火灾下预应力混凝土箱梁抗弯承载力衰变研究  

Flexural Capacity of Prestressed Concrete Box Girder Exposed to Fire

作　　者：张岗[1] 程海鲲 王翠娟[2] 刘天龙[1] 

机构地区：[1]长安大学公路学院,西安710064 [2]长安大学工程机械学院,西安710064

出　　处：《武汉理工大学学报》2015年第4期71-76,共6页Journal of Wuhan University of Technology

基　　金：国家自然科学基金(51308056);中央高校基本科研业务专项资金资助项目(2014G2210003);国家留学基金(201406565013)

摘　　要：采用温度-力耦合的火灾全程数值模拟方法,设定了火灾场景,基于强度损失的虚拟层截面等效计算,分析了预应力混凝土箱梁正截面抗弯承载力随火温时间的变化规律,给出了预应力混凝土箱梁正截面抗弯承载力与火灾高温之间的时程变化关系。结果表明,随火温时间的持续,预应力混凝土箱梁正截面抗弯承载力呈二次抛物线下降;由跨中至端部的正截面抗弯承载力衰减幅度逐渐增大;箱内受火时的正截面抗弯承载力损失值大于箱外受火时的正截面抗弯承载力损失值;拟合提出了不同火灾场景下预应力混凝土箱梁正截面抗弯承载力的时程衰变计算公式,公式简洁,可为桥梁抗火设计及灾后评价提供依据。Utilizing the thermo-mechanical coupled method of fire process and setting the fire scenario, based on the e- quivalent calculation of cross sectional virtual layer due to the reduction of the strength, the time-dependent variation rela- tionship between cross sectional flexural capacity and fire time of prestressed concrete box girders was analyzed. The ex- perimental results indicate the flexural capacity of cross section decrease as a quadratic parabola type with fire time, and the decay extent increase from the middle to the end of the span; the damage value of flexural capacity of cross section when the inside of box girders exposed to fire is greater; the time-dependent decay formula is proposed to solve the flexur- al capacity of cross section of prestressed concrete box girders, which is simple to perform, and can provide data guide for fire resistance design and assessment after fire.

关 键 词：桥梁工程 预应力混凝土箱梁 有限元 抗弯承载力 火灾 

分 类 号：U448.21[建筑科学—桥梁与隧道工程]