除冰盐环境下预应力混凝土箱梁桥可靠度分析

Reliability analysis of prestressed concrete box girder bridge under deicing salt environment

为研究除冰盐环境下受预应力筋的腐蚀效应及其对预应力混凝土梁桥可靠度的影响,以某桥为工程背景,考虑氯盐环境、混凝土时变效应、腐蚀电流密度及氯离子侵蚀过程等因素的不确定性,建立了预应力混凝土箱梁桥的时变可靠度模型,研究了时间、腐蚀电流密度及保护层厚度等参数对结构承载力的影响,计算了该梁桥在100a设计期内的失效概率,并开展了参数敏感性分析。研究结果表明:不考虑混凝土强度的时变效应结构计算结果是偏不安全的;腐蚀电流密度对失效概率的增加速率有影响;在一定范围内,增加保护层厚度能延缓失效概率的增加。

The corrosion effect of prestressed tendons under deicing salt environment and its influence on the reliability of prestressed concrete girder bridges were studied.Taking a bridge as the research background,the effects of the chloride environment,concrete time-varying effect,corrosion current density and chlorine ion erosion process and other parameters were considered,and the time-dependent reliability model of prestressed concrete box girder bridge was established.The influence of concrete strength with time,corrosion current density and the thickness of protective layer on the bearing capacity loss of the prestressed concrete box girder bridge was studied.The failure probability of the bridge during the design period of 100 awas calculated,and the parameter sensitivity analysis was carried out.The results show that the structural calculation results without considering the time-varying effect of concrete strength are unsafe.The corrosion current density affects the growth rate of failure probability.In a certain range,the increase of protective layer thickness can delay the increase of failure probability.