Reaction Process Of Jacket Steel Frame Under The Post-Earthquake Fire

In the exploitation of deep-sea oil and gas resources,the jacket steel frame plays a crucial role.Once suffering from earthquake disasters,serious secondary disasters will occur.Among them,the secondary fire caused by earthquake is the most likely secondary disaster,which will cause huge economic losses and casualties.At present,the research on the jacket steel frame mainly focuses on the mechanical behavior under the action of earthquake or fire.Usually,the jacket steel frame will be damaged after the earthquake,which will seriously affect and reduce the fire resistance of its.Therefore,it is of great theoretical value and practical significance to carry out research on the reaction process and failure mechanism of the jacket steel frame under post-earthquake fire action for fire prevention and earthquake emergency response of the jacket steel frame.In this paper,through experimental verification and parameter research,the fireresistance performance and failure mechanism of the jacket steel frame and T-joint under postearthquake fire were studied.The main contents are as follows:(1)Reasonable unit type and material constitutive model are chosen and meshing has been improved.Unstiffened tubular T-joint computational model is precisely established by validating existing experiment to test effectiveness and accuracy of computational model.By introducing the earthquake damage variable and forcing the fire load to unstiffened tubular Tjoint,the diameter-thickness ratio(?),the diameter ratio(?),the wall thickness ratio(?)and damage variable were studied under post-earthquake fire.(2)T-joints with internal ring stiffener was precisely established by validating existing experiment to test effectiveness and reliability of computational model.The diameter-thickness ratio(?),the diameter ratio(?),the wall thickness ratio(?),the thickness ratio(?)of ringstiffener and damage variable were researched.The reaction process,critical temperature,failure mode,stress distribution and displacement of T-joints with internal ring stiffener were studied under post-earthquake fire.(3)According to the results of parameter analysis,the failure mode,reaction process,critical temperature,the vertical displacement and stress distribution of unstiffened tubular Tjoint and T-joints with internal ring stiffener are compared and analyzed.The results show that the failure mode of reinforced T-joint and unreinforced T-joints in post-earthquake fire are the same,but the stress mechanism and energy dissipation mechanism are different.(4)The accurate calculation model of the jacket steel frame was established,and the seismic damage was imposed by introducing damage variables.The residual stress and residual deformation generated before were transferred to the subsequent fire analysis by restarting the analysis with ANSYS.Hazard identification method and fire explosion index method were used to determine the potential fire location of the jacket steel frame.By applying fire loads,disaster process,damage evolution law,critical temperature and failure mode of the jacket steel frame were studied under post-earthquake fire.To sum up,the reaction process,damage evolution law and failure mode of the jacket steel frame and T-joints were studied under post-earthquake fire by experimental verification and parameter study.The results have the important theoretical research value and realistic significance on fireproofing of the jacket steel frame and earthquake emergency.These results provide theoretical basis and technical support for fire and earthquake resistant of the jacket steel frame and have important theory value and broad application prospect on the formation,extension,control and assessment of major disasters and accidents.