大气环境下的钢筋混凝土桥梁时变可靠度分析

Time-dependent reliability analysis of reinforced concrete bridge under atmospheric environment

为了探究钢筋混凝土桥梁抗力退化对桥梁可靠性能的影响,综合考虑一般大气环境下混凝土强度、钢筋强度、混凝土与钢筋黏结性能的降低,建立普通钢筋混凝土桥梁的抗力退化时变模型,分析规范车辆荷载作用的桥梁时变可靠度。研究结果表明,(1)一般大气环境下,桥梁抗力随着服役时间的增加而减小,其中钢筋强度退化对桥梁抗力的影响最大,其次是钢筋与混凝土黏结性能降低,而混凝土强度退化对桥梁抗力的影响相对较小;(2)桥梁可靠指标随着服役时间的增加而减小,密集行车占比越大,桥梁承载能力失效的概率就越大;非平稳车载作用下的桥梁可靠指标小于平稳车载,桥梁需要维修补强的时间比平稳车载提前;(3)多梁式简支梁桥在建造时应该提高边梁的安全储备,在管养时可以采取限载措施进行干预。

In order to explore the influence of resistance degradation of reinforced concrete bridges on the reliability of bridges,this paper established a time-varying model of resistance degradation of ordinary reinforced concrete bridges by comprehensively considering the reduction of concrete strength,reinforcement strength and bond performance of concrete and reinforcement in general atmospheric environment,and analyzed the time-dependent reliability of bridges under vehicle loads.The results show that:(1)In general atmospheric environment,the resistance of bridge decreases with the increase of service time.The degradation of steel strength has the greatest impact on the resistance of bridges,followed by the reduction of bond between steel and concrete,while the degradation of concrete strength has relatively small impact on the resistance of bridge.(2)The reliability index of bridge decreases with the increase of service time.The larger the proportion of intensive traffic,the greater the probability of failure of bridge bearing capacity.The bridge reliability index under the action of non-stationary vehicle is less than that under the action of stationary vehicle,and the bridge needs to be repaired earlier than that under the action of stationary vehicle.(3)During the construction of multi beam simply supported bridge,the safety reserve of side beam should be improved,and the load limiting measures can be taken to intervene in the management and maintenance.