考虑抗力修正系数和静载试验效率的RC简支梁桥限载取值

Truck weight limits for simply supported RC beam bridges considering correction factors of resistances and static load test levels

为确定静载试验验证后钢筋混凝土简支梁桥的限载取值,提出一种考虑抗力修正系数和静载试验效率的钢筋混凝土简支梁桥限载分析方法。首先,以桥梁设计活恒载比值为基本参数,建立抗力下限值与验证荷载间的关系式,并构造考虑抗力左截尾数分布特征的限载分析模型。进而,根据钢筋混凝土梁抗弯承载能力设计表达式,计算与不同抗力修正系数和静载试验效率对应的结构安全等级一级桥梁限载系数。最后,通过分析现行规范桥梁汽车荷载效应与典型车辆荷载效应比值,提出典型五轴车辆的限载建议值。结果表明:抗力修正系数和荷载效率对桥梁限载取值有较为明显的影响;在相同设计活恒载比值下,抗力修正系数和静载试验效率越大,试验验证后桥梁容许的典型车辆总重限值也就越高;研究成果可为静载试验后桥梁的限载取值提供依据。

To determine the truck weight limits for simply supported RC beam bridges, an analytical method was presented for bridges with consideration of various resistances and static load test levels.Firstly, the live to dead load ratios were taken as the fundamental parameters in establishing the relationship between the lower limits of resistance and proof loads, and the left truncated distribution of resistance was introduced to develop an analytical model for determining truck weight limits for simply supported RC beam bridges.Then the ultimate design equation for RC beams was used as the basis for determining the truck weight limits.For each possible live to dead load ratio adopted by RC beam bridges, the truck weight limit factors were calculated corresponding to various correction factors of resistance and static load test levels for bridges designed with safety class Ⅰ.Finally, the ratios of load effects caused by design vehicles to those caused by typical trucks were analyzed, and truck weight limits of 5-axle truck were determined for bridges designed with safety class Ⅰ.The results show that the correction factor and static load test level have obvious influences on truck weight limits of bridges.For bridges designed with the same live to dead ratio, the allowable truck weight limits for tested bridges increase with the correction factors of resistance and static load test levels.The research results can be referred to for determining the truck weight limits for static load tested highway bridges.