Research On Structural Design And Safety Assessment Methods For Prefabricated Floating Wharf

Compared with traditional fixed docks,floating docks have the advantages of low construction cost,good flexibility,and strong movability,and can better adapt to the changes in the marine environment and the different needs of ships,thus having broad application prospects.The floating dock is located in a complex marine environment and needs to endure the impact of harsh sea conditions for a long time.The instantaneous increase in stress in the local structure can lead to the failure of the overall structure,which is one of the urgent problems that need to be solved for the floating dock.Therefore,the safety assessment of the floating dock structure itself is of great significance.This thesis proposes an assemblyable multi-module floating dock design scheme and designs the main structure.Based on the finite element analysis method,the direct strength calculation method is used to conduct overall strength analysis of the main structure of the multi-module floating dock.The specific research content includes:(1)Based on the transverse float configuration scheme of the multi-module floating dock,a detailed structural design scheme is provided.The floating dock is composed of an upper main structure,lower columns,and floaters.The main structure of the dock adopts a longitudinal skeleton design,which is composed of steel plates and steel bars;the columns and floaters adopt a plate design,which is composed of steel plates.At the same time,the safety assessment of the floating dock structure is given,including the safety of the main structure,mooring system,and connection structure.(2)Referring to the DNV specification,a strength analysis method for the multi-module floating dock is established.Taking a typical island reef sea area in the South China Sea as an example,three design examples of single-module floating dock connections are given.Based on this,the overall finite element model of the floating dock is subjected to overall strength analysis using the direct calculation method.Firstly,the three-dimensional potential flow theory is used to calculate the wave load response spectrum of the floating dock.The results show that the longitudinal torque load in the wave load of the floating dock is the largest.Further,the overall strength analysis of the main structure of the floating dock is carried out using the design wave method.The results show that the stress is generally greater than the allowable stress,and the maximum stress area is the connection between the platform and the column,which reaches 726 MPa.(3)For the multi-module floating dock,a plug-in hinge connection structure configuration scheme and structural design scheme are proposed,and the strength calculation method of the connection structure is established.The floating dock load response is obtained by conducting hydrodynamic time-domain analysis on the dock.Based on the penalty function contact model in the nonlinear finite element method,the strength and deformation of the connection structure are analyzed.The calculation results show that the stress and deformation distribution of the connection structure calculation model are reasonable and meet the design requirements.(4)For the area where the stress of the main structure of the floating dock is high,three improvement schemes are proposed,including the reinforcement scheme of adding plate ribs,the scheme of adding transverse braces,and the longitudinal floater configuration scheme.The strength calculation is carried out for the three improvement schemes,and the calculation results show that the reinforcement scheme of adding plate ribs has the best improvement effect,and the structural stress is significantly reduced,with a maximum reduction of 54%,and the strength of the main structure of the dock meets the design requirements.The research results of this thesis can provide reference for the future design and strength analysis of floating dock configurations.