摘要
为了搞清火灾情况下无粘结预应力混凝土连续板的受力、变形、裂缝分布形式以及破坏机构等与常温下有什么不同,为对其进行抗火设计奠定基础.对3块12.6m×1.5m三跨连续板在边中两跨受火下的火灾行为进行试验研究,试验过程中采用ISO834标准升温曲线,并施加2.0kN/m2的使用荷载.试件主要考虑负弯矩筋长度的变化和预应力度.用位移传感器测量板的变形,用压力传感器测试支反力及预应力的变化情况.试验结果表明:裂缝形式主要有板顶斜裂缝、横向贯通裂缝以及沿预应力筋的纵向裂缝,未受火跨在试验过程中未发现任何肉眼可以观察到的现象.试验发现负弯矩筋长度决定了横向贯通裂缝出现的位置.预应力先增长后减少,最后预应力筋多被拉断.火灾情况下,无粘结预应力混凝土连续板的变形和内力重分布远比常温情况剧烈,裂缝分布形式以及破坏机构明显不同于常温,预应力损失严重.
To provide the basis for fire design of unbonded pretressed concrete slabs, differences of reactions, deformations, distributions of cracks, and failure modes of them under fire between those at normal temperature were studied. The fire behaviors of 3 unbonded prestressed concrete continuous slabs with three spans of 12.6 m length and 1.5 m width were studied. The specimens were exposed to ISO834 standardized heating regime and 2.0 kN/m2 load. Lengths of negative moment reinforcements and prestressing levels were considered as main factors as well. Deformations, reactions and prestresses of the slabs were obtained by different sensors. Test results show that distributions of cracks of spans under fire include the oblique cracks, the transverse through cracks and longitudinal cracks along the prestressing reinforcements of the top of slabs. No phenomena of span without fire during experiments can be observed by eyes. The lengths of negative moment reinforcements determine the locations of the transverse through cracks. The prestress increases firstly, and then decreases. Most of prestressed steels are broken at last. Large deformation and violent redistribution of internal force occur. Distributions of cracks and failure modes are different from those at normal temperature, and the prestress loses seriously.
出处
《哈尔滨工业大学学报》
EI
CAS
CSCD
北大核心
2009年第8期179-182,254,共5页
Journal of Harbin Institute of Technology
基金
国家自然科学基金资助项目(50178034)
国家自然科学基金重大国际合作研究项目(50320120156)
国家重点基础研究专项经费资助项目(2001CB409603)
关键词
火灾
连续板
负弯矩筋长度
预应力度
裂缝分布
fire
continuous slab
length of negative moment reinforcement
prestressing level
