The forces acting on bridge structural elements caused by live loads are computed by live load models defined in design codes. In most cases, such live load models are defined by studies performed on girder bridges, where extreme values of shear forces and bending moment are intended to be predicted. This paper shows that when code live load models are applied to truss bridges, the estimated forces in some structural elements may not be representative of those caused by actual traffic. Three WIM (weigh-in-motion) databases, which are recorded on roads in Mexico, are used as real traffic data. The results suggest that current code live load models are not entirely adequate to estimate forces in structural elements of truss bridges.

翻译：由活载作用在桥梁结构构件上的力是通过设计规范中定义的活载模型计算得出的。在大多数情况下，这类活载模型是基于对梁桥的研究定义的，其目的是预测剪力和弯矩的极值。本文表明，当规范的活载模型应用于桁架桥梁时，某些结构构件中估算的力可能无法代表实际交通引起的力。三个在墨西哥道路上记录的WIM（动态称重）数据库被用作实际交通数据。结果表明，当前的规范活载模型并不完全适用于估算桁架桥梁结构构件中的力。