周期温度作用下轴心受力混凝土结构徐变效应分析

Analysis of Creep Effect of Axially Stressed Concrete Structures Under Cyclic Temperature

为研究长期变温环境下考虑徐变效应时高速铁路纵连板式无砟轨道体系的结构内力,建立两端固定的轴心受力素混凝土板简化模型,设置假设条件,在已有的恒温徐变模型及变温徐变计算方法的基础上建立递推公式,分析温度参数和周期时间对徐变作用的影响,以及徐变对结构内力和变形的影响。结果表明:与不考虑徐变效应或考虑徐变系数恒定相比,考虑徐变系数随温度变化时结构受力更不利;预测结构整体内力变化趋势时,可不考虑日升降温对徐变效应的影响,只需考虑季节性升降温影响;长期受周期季节性温度变化作用,随周期温度作用循环次数的增加,结构最大拉应力增大,自第二循环起结构最大压应力减小。

In order to study the structural internal force of high speed railway longitudinal slab ballastless track system considering creep effect under long-term variable temperature environment,a simplified model of plain concrete slab with fixed ends under axial load was established.By setting assumptions,recursive formulas were established on the basis of the existing constant temperature creep model and variable temperature creep calculation methods,and the effects of temperature parameters and cycle time on the creep effect,as well as the effects of creep on the structural internal force and deformation were analyzed.The results show that compared to not considering the creep effect or considering the constant creep coefficient,considering the variation of creep coefficient with temperature is more unfavorable for the structural stress.When predicting the trend of overall internal force changes in the structure,the influence of daily temperature fluctuations on creep effect may not be considered,but only the seasonal temperature fluctuations need to be considered.Due to the long-term seasonal temperature changes,the maximum tensile stress of the structure increases with the increase of the number of cycles under the cyclic temperature effect,and the maximum compressive stress of the structure decreases from the second cycle.