The dynamics of deep water subsea lifting operations in super-harmonic resonance via the harmonic balance method

The dynamics of deep water subsea lifting operations experiencing super-harmonic resonance is analysed in this study. The harmonic balance method is used to solve the non-dimensional equation of motion of the system and the results are compared with time domain integration and with an equivalent energy dissipation model for typical subsea lifting scenarios. It is demonstrated that 1:3 and 1:5 super-harmonic resonances represent significant features of the response of the system and can lead to large dynamic forces in the cable, which may violate the structural limits of the system in real operations. The harmonic balance method presents results almost as accurate as the time domain integration but up to 25 to 35 times faster, while the equivalent energy dissipation model is not able to represent the super-harmonic resonances. Consequently, taking into account the dynamics introduced by super-harmonic resonances is necessary in the analysis of subsea lifting operations, as it can be the limiting design criterion in certain scenarios, and the harmonic balance method can be used as a fast and accurate method to solve this problem.     

基于牛顿迭代法的潮汐模型高低潮时计算方法*

在由调和分析方法建立了潮汐潮位预报模型后,利用牛顿迭代法给出了一种快速求解潮汐潮位预报模型的高低潮时方法.利用连云港的潮汐潮位预报模型,分别通过不同的求解高低潮时的方法,对潮汐高低潮时进行了预报.计算结果表明,在满足同等精度条件下,求解高低潮时的牛顿迭代法具有计算量小、收敛速度快等优势.     

中美英规范在港工水电构筑物结构设计的差异

水电构筑物结构设计是港口工程设计的重要组成部分。以有限单元法为基础,对比中国的GB 50010—2010、美国的ACI 318 M-2014、英国的BS 8110-1:1997这3个规范在港工常规构筑物结构设计中的计算方法,得出中美英规范在港工构筑物的抗弯、抗剪强度、偏心受压强度计算和裂缝宽度、地基承载力验算的异同,并结合典型工程实例说明按照不同规范计算的具体步骤和差异。结果表明,按照美国或英国规范计算的港工构筑物结构的体积含钢量较大。