再生混凝土筒体耐火性能试验研究与理论分析

Experimental study and theoretical analysis on fire resistant performance of recycled concrete tubular structures

为研究再生混凝土筒体的耐火性能,进行了3个混凝土筒体试件高温下工作性能试验研究。3个试件分别为普通混凝土筒体,粗骨料为再生骨料、细骨料为天然骨料的半再生混凝土筒体,粗骨料、细骨料均为再生骨料的全再生混凝土筒体。分析3个试件的温度场、竖向位移、墙体挠度及耐火极限。利用ABAQUS软件,模拟分析了筒体混凝土温度场,分析结果与试验结果符合较好。研究表明:随着再生骨料取代率的增加,混凝土内部温度的增加速率减小;相同受力和受火条件下,同一位置再生混凝土比普通混凝土的温度低;由于再生混凝土孔隙率略大,在荷载和高温共同作用下,其受力性能比普通混凝土略差;随再生骨料取代率的增加,耐火极限逐渐降低。

In order to study the fire resistant performance of recycled concrete, three concrete tubular structure specimens were designed and tested under high temperature. One of the specimens was made from normal concrete, one from half recycled concrete with recycled coarse aggregate and natural fine aggregate, and one from full recycled concrete with recycled coarse and recycled fine aggregate. The temperature field, vertical displacement, wall deflection and fire endurance were comparatively analyzed. The concrete temperature field of the specimens was simulated by ABAQUS software and the FEM results agreed well with the experimental results. Results show that the rate of temperature increasing inside the concrete becomes slower with the increase of recycled aggregate replacement rate. At the same position, the temperature of specimens with recycled concrete is lower than that with normal concrete at the same loading condition and same fire condition. However, the load carrying capacity of specimens with recycled concrete is lower than that of the normal concrete specimen due to the larger porosity of recycled concrete. The fire endurance decreases with the increase of recycled aggregate replacement rate in the specimens.