Dynamic Response And Damage Analysis Of Concrete Filled Double Skin Steel Tube Combined Jacket By Ship Collision

In recent years,with the increasing scarcity of land resources,marine energy development has become an inevitable trend,the ocean platform as a basic facility for offshore resource development,working in the harsh marine environment all year round,subject to accidental collision of ships,sea ice impact and other accidental loading situations occur from time to time.The structural damage caused by collision will lead to casualties and environmental pollution.Concrete filled double skin steel tube(CFDST)jacket platform leg is a new type of composite structure,compared to the empty steel tube has a higher load-bearing capacity and impact resistance,gradually in the offshore wind turbines and jacket platform and other marine engineering applications.CFDST jacket platform legs replace steel jacket platform legs to form a new type of concrete filled double skin steel tube combination jacket platform.Therefore,it is very important to study the anti-collision performance and damage of ship collision concrete filled double skin steel tube combination jacket platform(CFDST jacket platform)for engineering applications.In this paper,we use the nonlinear finite element method based on ABAQUS/Explicit to simulate the collision process of a ship impacting a conventional steel jacket platform as well as a concrete filled double skin steel tube combination jacket platform,and to analyze the influence of structural parameters of the jacket platform leg,collision position and collision angle and other parameters on the anticollision performance and damage of the jacket platform,the main work and results are as follows:(1)ABAQUS software was used to model and perform finite element analysis of falling hammer impact tests on concrete filled double skin steel tube members in the literature,and the finite element results were compared with the test data to verify the accuracy of the finite element modeling and the feasibility of performing collision problems.(2)The dynamic response of the conventional steel jacket platform and the concrete filled double skin steel tube combination jacket platform under ship collision is compared and analyzed,including structural stress-strain,collision force,displacement change and energy conversion.The results of the study show that: local depression and overall bending deformation of the jacket platform leg mainly occurs after the impact of the conventional steel jacket platform under low and medium energy collision loads;fracture damage at the jacket platform leg and support node occurs under high energy collision loads;CFDST jacket platform effectively increases the structural stiffness due to the concrete filled double skin steel tube jacket platform leg,compared with the traditional steel jacket platform legs,the local depression and overall bending of CFDST jacket platform legs are effectively controlled and no structural important node fracture damage occurs,which improves the anti-collision performance of the structural foundation of the jacket platform frame.(3)Based on the established finite element model of ship collision concrete filled double skin steel tube combination jacket platform,the full process collision mechanism is analyzed,and the effects of structural parameters of CFDST jacket platform leg,collision position and collision angle on the dynamic response of CFDST jacket platform under the collision load are analyzed.The results show that when the ship collides with the concrete filled double skin steel tube combination jacket platform,the performance of CFDST jacket platform leg,as the main energy absorbing and forcebearing component,directly affects the anti-collision performance of CFDST jacket platform.When the concrete filled double skin steel tube leg hollow ratio is controlled at about 0.6,the collision resistance performance of the jacket platform structure is optimal;the outer steel pipe yield strength and impact angle have obvious influence on the change of the dynamic response of CFDST jacket platform,while the inner steel pipe yield strength,concrete strength and impact height and other parameters have less influence.(4)In response to the problem of ship collision on the jacket platform,aluminum foam collision avoidance device is applied to protect the jacket platform foundation.By absorbing part of the ship collision energy through the compression deformation of aluminum foam,it will effectively reduce the dynamic response and structural damage of the jacket platform.After the finite element analysis of the ship collision jacket platform,the following conclusions are drawn: for low-energy collision,the aluminum foam protection device applied to the steel jacket platform and concrete filled double skin steel tube combination jacket platform can resist most of the collision energy;For high-energy collisions,the role of aluminum foam protection is reduced,mainly by the stiffness of the jacket platform structure itself to resist collision deformation,CFDST jacket platform structure of its own stiffness,and the combination of aluminum foam devices used to resist high-energy collisions with better results.