不同抗力水平公路桥梁限载分析模型

针对钢筋混凝土中、小跨径简支梁桥，提出一种适用于不同设计荷载等级或抗力衰减桥梁的限载取值简化分析方法。首先，通过引入抗力修正系数， 构造钢筋混凝土梁受弯破坏极限状态函数。进而，以规范建议的钢筋混凝土受弯抗力、恒载效应概率密度函数为依据，提出考虑抗力修正系数的桥梁限载简 化分析模型。在此基础上，以04规范桥梁的设计抗力水平为基准，以设计采用的活恒载比值为基本参数，计算与不同抗力修正系数对应的桥梁限载系数。最 后，以13m钢筋混凝土空心板梁为例验证限载分析模型，通过分析限载系数和典型车辆限载取值，给出了限载取值的修正方法。结果表明，按所提限载分析 模型推算的限载值均有一定的安全储备，可用于不同抗力水平桥梁的限载分析。

Analytical model for determining weight limits of highway bridges with various resistance levels

In order to determine the weight limits of simply supported RC short-and medium-span highway bridges, a simplified analytical method, which is applicable to different design load classes or attenuations of resistance, was proposed. Firstly, by introducing the correction factor of resistance, the limit state function of flexural failure of RC beams was established. Secondly, according to the probability density functions for flexural resistance and dead load effects of RC highway bridges suggested in the code, a simplified analytical model for determining the weight limits of highway bridge with correction factor considered was proposed. Furthermore, based on the resistance level as specified in 2004 edition of the code, the coefficients of weight limits corresponding to different correction factors of resistances were computed with the ratios of live load to dead load adopted in bridge design taken as the fundamental parameters. Finally, with the 13m RC box beam taken as an example, the feasibility of the simplified analytical model was verified, and the modification method of weight limits was also proposed through analyzing the coefficients of weight limits and the weight limits of typical trucks. The results show that a certain safety reservation can be achieved if the proposed model is employed to calculate the weight limit values, indicating that it can be used for determining the weight limits of highway bridges at different resistance levels.