预应力活性粉末混凝土梁抗火性能试验研究  

Experimental study on fire resistance of prestressed reactive powder concrete beams

作　　者：闫凯[1] 蔡浩 张耀[1] 张鑫[1] YAN Kai;CAI Hao;ZHANG Yao;ZHANG Xin(Key Lab of Building Structural Retrofitting and Underground Space Engineering of the Ministry of Education,Shandong Jianzhu University,Jinan 250101,China)

机构地区：[1]山东建筑大学建筑结构加固改造与地下空间工程教育部重点实验室,山东济南250101

出　　处：《建筑结构学报》2020年第9期105-115,共11页Journal of Building Structures

基　　金：国家自然科学基金项目(51878399,51408341);长江学者与教育部创新团队项目(IRT13075)。

摘　　要：活性粉末混凝土(RPC)是超高性能建筑材料,与高强预应力筋结合形成的预应力RPC梁具有显著的承载、变形和耐久性能优势,但预应力RPC梁的火灾安全性能是制约其广泛应用的关键问题之一。鉴于预应力RPC梁的火灾安全性亟待研究,以荷载水平、预应力筋保护层厚度、预应力筋类型、预应力度等为试验参数,设计制作了8个预应力RPC简支梁,开展了恒定荷载ISO 834标准升温条件下受火试验。获得了梁内温度变化、挠度-受火时间曲线、有效预应力、裂缝开展、爆裂分布及深度等试验数据,研究了火灾高温损伤演化规律和破坏模式。结果表明:干热养护可有效抑制RPC高温爆裂,受火试件保持了良好的完整性;荷载水平和预应力筋保护层厚度是影响预应力RPC梁抗火性能的关键因素,随荷载水平的减小和预应力筋保护层厚度的增大,耐火极限显著提高;荷载水平为0.5、预应力筋保护层厚度不小于45 mm可满足2.0 h的耐火极限要求;同等条件下有黏结预应力RPC梁的抗火性能优于无黏结预应力RPC梁;常温下按适筋梁设计的预应力RPC梁火灾下易发生少筋破坏。Reactive powder concrete(RPC)is a building material with super high performance.The prestressed RPC beams formed by the combination of RPC and high-strength tendons possess significant advantages in bearing capacity,deformation and durability.The fire safety of prestressed RPC beams is one of the key problems that limit its wide applications.To address the inadequacy in the understanding of the fire safety of prestressed RPC beams,this paper presented an experiment study involving a total of eight prestressed RPC beams,with the main test variables being the load level,RPC cover thickness,tendon type and PPR.The fire tests of the specimens under a constant load and the ISO 834 standard heating condition were carried out.The data including the temperature field,deformation,effective force of tendons,crack and fire-induced spalling of the specimens were obtained,and the damage process and failure mode were investigated.The test results show that the specimens maintain good integrity in fire tests,and that dry-heat curing can effectively suppress the spalling of RPC.The fire resistance of the specimens is influenced significantly by the load level and RPC cover thickness:the fire resistance of the prestressed RPC beams increases with the RPC cover thickness and decreases with the load level.The specimens with a load level of 0.5 and an RPC cover thickness of more than 45 mm can meet the fire resistance requirement of 2.0 h.Under the same conditions,the fire resistance of unbonded prestressed RPC beams is inferior to that of bonded prestressed RPC beams.The prestressed RPC beams designed to be under-reinforced at normal temperature are prone to failure as insufficiently-reinforced beams.

关 键 词：预应力梁 活性粉末混凝土 受火试验 高温爆裂 抗火性能 

分 类 号：TU378.2[建筑科学—结构工程] TU317.1