冷拉时效后HRB400钢筋高温下力学性能试验研究

Experimental study on mechanical properties of aging cold-drawn HRB400 reinforcing bars at high temperatures

为揭示经历不同程度冷拉时效后钢筋的高温力学性能损伤规律,将其强度损伤规律与国内外相关试验结果以及现有规范中的高温下钢筋强度损伤模型进行比较。以经历不同程度冷拉时效后的HRB400钢筋进行高温下力学性能试验,获得冷拉时效后钢筋在20℃~700℃温度下的应力-应变曲线、屈服强度、极限强度及破坏形态。对冷拉时效后钢筋高温下的力学性能损伤退化规律进行分析和讨论,提出冷拉时效后HRB400钢筋高温下屈服强度和极限强度损伤模型。冷拉时效后HRB400级钢筋高温下力学性能与未经历冷拉钢材有较大区别,现有模型不能很好模拟经历冷拉时效后钢筋强度的变化规律。本文研究成果可为评估受损钢筋的高温下力学性能提供依据,为编制相关规范和工程应用提供参考。

In order to discover the variation of mechanical property of reinforcing bars with high temperatures due to different degree of damage by cold-drawing and aging,the measured strength reduction in the paper is compared with the relevant test results at home and abroad and the existing strength damage model for reinforcing bars adopted by codes and standards.A series of high temperature tests were conducted to experimentally study the mechanical behavior of HRB400 reinforcing bars after exposure to different degree of cold-drawn and aging effects.The stress-strain curves,yield strength and ultimate strength of cold-drawn and aging HRB400 reinforcing bars at 200℃~700℃were obtained.The mechanical properties of cold-drawn and aging reinforcing bars at high temperature were analyzed and discussed,and the yield strength and ultimate strength damage model of cold-drawn aging HRB400 reinforcing bar at high temperature was put forward.The mechanical properties of cold-drawn aging HRB400 reinforcing bars at high temperatures are quite different from those of reinforcing bars that have not undergone cold-drawing.The existing models cannot well simulate the changing law of their strength.The research in the paper can be used to evaluate the mechanical properties of damaged reinforcing bars at high temperature and provide reference for the preparation of relevant codes and engineering applications.