【摘要】 鉴于预应力钢丝高温下及高温后的力学性能是开展预应力结构抗火设计及进行火灾后预应力结构损伤评估与修复的重要依据,对16个1770级P5低松弛预应力钢丝试件进行了高温下拉伸试验,14个钢丝试件进行了高温后拉伸试验。试验表明,随着温度升高,高温下钢丝应力-应变关系曲线形状趋于平缓,钢丝的强度、弹性模量等力学指标不断退化;对于高温后钢丝,温度历程低于300℃时,钢丝力学性能变化不明显;高于300℃时,随温度历程的升高,钢丝应力-应变关系曲线逐渐软化,钢丝各项力学指标逐渐退化。应用粘弹性力学理论,得到了去除加载速率影响的高温下钢丝应力-应变关系曲线,得到了钢丝各项力学指标在高温下及高温后的退化规律,建立了高温下及高温后的钢丝应力-应变曲线方程。为开展预应力结构抗火性能分析及火灾后损伤评估提供了基础性素材。更多还原

【Abstract】 The mechanical properties of prestressing steel wire at and after high temperature are the key factor in design of fire resistance and after-fire damage evaluation of prestressed structures.A tensile experiment of 16 prestressing steel wires(fptk= 1770N/mm2,d=5mm,low relaxation of stress) at high temperature and a tensile experiment of 14 prestressing steel wires after high temperature were carried out.According to the experiment,the shapes of stress-strain curves of steel wire at high temperature become smooth and the mechanical property indexes of the steel wire such as strength,modulus of elasticity,etc.degenerate continuously as temperature increase.According to the experiment after high temperature,the mechanical property of steel wire varies little when the highest temperature that the steel wire reaches is less than 300℃;while the stress-strain curves of steel wire become more ductile and the mechanical property indexes of the steel wire degenerate gradually when the highest temperature is more than 300℃.By applying the theory of viscoelastic mechanics,stress-strain curves of steel wire at high temperature without loading speed influence are obtained.Laws of mechanical property indexes of the wire at high temperature and after high temperature are presented.The mathematic models of the stress-strain relationship of the prestressing steel wire at and after high temperature are established.All can be served as basic data for analysis of fire resistance and after-fire damage evaluation of prestressed structures.更多还原