无粘结预应力混凝土三跨连续板火灾试验研究

Experimental investigation of unbonded prestressed concrete continuous slab subjected to fire

在实现按照ISO标准升温曲线升温的前提下,研究了无粘结预应力混凝土连续板在火灾作用下的火灾行为。试验考察了预应力度、不同跨受火以及负筋长度三种因素,分析结果表明不同跨受火、负筋长度对三跨连续板的破坏机构、挠度变形有决定性的影响,而预应力度对其影响不是十分明显,三种因素都对支反力的重分布有很显著的影响,预应力筋中的预张力在火灾试验过程中经历了先增加,再减小,然后突然被拉断三个阶段,构件的温度场在受火面温度梯度大,背火面小,裂缝的出现和水蒸气的蒸发影响着板内温度场的分布。

Based on the ISO time-temperature curve, the behaviors of the unbonded prestressed concrete continuous slab （UPCCS） under fire are investigated. In the test, three important factors including degree of prestressing, different spans subjected to fire and the length of native reinforcing at the top of support are considered. The analysis of the test result firstly shows that different spans subjected to fire and the length of native reinforcing have decisive influence on the failure mode and deformation response of the component, while the degree of prestressing has little influnce. Secondly, it is also pointed out that all of factors have remarkable effect on the support reaction redistribution. Thirdly, it is concluded that the prestressing force experiences three stages with increase, decrease and rupture. Finally, the temperature fields distribution is presented to show that the temperature gradient is larger at the exposed fire side than the back side. The appearance of crack and evaporation of water contribute to the distribution of temperature fields.