预应力混凝土连续板不同跨受火火灾行为

Behaviours of unbonded prestressed continuous concrete slabs with middle span and edge span subjected to fire in-order

为了研究三跨连续板不同跨依次受火作用下的火灾行为,对4块尺寸为12.6m×1.5m×0.12m的无粘结预应力砼连续板进行了火灾试验.试验考虑了连续板中跨和边跨在不同时间段发生火灾及负弯矩区负筋长度两种因素,在实现ISO标准升温的前提下,给出了板中水在火灾中全过程变化现象以及板在火灾作用下裂缝发生、扩展及最终形式,重点研究了板的变形、破坏机构的形成、预应力筋中拉力的变化,板中温度场以及支座支反力的重分布情况.通过对试验结果的分析,揭示了破坏机构形成和支反力重分布的原因,指出了板中温度场的分布情况及预应力筋拉力的变化特征.

To study the behaviours of unbonded prestressed continuous concrete slabs with middle span andedge span subjected to fire in-order, four unbonded prestressed concrete continuous slabs with the size of 12.6m × 1.5m ×0. 12m have been tested. Two important factors were taken into accout in the test. One was middle span and edge span subjected to fire in-order, the other was the length of nagative reinforcing bar existing in the zone of negative moment at the middle support. Based on the premise that the ISO time-temperature curve would achieve, the whole variety processs of water in slab and the slab cracking during the course of fire test were presented. The investigation was carried out with the emphasis on the deformation of slab, the formation of failure framework, the variety of prestressing in prstressing strand, the temperature fields in slab and the redistribution of support force. By the analysis of the results, the reasons of the formation of destruction framework and the redistribution of support force were found. The distribution of temperature fields of slabs and the variable regularity of prestressing were also given.