Research On Direct Assessment Of Pontoon With Grid Structure Roof

With the improvement of living standards,people are also richer in leisure.Dance and light show on water,which is a new kind of night cultural entertainment project,has attracted many tourists.Because the Three Gorges Reservoir area has the outstanding natural conditions for dance and light show on water,Return to Three Gorges show locate at Nanmentuo water area,Fengjie County,Chongqing City.In this show,tourists can be shocked by the natural beauty and cultural charm.Spectator seats pontoon is the key part of the infrastructure construction of this show.In order to enhance the experience of tourists,the spectator seats pontoon has a large scale,and the structure is special and complex,which is quite different from normal pontoon.Meanwhile,this pontoon also has a gird structure roof.In order to properly analysis the structure strength of the spectator seats pontoon,with the help of ship rules,steel structure rules and building structure rules,the structure strength of this pontoon is calculated by full ship direct strength assessment using finite element method(FEM).This paper introduces the basic theory of FEM and basic technology in full ship direct strength assessment,and then summarizes a calculation flow of full ship direct strength assessment.The fast modeling method of MSC.Patran is introduced,and also the static balancing,dynamic balancing,calculating of bending moment &shear curve which coding by PCL(Patran Command Language).This paper also analysis the basic theory and advantages of inertial relief and boundary conditions method.After calculating the structure strength by FEM in Nastran,the comparison of inertial relief and boundary conditions method shows that it is reasonable to use inertial relief.Contrasted with the strength,rigidity and stability standard,the components of pontoon and roof structure meet the requirement of rules.By analyzing the rigidity coupling between pontoon and roof,the result shows that the deformation of pontoon has adverse effect on roof structure,while the roof structure could decrease the deformation and stress of pontoon.In order to reflect the real deformation and stress by calculating the roof model separately,two kinds of forced displacement boundary conditions are analyzed.This paper summarizes the method in FEM direct strength assessment of ship which has large span structure,and it provides a reference for the direct strength assessment and finite element analysis of the similar ship.