地震作用下高强钢框架受力性能和抗震性能化设计方法研究

High strength steel structures have been applied in many projects all over the world with excellent social and economic benefits. The material properties of high and ultra-high strength steel are much different from traditional steel, e.g. yield plateau, hardening and deterioration, significant nonlinearity, etc, which will influence and change the behavior and safety of steel frames under earthquakes. But currently there hasn't been any research on the seismic behavior of high and ultra-high strength steel frames. Based on the high strength steel properties, this project will change the traditional seismic design theory which use only ductility to resist earthquakes, and will propose an innovative seismic design theory which consider both over-strength loading capacity and deformation capacity. This project will deeply investigate the behavior of high and ultra-high strength steel frames under earthquakes, carry out horizontal cyclic loading experiments on full-scale high strength steel frame specimens, then develop finite element models to simulate accurately the influence of high strength steel properties and constitutive model and the plate width-to-thickness ratio on the behavior of frames under earthquakes to achieve the quantitative relationship. Based on the research, an innovative performance-based seismic design theory and calculation method, which can make full use of the advantages of high strength steel and is applicable to high strength steel frames, will be proposed, and the corresponding formulae will be put forward. This research topic is based on the long-term research work of the applicant on high strength steel structures, and is of high scientific value and innovation. This research will improve current steel structure seismic design method and ensure the safety of steel structures, promote the application of high strength steel structures in our country, and be helpful to develop low-carbon economics and protect the environment.

高强钢结构已在国内外多个工程中取得成功实践。高强和超高强钢材的材性与传统钢材相比有较大变化，包括是否有屈服平台、强化和退化性能、强非线性等，极大地影响钢框架受力性能，但关于其抗震性能的研究还很少。本项目基于高强钢材的基本性能，改变传统的单一依靠延性的抗震思路，采用综合考虑承载力超强和变形能力的性能化抗震理论，深入研究地震作用下高强和超高强钢框架的受力性能，发展可准确模拟高强钢材本构关系以及板件屈曲等因素的数值模型，结合高强钢框架足尺试件的循环加载试验，全面研究高强钢材力学性能以及板件宽厚比对其抗震性能的影响，建立能够发挥高强钢优势、适用于高强钢框架的抗震性能化设计理论、计算方法，给出验算公式。本项目基于申请人长期从事高强钢结构研究工作，具有重要科学价值和创新性，对于完善钢结构抗震设计理论、保证安全性、促进高强钢结构的应用、保护环境以及发展低碳经济目标的实现，都具有前瞻性理论意义和应用价值。

高强钢材力学性能与普通钢材具有显著区别，对钢框架抗震性能具有重要影响。本项目对高强钢框架抗震性能及设计方法展开研究，取得的主要研究成果如下：.(1) 开发了结构钢材全过程弹塑性本构模型。通过材性试验研究了Q550和Q690两种高强钢材的单调和滞回性能。分别提出了有屈服平台和无屈服平台结构钢材的循环弹塑性本构模型，探讨了基于单拉应力－应变曲线和经验关系标定其材料参数的方法，并在通用有限元程序ABAQUS中成功实现，应用于钢结构材料、构件和节点的非线性分析，充分验证了其精度和数值稳定性。.(2) 完成了高强钢框架抗震性能的足尺试验。对按我国《钢结构设计标准》设计的共6个单跨两层钢框架足尺试件进行了循环加载试验，分析了其破坏形态、承载力、变形、延性和耗能能力，探讨了梁柱构件和盖板加强型梁柱节点的受力性能。结果表明采用延性较好的节点构造和截面类型后，高强钢框架的滞回性能稳定，表现出良好的变形和耗能能力，各个试件亦均满足规范大震下的不倒塌性能要求。.(3) 建立了高强钢框架抗震分析的数值模型。以可考虑构件局部屈曲和梁柱节点变形的精细壳单元有限元模型为工具，利用开发的结构钢材循环弹塑性本构模型，对高强钢框架足尺试验进行了模拟和预测。结果表明建立的数值模型能够准确地描述框架整体和节点局部的滞回曲线以及柱脚屈曲形态，并验证了梁－壳高效多尺度模型的可靠性。.(4) 进行了高强钢框架抗震性能的参数分析并提出了设计建议。建立了三跨六层高强钢和混合钢框架算例的高效多尺度模型，通过静力推覆和动力时程分析研究了钢材等级、截面宽厚比对承载力和变形需求的影响，分析了基于首次屈服承载力的地震力折减系数，结果表明高强钢框架能满足大震不倒的性能要求，并对其建议了最小性能系数和节点转动需求。