刚度高温衰变的混凝土箱梁预应力时程损失研究  

Prestress Loss of Concrete Bridges with Box Girders Based on Decay of Stiffness Exposed to High Temperature

作　　者：张岗[1,2] 刘天龙[1,2] 王翠娟[3] 程海鲲 

机构地区：[1]长安大学公路学院,西安710064 [2]长安大学旧桥检测与加固技术交通行业重点实验室,西安710064 [3]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6期66-71,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;2013G2211004;2014G2213002);国家留学基金(201406565013)

摘　　要：采用热力耦合计算方法,考虑延火方式、延火时间、钢束型式等参数,通过材料刚度高温衰变的虚拟层截面等效计算,分析了不同型式的混凝土箱梁预应力时程（沿时间变化）损失分布,研究了不同延火方式的预应力时程损失变化率,揭示了刚度高温衰变的混凝土箱梁预应力时程损失规律。结果表明：混凝土箱梁的预应力损失变化率受延火方式、延火时间和钢束型式的影响显著;随延火时间的增加,混凝土箱梁预应力时程损失呈指数型式增大;延火前期混凝土箱梁预应力时程损失增长率大,延火后期混凝土箱梁预应力时程损失增长率小,延火前期和延火后期的时间分界点为40~60min;拟合建立了混凝土箱梁预应力时程损失计算公式,公式简洁。此研究可为火灾下预应力混凝土梁桥的刚度退化及灾后评价提供依据。The thermal-mechanics coupled method was applied to study the prestress loss law of concrete bridges with box girders based on stiffness decay of material exposed to high temperature.Parameters including fire scenarios,fire time and the distribution of prestressing strands were considered.Based on the equivalent calculation of cross sectional virtual layer due to the reduction of the stiffness,the time-dependent distribution of prestress loss with different strands was analyzed,and the variation rate was proposed under different fire scenarios.The experimental results show that variation ratio of prestress loss for concrete bridges with box girders affected obviously by fire scenarios,fire time and the distribution of prestressing strands.The time-dependent loss of prestress for concrete bridges with box girders present an index increase with extending of fire time.The increase rate of the time-dependent loss of prestress for concrete bridges with box girders during the fire prophase is rapid,the increase rate of the time-dependent loss of prestress for concrete bridges with box girders during the fire anaphase is slow,and the demarcation point of time between fire prophase and fire anaphase is 40~60min.The time-dependent formula of prestress loss for prestressed concrete bridges with box girders was proposed,which is concise.Our research can provide foundation for the stiffness degradation mechanisms of prestressed concerte bridge exposed to fire and assessment of prestressed concerte bridge after fire hazard.

关 键 词：桥梁工程 预应力混凝土箱梁 有限元 时程损失 高温 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]