和理论相结合研究结构抗震机理。3)建立不同目标性态下结构等效非线性SDOF系统的耗能需求谱及其数学表达；研究结构侧向加载模式，揭示梁柱塑性发展的机制和路径；发展基于能量的性态设计方法。研究成果可望为工程应用奠定理论基础，同时为自复位支撑及其结构体系的创新提供思路。

研发具有自复位功能的新型支撑对于控制结构震后损毁程度、降低震后经济损失、维持结构功能运转具有重要意义。本项目提出了一类新型柔性自复位支撑构件—基于预压碟簧的自复位拉索支撑（PS-SCCB），通过进行循环加卸载试验，验证了理论分析的正确性。采用有限元方法，进一步探讨了不同摩擦力和碟簧组预压力组合对PS-SCCB滞回性能的影响。提出了二阶刚度可控的PS-SCCB设计方法，并开发了支撑辅助设计软件。采用pushover方法研究了支撑关键参数对PS-SCCB钢框架结构推覆性能的影响。进行了考虑近、远断层距影响的时程分析，研究了PS-SCCB钢框架结构体系在多遇地震、设防地震和罕遇地震作用下动力响应。提出了面向PS-SCCB钢框架结构的三种性能等级以及基于位移的PS-SCCB钢框架结构抗震设计方法。研究成果可为该类新型支撑构件在实际工程中的应用提供理论参考。