四边简支现浇混凝土空心楼盖二次抗火性能试验研究

Experimental study on second fire-resistance performance of simply supported on four sides of cast-in-place concrete hollow floor

为探究火灾后采用聚合物砂浆加固修复混凝土空心楼盖二次火灾下的抗火性能,对四边简支混凝土组合塑料模盒空心楼盖进行两次火灾试验。介绍了试验空心楼盖第一次受火试验及火灾后构件修复情况,重点介绍了加固修复后空心楼盖第二次火灾试验,描述了试验空心楼盖在两次受火下的破坏特征、变形和温度场分布规律,并进行分析和对比。研究结果表明:采用聚合物砂浆修复的空心楼盖在二次火灾作用下,第一次火灾受损较为严重的部位易产生爆裂脱落,从而降低了耐火极限;二次受火下楼盖内混凝土的温度峰值高于一次受火,且距离板底越近,两次火灾作用中温度峰值差值越大;试件在两次火灾作用下跨中处最大竖向位移基本相同,第二次受火作用后的残余位移小于第一次;采用聚合物砂浆对火灾后的空心楼盖进行修复,修复后的楼盖仍具有一定的抗火性能。

In order to study the second fire-resistance performance of concrete hollow floor reinforced with polymer mortar, two anti-fire tests were carried out on composite concrete hollow floor with plastics boxes of four-sided simply supported. The first fire test of concrete hollow floor and the repair situation of concrete hollow floor after fire were introduced. The second fire test of the reinforced hollow floor was significantly introduced. The failure characteristics, deformation and temperature field distribution of the hollow floor under the two fire tests were described and compared. The results show that under the second fire, the parts of the hollow floor reinforced with polymer mortar which were badly damaged in the first fire are prone to burst and fall off, thus reducing the fire resistance limit. In the second fire, the temperature peak of concrete in the floor is higher than that of the first fire. The closer to the bottom of the floor, the larger the difference in temperature peak between the two fires. The maximum vertical displacement of the floor at the mid-span is almost the same under the two fires. The residual displacement after the second fire is less than that of the first fire. The hollow floor reinforced with polymer mortar after fire still has some fire-resistance performance.