Q345B钢在大应变下的循环加载试验研究.doc

  Q345B 钢在大应变下的循环加载试验研究# 吴旗1，陈以一2，周锋1** （1. 同济大学土木工程学院，上海 200092； 5 10 15 20 25 30 35 40 2. 同济大学土木工程防灾国家重点实验室，上海 200092） 摘要：本文对 Q345B 钢材在循环往复加载下的滞回性能进行了试验研究，考虑了循环拉伸、 等幅升幅、等幅降幅和等幅交替四种不同的循环加载制度，最大循环应变幅达到了±10%。 为了避免在试验过程中出现失稳现象，本文采用较小标距直径比的循环加载试件。首先通过 循环加载试件有限元分析及标准试件与非标准试件的单调拉伸试验结果对比，论述了循环加 载应力应变曲线以真实应力应变表达的有效性。然后对循环加载试验现象进行了分析，对比 了 Q345B 钢材循环加载曲线和骨架曲线，评价了 Q345B 钢材在大应变下的滞回性能。 关键词：结构工程；钢结构；大应变；循环加载；滞回性能 中图分类号：TU391 Cyclic loading tests of Q345B under large inelastic strains WU Qi1, CHEN Yiyi2, ZHOU Feng1 (1. Civil Engineering School, Tongji University, Shanghai 200092; 2. State Key Laboratory of Disaster Reduciton in Civil Engineering, Tongji University, Shanghai 200092) Abstract: Cyclic loading experiments on Q345B structural steel were conducted to well understand the hysteretic behavior under large inelastic strains. A total of 4 different loading protocols were considered, with maximum strain amplitude up to ±10%. The short gauge length-to-diameter ratio was used for the cyclic loading coupon specimens, such that the buckling of the specimens was avoided. The strain uniformity within the gauge length of cyclic loading coupon specimens has been verified by finite element analysis. Further, the validity of the hysteretic stress-strain curve in expression of true stress and true strain has been proved by comparing the monotonic true stress-strain curve of cyclic loading coupon specimen with short gauge length-to-diameter ratio to that of standard coupon specimen with gauge length-to-diameter ratio of 5.4. The stress-strain curves of cyclic loadings were plotted and the experimental phenomena of specimens’ fractures were discussed. The hysteretic behavior of Q345B steel was evaluated based on the test results. Key words: structure engineering; steel structural; large inelastic strains; cyclic loading; hysteretic behavior 0 引言 我国地震活动频繁，地震作用是结构设计和分析计算中需要考虑的重要因素，而钢材在 循环往复作用下的响应是研究钢结构抗震性能的基础[1]。?在强地震作用下，钢结构会经历较 大的塑性变形，构件可能因为塑性变形过大而断裂，进而导致整个结构在强地震作用下有破 坏的危险[2]。这就需要研究钢材