基于可靠度理论的中小跨径桥梁卡车载重限值研究

卡车载重限值标准直接影响实际汽车荷载水平及其分布特性以及桥梁等基础设施的服役性能。为分析中小跨径桥梁的卡车载重限值问题，该文首先基于可靠度理论建立卡车载重限值分析模型；其次，基于长期记录的WIM（Weigh in Motion）数据分析我国典型公路路段卡车荷载特性并确定需要进行载重限值研究的重载卡车车型，并根据我国当前中小跨径桥梁建设现状选择对卡车载重限值起控制作用的桥梁结构类型；最后，建立结构关键截面抗弯功能函数，选择多层次目标可靠指标，对各类型卡车的载重限值进行反向迭代分析，基于分析结果分别讨论目标可靠指标、区域荷载特性对卡车载重限值的影响，以及现行公路治超标准对中小跨径桥梁车辆限载的适用性。分析结果显示:各类型卡车载重限值随着目标可靠指标的增大有明显线性下降趋势；区域卡车荷载特性的差异对卡车载重限值有着不可忽略的影响；现行国家治超标准对中小跨径桥梁车辆限载具有较好的适用性，但建议各地区根据自身实际情况在国家公路治超标准的基础上进行微调。

RELIABILITY BASED RESEARCH ON TRUCK-LOAD LIMITATION OF MEDIUM-SMALL-SPAN BRIDGES

The standard of truck-load limitation owns an immediate influence on the actual vehicle-load level and on its probability distribution characteristics. Further, the standard may affect the serviceability of constructed infrastructures, for example, bridges. To investigate the truck-load limitation of medium-small-span bridges, a probabilistic method was firstly established. In the second part, the truck-load characteristics were discussed based on long-term WIM (weigh in motion) data and the typical truck types were extracted. Then the higher limits of trucks mass were obtained through the inverse iteration based on the established flexural performance functions and the selected multi-level target-reliability index. The affection of target-reliability index and the differences in regional-load characteristics on the limited truck mass were discussed based on the analysis results. Further, the applicability of current standard was analyzed through a comparison. The following conclusions were obtained from the analysis process:the limited truck-weight decreases linearly with the increase of target reliability index, besides this, the influence of differences in regional-load characteristics on the results is non-ignorable. The current standard of overload control is suitable for the load limitation of medium-small-span bridges. Nonetheless, it will be better for different regions to refine the regional-standard base on autologous conditions.