考虑抗扭性能影响的多梁式矮箱梁桥荷载横向分布计算

目前对于多梁式矮箱梁桥的荷载横向分布计算采用刚接梁法，或采用有限元软件建立模型计算，但以上2种方法都未将抗扭刚度的影响考虑在内。因此，以上采用的2种计算分析方法不能对结构的特性进行准确模拟计算，也不能十分准确地对桥梁技术状况以及承载能力进行评价。为此，基于传统刚接梁计算荷载横向分布方法，在建立柔度系数矩阵时加入考虑主梁和翼板的约束扭转作用，提出一种适用于多梁式矮箱梁桥的荷载横向分布计算方法。为验证该方法的正确性，以某20 m跨径预制PC箱梁桥为对象，采用考虑抗扭刚度、未考虑抗扭刚度的刚接梁法和有限元数值模拟方法（梁格模型和板单元模型）计算其荷载横向分布系数，并与场地试验（中载和偏载2种工况）实测结果进行验证对比。结果表明：所提出的横向分布计算方法比未考虑箱梁主梁和翼板扭转的刚接梁法计算精度更高，也更接近实桥受力特点；同时，梁格模型、板单元模型与所提出的横向分布计算方法所得计算结果整体趋势基本上一致，相比于有限元数值模拟计算结果，采用该横向分布计算方法所得应变和挠度横向分布与实测结果更为接近，且偏差都在20%以内；该方法可在现场场地试验和桥梁承载能力评定中替代复杂的有限元数值计算方法，为预制矮箱梁桥场地试验和桥梁技术状况及其承载能力的评定提供较为准确的理论参考依据。

Calculation of Transverse Load Distribution of Multi-beam Short Box Girder Bridge Considering Influence of Torsional Resistance

To calculate the transverse load distribution of a multi-beam low box girder bridge, both the rigid-jointed beam method and numerical calculations are generally adopted.However, these methods do not consider the torsion of the main girder and the wing plate. Hence, the rigid-jointed beam method and finite element modeling calculation analysis can not accurately simulate the characteristics of the structure, which creates some deviations in the evaluation of the technical condition and bearing capacity of the bridge. In this study, based on the calculation method of the load transverse distribution by the rigid-jointed beam method, a calculation method of load transverse distribution suitable for a multi-beam low girder bridge is proposed by considering the restrained torsion action of the main beam and wing plate when forming the flexibility coefficient matrix.To verify the correctness of the method, a 20 m prefabricated box girder bridge was sampled, and verifies the correctness of this method by using the considering torsional stiffness and not considering torsional stiffness of rigid-jointed beam methods, the finite element numerical simulation method, the field test results.The results show that the accuracy of the calculation results for the load transverse distribution method adopted in this study is higher than that of the calculation method of the rigid-jointed beam method without considering the torsion of the main girder and wing plate of the box girder. Additionally, it is closer to the mechanical characteristics of a real bridge compared to the traditional calculation method. Meanwhile, the calculation results of grillage and plate element models are basically the same as calculation results of the transverse distribution presented in this study. In evaluating the transverse distribution of deflection or strain, the three methods were relatively close.This shows that the calculation results of the transverse distribution presented in this study are closer to the field test values than those of the grillage and plate element models. Furthermore, the deviation between the calculated results and the experimental values of the transverse distribution under the three methods is less than 20%. Above all, in the field test and evaluation of the bridge bearing capacity, the numerical calculation method of the complex finite element model can be replaced by the method presented in this study, which provides a more accurate theoretical reference for the field test of a prefabricated low box girder bridge and evaluation of bridge technique condition and bearing capacity.