拉索防火涂层对预应力组合梁抗火性能的影响  

The Influence of Fireproof Coating on Cable to the Fire Resistance of Prestressed Composite Beams

作　　者：周焕廷[1] 张苏鹏 郑志远 秦晗 伍先兴 陈志华[1] ZHOU Huanting;ZHANG Supeng;ZHENG Zhiyuan;QIN Han;WU Xianxing;CHEN Zhihua(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430070,China)

机构地区：[1]武汉理工大学土木工程与建筑学院,武汉430070

出　　处：《建筑钢结构进展》2021年第5期29-36,72,共9页Progress in Steel Building Structures

基　　金：国家自然科学基金(51878528);中央高校基本科研业务费资助项目(195206003)。

摘　　要：采用有限元软件ABAQUS建立了用于模拟预应力组合梁在火灾下全过程受力行为的模型,研究拉索防火涂层对预应力连续组合梁抗火性能的影响。考察组合梁跨中挠度、拉索应力及塑性应变随温度的变化,分析了预应力组合梁在高温下的温度变化和破坏模式。结果表明:钢梁下翼缘与腹板升温较快,二者温差很小,而腹板与上翼缘的温差较大;混凝土截面各测点处升温速率由下至上依次降低,上表面与下表面的最高温度差可达约700℃;当拉索有5 mm厚防火涂层时,在升温前期其温度随时间延长而上升的幅度比无防火层时温度上升的幅度要小,同一升温时间下,二者温度差值最大可达175℃;而当升温时间达到13 min时,二者温差开始减小,直至升温时间为60 min时,其温度曲线基本重合;预应力连续组合梁在高温下的破坏形态主要以跨中挠度变形过大为主,中间支座处腹板与下翼缘发生对称弯曲变形;防火涂层延缓了拉索的温度上升,在同一荷载和温度下拉索能够承担的应力更大,对组合梁的抗弯贡献也更大。A model for simulating the behavior of prestressed composite beams under fire was built by using finite element software ABAQUS.The influence of fireproof coating on cable to the fire resistance of prestressed continuous composite beams was studied.The variations of mid-span deflection, cable stress and plastic strain of the composite beam with changing temperatures were investigated.The temperature change and failure mode of prestressed composite beams at high temperature were analyzed.The results indicate that the lower flange and web of the steel beam are heated faster, the temperature difference between these two is small, and the temperature difference between the web and the upper flange is larger.The heating rate at each measuring point of the concrete section decreases from bottom to top, and the maximum temperature difference between the lower surface and the upper surface can reach about 700 ℃.When the cable has a 5 mm thick fireproof coating, the temperature rises with time in the early stage of temperature rise and is slower than that without the fireproof coating, and the maximum temperature difference value can reach up to 175 ℃ under the same heating up time.When the heating up time reaches 13 min, the temperature difference begins to decrease.The temperature curve coincides until 60 min.The failure mode of the prestressed continuous composite beam at high temperature is mainly excessively deformed by the mid-span deflection.The web at the middle support and the lower flange have symmetrical bending and buckling deformation.The fireproof coating delays temperature rise of the cable, and the stress can be assumed by the pulling cable at the same load and temperature.It also contributes more to the bending moment capacity of composite beams.

关 键 词：预应力连续组合梁 抗火性能 有限元法 预应力拉索 防火涂层 破坏形态 

分 类 号：TU331.1[建筑科学—结构工程]