考虑截面应力重分布的钢筋混凝土柱徐变分析

Creep behavior of reinforced concrete column in consideration of sectional stress redistribution

为研究考虑截面应力重分布对轴压柱混凝土徐变的影响,完成了12组24个几何尺寸为100 mm×100 mm×400 mm的素混凝土试件在不同应力水平下的徐变试验。运用MATLAB编写的程序,分析了关键参数对钢筋混凝土柱徐变的影响。结果表明：当初始压应力水平不大于0.35时,徐变过程中卸载回弹应变系数为0.89;当初始压应力水平高于0.35时,随初始压应力水平的增大,卸载回弹应变系数减小。随加载龄期的延长、纵向受压钢筋配筋率的增大、截面尺寸的增大、混凝土强度的降低、初始压应力水平的减小、环境温度的降低、环境相对湿度的增大,轴心受压钢筋混凝土柱徐变值减小。基于模拟分析结果拟合得到了C20~C50轴压钢筋混凝土柱徐变终值与各关键参数的关系式。

In order to investigate the effect of sectional stress redistribution on creep behavior of axial compressive concrete column,creep experiments were conducted on 12 groups of 100 mm × 100 mm × 400 mm concrete specimens under variable compressive stress. The effect of key parameters on the creep of reinforced concrete column and the sectional stress redistribution was investigated using the program edited by the MATLAB software. The results show that the spring-back strain coefficient is 0. 89 when the initial stress level is not larger than 0. 35,and the initial stress level decreases with the increase of the initial stress level after the initial stress level is higher than 0. 35. The ultimate creep value of axial compression reinforced concrete column decreases with the prolongation of the load age,the increase of longitudinal compression steel reinforcement ratio,section size and relative humidity,the decrease of concrete strength,initial stress level and temperature. The relations between the stable ultimate creep value of axial compression reinforced C20 ~ C50 concrete column and each key parameters were fitted based on the simulation results.