高温对HSC造成损伤的动态分析

Compressive dynamic damage of high-strength concrete after elevated temperatures

对60个高强混凝土(HSC)棱柱体进行高温加热,温度分别为20、200、400、600、800℃。对棱柱体进行高温后轴向动态受压试验,应变率分别为10-5、10^(-4)、10^(-3)、10^(-2) s^(-1)。基于棱柱体的动态受压性能,研究了高温和轴向应变对HSC动态损伤演化规律的影响。结果表明,随着温度升高,HSC将会出现裂缝,细观结构变得松散;应变率对高温后HSC的损伤没有明显影响;经历相同的高温损伤后,HSC的相对受压强度随应变率的增大而增大;轴向应变对高温后HSC造成的损伤在峰值应变前缓慢增大,达到峰值应变后迅速增大;温度越高,峰值应变对应的HSC损伤越小,而经历相同温度后不同应变率下峰值应变处HSC损伤的变化趋势不明显。建立了HSC高温损伤以及高温损伤后相对受压强度的计算公式。

Sixty prisms of high-strength concrete （HSC） were heated, and the exposed temperatures were respectively 20, 200, 400, 600 and 800 ℃. Then the uniaxial dynamic compres- sive tests of prisms were conducted at strain rates of 10-5, 10-4, 10-3 and 10-2 s-1. Based on the dynamic compressive behavior of the prism, the effects of elevated temperatures and axial strains on the dynamic damage evolution of HSC were studied. The results showed that cracks will appear in HSC and the meso-structure of HSC becomes loose as the elevated tem- perature increases; the strain rate has no obvious influence on the elevated temperature damage of HSC ; the relative compres- sive strength of HSC after the same elevated temperature dam- age increases with the increase of the strain rate; the damage of HSC after elevated temperatures caused by the axial strain ap- pears to be a slow and quick increase before and after the peak strain, respectively; the higher the elevated temperature is, the smaller the damage of HSC corresponding to the peak strain be- comes, yet the change tendency of the HSC damage after expo- sure to the same elevated temperature at different strain rates is not obvious. The equations for the elevated temperature damage and the relative compressive strength after elevated temperature damage of HSC are established.