高温消防喷水冷却后混凝土应力-应变本构方程及剩余强度评估

Stress-strain Constitutive Relation and Residual Strength Evaluation of Concrete After Being Subjected to High Temperatures and Spray Cooling

为了更深入地揭示高温消防喷水冷却后骨料差异对混凝土轴压性能的影响,制作了普通混凝土、高强混凝土、再生混凝土标准棱柱体试件,进行不同高温喷水冷却后的单轴压缩试验,获取了试件的应力-应变全曲线方程,对比分析了高温喷水冷却对3种混凝土试件的峰值应力、峰值应变、弹性模量等力学性能指标的影响规律差异及损伤过程。结果表明:高温喷水冷却后高强混凝土表面裂缝发展较早且较快;温度升高时,再生混凝土应力-应变曲线峰值点右移最明显,高强混凝土曲线峰值点降低最小;随着温度的升高,普通混凝土的峰值应力下降最明显,再生混凝土的峰值应变上升较大;高温喷水冷却后高强混凝土弹性模量下降最少;随着温度的升高,再生混凝土的损伤发展差异最显著且耗能量下降最少。基于试验数据,提出了不同高温喷水冷却后的不同类型混凝土单轴应力-应变本构方程及剩余强度评估计算式,其拟合效果较好。

In order to further reveal the influence of aggregate type on the performance of concrete under axial compression after being subjected to high temperatures and spray cooling,uniaxial compressive strength tests of concrete after being subjected to different fire temperatures and spray cooling were carried out on standard prismatic specimens of ordinary concrete,high-strength concrete,and recycled aggregate concrete.The stress-strain curves during the whole axial compression process were obtained.The effects on the peak stress,peak strain,elastic modulus of three kinds of concrete specimens and their damage process after being subjected to high temperatures and spray cooling were compared and analyzed.The test results showed that:after being subjected to high temperatures and spray cooling,the cracks of high strength concrete surface developed earlier and faster;the peak point of recycled aggregate concrete curve moved to the right most obviously as temperature increased,and the peak point of high strength concrete curve decreased the least;with the increase of temperature,the peak stress of ordinary concrete decreased most obviously,the peak strain of recycled aggregate concrete increased the most;the elastic modulus of high-strength concrete decreased least after being subjected to high temperatures and spray cooling.With the increase of temperature,the difference of damage development of recycled aggregate concrete was the most significant,while the energy consumption was the lowest.Based on the test results,the strength evaluation formulas and uniaxial stress-strain constitutive equation of different concrete after being subjected to different fire temperatures and spray cooling were put forward,and the calculated values were in good agreement with the actual values.