悬臂板内力计算方法研究与应用

Research and Application of Calculation Methods for Internal Forces of Cantilever Slabs

摘要:

针对公路桥梁长悬臂板结构内力计算问题，系统比较了规范法、沙柯公式法、贝达巴赫公式法与有限元法四种计算方法的适用性与精度。通过建立不同悬臂长度（2.25、2.75、3.25 m）的板单元模型，结合《公路桥涵设计通用规范》（JTG D60—2015）荷载标准，分析了车轮荷载作用下的根部弯矩。结果表明，规范法由于忽略板的双向受力特性，计算结果偏小20%～30%，不适用于长悬臂板；而沙柯公式、贝达巴赫公式与有限元法结果较为接近，其中有限元法结果最为保守，建议作为设计依据。研究还提出了基于后轴弯矩估算总弯矩的简化计算方法，为长悬臂板设计提供了实用参考。研究结论表明，随着悬臂长度增加，不同计算方法间的差异逐渐增大，在实际工程中应综合考虑计算精度与效率，选择合适的计算方法。

Abstract:

Aiming at the problems of calculating structural internal force of long cantilever slabs in highway bridges, the applicability and accuracy of four calculation methods of the specification-based approach, the Sawko formula method, the Baider-Bahkt formula method and the finite element method are systematically compared. By establishing the plate element models with different cantilever lengths (2.25 m, 2.75 m and 3.25 m) and combined with the load standards in the General Code for Design of Highway Bridges and Culverts (JTG D60—2015), the root bending moments under wheel loads are analyzed. The results indicate that due to ignoring the bidirectional force characteristics of the slab, the calculation result of the specification-based approach is 20%~30% smaller and is not applicable to long cantilever slabs. In contrast, the results of the Sawko formula, Baider-Bahkt formula, and finite element method are relatively close, in which the result of the finite element method is the most conservative, and is recommended as the basis for design. A simplified calculation method for estimating the total bending moment based on the rear axle bending moment is proposed, providing a practical reference for the design of long cantilever slabs. The conclusions show that as the cantilever length increases, the discrepancies among different calculation methods become more significant. In practical engineering, the computational accuracy and efficiency should be comprehensively considered to select an appropriate calculation method.