高温后高强混凝土受压动态损伤

对45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℃和800℃。然后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 s^-1、10^-3 s^-1和0.067 s^-1。结果表明：随着经历温度的升高，HSC将会出现裂缝，细观结构变得松散；高温对HSC造成的损伤随温度的升高而增大，而应变率对高温后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损伤的变化趋势并不明显。基于试验及理论分析，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。

COMPRESSIVE DYNAMIC DAMAGE OF HIGH-STRENGTH CONCRETE AFTER ELEVATED TEMPERATURES

Forty-five high-strength concrete (HSC) prisms were heated, and the exposed temperatures were respectively 20℃, 200℃, 400℃, 600℃ and 800℃. Then the uniaxial dynamic compressive tests of prisms were conducted at strain rates of 10-5 s-1, 10-3 s-1 and 0.067 s-1. The results show that cracks will appear in HSC and that the meso-structure of HSC becomes loose as the elevated temperature increases. The HSC damage caused by the elevated temperature increases with the increasing exposed temperature, yet the strain rate has no obvious influence on the elevated temperature damage of HSC. The relative compressive strength of HSC after the same elevated temperature damage increases with the increase of its strain rate. The HSC damage after elevated temperatures caused by the axial strain appears to be a slow and a quick increase before and after the peak strain, respectively. The higher the elevated temperature is, the smaller the HSC damage corresponding to the peak strain becomes, yet the change tendency of the HSC damage after exposure 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 based on experimental and theoretical analyses.