半潜式平台极限状态评估

对某半潜式钻井平台,采用ANSYS建立有限元计算模型,进行了典型波浪荷载作用下平台非线性垮塌性分析,不考虑几何非线性和初始缺陷的影响。分析结果表明,平台最终的失效形式和水动力荷载作用形式十分相关,初始失效部位和最终失效状态各不相同。文中对ANSYS计算模型和SESAM计算模型进行了对比,在相同的荷载条件下分别计算了两个模型,比较ANSYS计算结果和SESAM计算结果及ABS和DNV规范理论结果,三者结果吻合较好。对非线性垮塌分析结果进行了讨论,通过对截面力作用形式的分析,建立了两类半潜式平台极限状态方程。文中半潜式平台非线性垮塌分析结果可以作为基于ABS和DNV规范的半潜式平台极限状态的基准性研究。

Assessment of Ultimate Strength of Semi-submersible Platform

This paper deals with evaluating the ultimate strength of a typical drilling semisubmersible platform.The progressive collapse of the object platform subjected to characteristic hydrodynamic loads is investigated using nonlinear finite element analysis with ANSYS.Material nonlinearities are taken into account without giving consideration to geometrical nonlinearities and geometrical imperfections.Initial failure points and final collapse states of the whole platform are the main concern of ultimate global strength analysis.It can be found that the last collapse modes of semi-submersible platform are closely related to corresponding characteristic hydrodynamic responses.The differences between each collapse mode are presented and compared.Simulation results are compared with theoretical predictions by DnV rules and ABS rules.The numerical model is verified against another model developed with SESAM program.Calculations of the two models are carried out under the same wave conditions and their results of calculation are compared by form of a chart.Simulation results of progressive collapse analysis are discussed and the corresponding ultimate limit state formulations are developed.The results on the nonlinear finite element analysis can serve as a benchmark reference to the theoretical predictions of semi-submersible platform based on ABS and DnV rules.