中文摘要：

本文采用有限元法与强度穩定综合理论（combinedtheoryofstrengthandstability,CTSS）公式研究箱型梁的极限强度问题.揭示了有限元计算方法的不穗定性,结合Vasta的始屈弯矩法提出箱型梁结构的极限弯矩简化计算公式.通过两个箱型梁结构的实例计算表明,该公式的计算结果相对于试验结果的误差在10%以内,且与非线性有限元法相比有着简单、穗定的优势,可以为工程设计提供参考.

英文摘要：

In this study, we used the finite element method and the combined theory of strength and stability （CTSS） to determine the ultimate strength of the box girder. Due to the instability of the finite element method a- lone,we propose a calculation formula that simplifies the ultimate bending moment of the box girder by its combina-tion with the initial-flexion bending moment method defined by Vasta. In two calculation cases of the box girder structure,our test results show that the calculation errors associated with this formula are less than 10%. In addi-tion ,in comparison with the nonlinear finite element method,our proposed method is simple and stable,and can provide a reference for engineering design.