薄壁梁约束扭转极限承载能力简化计算方法研究

Research on the simplified calculation method of thin-walled girder constrained torsional ultimate capacity

为了快速并有效地计算海洋平台等薄壁箱型梁结构的约束扭转极限承载能力,进行了薄壁梁约束扭转极限承载能力简化计算方法研究。基于塑性极限状态分析理论,提出了薄壁梁约束扭转极限状态应力分布假设,将薄壁梁视作为一系列由主要支撑构件和扶强材支撑的板格,推导了薄壁梁约束扭转极限承载能力上限的计算公式。应用非线性有限元方法验证了所提假设和计算公式的精度,将所提方法应用于箱型梁模型和半潜平台的约束扭转极限承载能力的计算分析,并与非线性有限元结果进行了比对,结果表明,本方法具有较高的精度,可用于海洋平台等薄壁梁的扭转极限承载力上限的估算。

In order to quickly and effectively calculate the constrained torsion ultimate capacity of thin-walled box girder structures such as offshore platforms, a simplified calculation method for the constrained torsion ultimate capacity of thin-walled beams was studied. Based on the theory of plastic limit state analysis, the hypothesis of stress distribution in the limit state of constrained torsion of thin-walled beams was proposed. The thin-walled beam was regarded as a series of panels supported by main supporting members and stiffeners, and the calculation formula of the upper limit of the constrained torsional bearing capacity of thin-walled beams was deduced. The non-linear finite element method was used to verify the accuracy of the proposed hypothesis and calculation formula. The proposed method was applied to the box girder model and the calculation analysis of the restrained torsion ultimate capacity of the semi-submersible platform, and the results were compared with the non-linear finite element results. The comparison results show that the method proposed in this paper has high accuracy and can be used to estimate the upper limit of the torsional ultimate capacity of thin-walled beams such as offshore platforms.