钢管混凝土拱的时变动力跳跃屈曲

Time-dependent dynamic snap buckling of concrete filled steel tubular arches

受到核心混凝土收缩徐变的影响,钢管混凝土拱将产生随时间变化的屈曲前变形和内力重分布,导致其动力跳跃屈曲荷载随时间变化而变化。针对钢管混凝土拱在阶跃荷载下的时变动力跳跃屈曲问题,采用能量法和基于龄期调整的有效模量法建立了钢管混凝土拱在阶跃荷载下的运动方程,然后通过能量守恒定律求得具有时变效应的钢管混凝土拱动力跳跃屈曲荷载,并与有限元结果进行对比验证。数值分析结果表明,核心混凝土的收缩徐变显著降低了钢管混凝土拱的动力跳跃屈曲荷载,当持载龄期达到300d时动力跳跃屈曲荷载降低约27.9%。

A time-dependent prebuckling deformation and internal force redistribution of concrete filled steel tubular(CFST)arches are resulted from the shrinkage and creep of the concrete core,which will lead to a time-dependent dynamic snap buckling load of the CFST arch under a step point load.Theoretical analysis for the time-dependent dynamic snap buckling load of CFST arches under a step point load was presented.The equation of motion for the CFST arch under a step point load was established by using the energy method and the age-adjusted effective modulus method,then its timedependent dynamic snap buckling load was further derived by using the principle of energy conservation,which was compared to the finite element results.Numerical results show that the decrease of dynamic snap buckling load of CFST arches is as a result of the shrinkage and creep of the concrete core.When the loading age is up to 300 days,the decrease of dynamic snap buckling load is about 27.9%.