考虑先后浇混凝土时变作用的装配式钢混组合梁长期效应分析

Analysis of long-term effects of prefabricated steel-concrete composite beams considering the time-varing effects of pre-cast concrete and post-cast concrete

为了研究先、后浇混凝土不同步时变效应对装配式钢-混组合梁的影响,基于混凝土收缩徐变规律和装配式栓钉群非均匀滑移变形,建立了装配组合梁的精细化长期时变效应有限元模型;与典型试验对比后验证了该数值模型的可靠性,分析了长期时变效应下钢梁、混凝土和栓钉的力学行为,探讨了影响装配式组合梁长期效应的主要因素。结果表明:采用时变刚度徐变函数和时变温度收缩函数的数值模拟方法,可以较好地用于装配式组合结构时变效应分析中;装配式组合梁的时变效应可以分为快速增长期(0~360 d)、慢速增长期(360~1 800 d)、平稳增长期(1 800 d后)3个阶段,在5年后基本稳定;考虑时变效应后,装配组合梁跨中长期挠度达到短期挠度的1.73倍,栓钉长期应力为短期应力的3.11倍;加载龄期、存梁时间和环境相对湿度是影响装配式组合梁长期挠度的重要因素。

In order to study the effect of the asynchronous time-varying effect of precast and post-cast concrete on prefabricated steel-composite beams,a fine long-term time-varying effect finite element model of prefabricated steel-composite beams was established based on the shrinkage and creep law of concrete and the non-uniform sliding deformation of prefabricated bolts.Compared with typical tests,the reliability of the numerical model is verified,the mechanical behaviors of steel beams,concrete and studs under long-term time-varying effects are analyzed,and the main factors affecting long-term effects of prefabricated composite beams are discussed.The results show that the numerical simulation method of time-varying stiffness creep function and time-varying temperature shrinkage function can be used to analyze the time-varying effects of prefabricated composite structures considering the long-term effects of concrete before and after pouring.The time-varying effect of prefabricated composite beams can be divided into three stages,rapid growth period(0~360 d),slow growth period(360~18 00 d),and steady growth period(after 1 800 d),which are basically stable after 5 years.Considering the time-varying effect,the long-term deflection of the mid-span of the assembled composite beam is 1.73 times of the short-term deflection,and the long-term stress of the stud is 3.11 times of the short-term stress.Loading age,beam storage time and relative humidity are important factors affecting the long-term deflection of assembled composite beams.