超重车辆对公路桥梁安全性的影响

Influence of Overweight Vehicles on Bridge Safety

根据结构可靠度理论,深入研究了公路超重运输车辆对钢筋混凝土受弯构件安全性的影响规律。首先,以恒载和汽车荷载作为安全性分析的最基本荷载组合,通过引入汽车活载影响系数,构造考虑不同汽车超重水平因素的结构功能函数,提出了基于一次二阶矩法的超载桥梁安全性分析数学模型。进而,以85桥梁规范和04桥梁规范钢筋混凝土受弯构件承载能力极限状态设计表达式为依据,按《公路工程可靠度设计统一标准》建议的抗力与荷载效应统计参数,详细计算了不同活载影响系数对钢筋混凝土受弯构件可靠指标的影响规律。计算结果表明,超重运输对钢筋混凝土受弯构件可靠指标有显著的影响,在活载影响系数取值一定的情况下,设计采用的汽车荷载效应与恒载效应所占比值越大,超载对桥梁结构安全性的影响越明显。

Based on structural reliability theory, the influence of highway overload vehicles on the safety of RC flexural members is examined. First, setting the dead load and vehicular load as the most basic load combination for safety analysis and introducing vehicular live load influence coefficient, the structural performance function with several levels of overloaded live loads is built, and a mathematical model for analyzing the safety of bridges is presented based on the single second-order moment method. Then, based on the limit state design expressions of the bearing capacity of RC flexural members specified in 85 edition and 04 edition of bridge design specifications, according to the statistical parameters of resistances and load effect suggested by Unified Standard for Reliability Design of Highway Engineering Structures, the influence of different live load influence coefficient on the reliability index of RC flexural members is calculated. The calculation result indicates that （ 1 ） the overload vehicles has significant impact on the reliability index of RC flexural members ; （2） given the value of live load coefficient, the greater ratio of vehicular live load effect to dead load effect adopted in the design of bridges will result in greater overload effect on structural safety of existing bridges.