研究了全跨和半跨荷载组合下荷载效应函数的特性。首先分析了荷载效应函数为非线性的原因。然后在多个实例分析的基础上,提出了一个全跨和半跨荷载组合作用下荷载效应函数的一般模型。该模型无论是在构件层次上还是在体系层次上都具有较高的精度。最后根据此函数模型,讨论了荷载效应曲线的非线性程度。结果表明荷载效应曲线为抛物线或双曲线。这为结构可靠度计算提供了参考。 The characteristics of load effect function under full-span and half-span loads are studied. Firstly, the reason why the load effect function is nonlinear is analyzed. Then, based on the analysis of several examples, a general model of load effect function under full-span and half-span load combination is proposed. The model has high precision both at component level and system level. Finally, according to this function model, the degree of nonlinearity of the load effect curve is discussed. The results show that the load effect curve is parabolic or hyperbola. This provides a reference for structural reliability calculation.