双向压弯薄柔H形截面钢构件的滞回性能

Safety of structural members under multi-direction seismic actions has been one of the critical issues in structural design. With the potential trend towards the employment of slender steel members (members that could not satisfy the requirements for plastic sections) even in areas where earthquake occurs frequently, it is necessary to investigate the seismic behavior of such members under biaxial horizontal seismic actions. In this project, the inelastic behavior of H-sectional slender steel members used for light-weighted steel structures under combined compression and biaxial bending will be thoroughly investigated through experimental, numerical and theoretical studies. Firstly, the basic properties of the members under biaxial loading, such as the failure mechanism, interaction behavior of biaxial moments as well as plate buckling interaction effects will be investigated, where the dominating parameters can be determined. Secondly, the interactive curves of biaxial ultimate strength based on the uniaxial ultimate strength and the spatial hysteretic model, both incorporating the influence of plate interaction and local buckling, will be proposed. Lastly, evaluation approaches for energy dissipation mechanism of slender members under spatial loading condition will be presented, and then seismic design suggestions regarding combined effects of strength-ductility-energy dissipation will be given. This project will improve the application efficiency of slender members in steel building structures and make a contribution to residential building industrialization and urbanization development.

构件在多维地震作用下的安全性始终是结构设计的基本问题之一，为推广薄柔截面钢构件(不满足塑性截面要求的板件组成的构件)的应用并确保其在地震作用下的安全性，亟需对其在双向水平地震作用下抗震性能展开研究。本项目以轻量化钢结构中的薄柔H形截面钢构件为主要研究对象，采用试验研究、非线性有限元数值分析和理论研究相结合的研究方法，系统研究其在轴力和双向弯矩共同作用下的滞回性能。本项目将深入揭示薄柔截面钢构件在双向压弯作用下的破坏机理、双向弯矩相互作用及板件屈曲相关作用等基本规律，确定影响构件性能的主要因素；解决考虑板件相关作用及局部屈曲影响的极限承载力相关曲线计算方法与空间恢复力模型等基本问题；建立钢构件空间受力条件下的屈曲耗能评价机制；提出承载、延性与耗能三者综合控制的抗震设计建议。本项目将有效提高薄柔截面钢构件在建筑钢结构中的应用效率，为加速我国住宅产业化发展及城镇化建设做出贡献。

本项目对薄柔H形截面钢构件在双向压弯作用下的滞回性能展开了系统研究。首先对薄柔H形截面钢构件进行了常轴压力下往复双向压弯的试验研究；随后采用大型有限元软件ABAQUS展开了参数分析；基于试验和参数分析，对薄柔截面钢构件在轴力和双向弯矩共同作用下若干基本问题进行了深入分析。.研发并加工了一套精密的三维加载测量试验系统，对18根不同宽厚比及加载路径下的H形截面钢构件进行了常轴压力下双向压弯滞回性能试验，考察了在复杂加载路径下以局部屈曲为主要破坏机制的钢结构构件的破坏机理，极限承载能力、延性、耗能能力等重要性能。.采用ABAQUS软件建立了能精确考虑各项非线性性能的有限元模型，并用该模型进行了大量的参数分析。考察了其中最主要的影响参数，包括翼缘宽厚比、腹板宽厚比、轴压比及加载方向角等，对薄柔H形截面钢构件双向压弯性能的影响机理。.归纳总结出4种主要破坏模态，包括全截面塑性、翼缘屈曲先于腹板屈曲、腹板屈曲先于翼缘屈曲、和翼缘腹板同时屈曲。并探讨了这4种破坏模态的全程应力发展过程、双向弯矩-转角发展过程及极限状态的特点。该发现从微观机制上解释了H形截面钢构件双向压弯下的板件屈曲相关机理，及其对构件承载性能的影响机制。.提出“能量拐点法”确定了双向压弯下的极限状态。其核心观点是将能量视为加载位移的曲线，外力做功的零交叉点时刻视为承载力的峰值点。并基于大量参数分析，提出了操作简单，概念清晰的双向压弯极限曲线。该曲线可为H形截面钢构件复杂受力状态提供设计依据。基于试验和大量参数分析得到的弯矩-曲率关系提出了基于骨架曲线（边界曲线）和滞回规则的恢复力模型，该恢复力模型含有板件屈曲相关作用的影响。.构件在多维地震作用下的安全性始终是结构设计的基本问题之一，本项目研究将有效提高薄柔截面钢构件在装配化建筑钢结构中的应用效率，同时为各种轻量化的钢结构提供思路。