一、概述箱梁结构轻巧,抗扭刚度大,是大跨径梁式桥的主要结构形式,国内国外已普遍采用。箱形为一空间结构,计算比较复杂。目前国内公路系统作箱梁设计计算时,一般按杆系分析并乘以横向分布系数,以增大其纵向的计算弯矩来考虑纵向翘曲作用。但对于横向变形(畸变)及其内力的精确分布还缺乏正确的分析方法,故箱梁截面的选择和钢筋布置往往不符合结构的实际工作状态,出现裂缝的情况屡有发生。近年来还由于桥面净宽的需要,箱梁的横 First, an overview Box girder structure lightweight, torsional stiffness, is a major structural beam span bridge, domestic and foreign has been widely used. Box-shaped structure for a space, the calculation is more complicated. At present, the design and calculation of box girder in domestic highway system is usually based on the analysis of the bar system and multiplied by the lateral distribution coefficient so as to increase the longitudinal bending moment to consider the longitudinal warping effect. However, the accurate analysis of lateral deformation (distortion) and its internal force is still lack of accurate analysis, so the choice of box girder section and the arrangement of steel tend to not conform to the actual working state of the structure, and the occurrence of cracks frequently occurs. In recent years, due to the needs of the bridge net width, the horizontal cross-box