Robustness Evaluation And Performance Analysis Of Tension Leg Platform With Multiple Broken Tendons

Based on the nonlinear coupling effect of TLP hull and tendons,this paper studies the coupling dynamic responses of TLP and the mooring characteristics with multiple broken tendons.The relationship between the tendon failure positions and TLP transient responses is investigated emphatically.The tension redundancy and the redundancy standard deviation indicators are created to conduct deterministic robustness analysis.Moreover,considering the randomness of environmental loads and materials,the probability analysis of progressive failure is carried out.This study finds that:Since the motion of the out-of-plane degrees of freedom has rigid feature,the transient response of the platform heave,roll and pitch is more pronounced with multiple broken tendons.the tendon failure positions have close correlations with TLP dynamic responses.The heave,pitch and roll responses of TLP reach the maximum when there is failure of two tendons located in the same column,its intermediate responses occur with tendon failure in the same pontoon and minimum responses occur with tendon failure in diagonal columns.Various asymmetry factors,including tendon failure positions and wave directions caused by the environmental loads,may lead to a surge of TLP response in yaw with multiple broken tendons.The tension redundancy of the remaining tendon system indicates the average reserve level after multiple tendon failure.The redundancy standard deviation illustrates the discretization of the remaining tendon system.If the tension redundancy of the multiple tendons failure system is high and the redundancy standard deviation is small,TLP tends to have a good robustness.It is also seen that TLP cannot survive in the conditions of 100-yr and 1000-yr hurricane after two tendons break in the same column or same pontoon.Considering the random distribution of environmental load and structural materials,the continuous failure probability of the platform with multiple broken tendons is calculated.It is found that the more concentrated the failure position of the tendon,the greater the probability of continuous failure of the platform.Failure of two tendons located in the same column tends to be the most dangerous initial condition.A method combining comprehensive deterministic analysis and probabilistic analysishave been proposed to evaluate the robustness of TLP system.