| Since the COVID-19 outbreak in 2020,the global economic & trade landscape has undergone profound changes,such as the shipping market especially the market of container vessel flourished as never before(even there is no any available container for some routes).At the same time,due to the widens of Panama Canal and the significantly improved of automation rate of loading & unloading in major ports,the very large container vessels(above12000TEU)are more and more favored in shipping market.Compared with middle or small container vessels,very large container vessels have obvious advantage of low unit costs and freight rate,which caused this kind of vessels become a hot spot in the newbuilding market.Due to very large,the high-rise lashing bridge should be adopted for this kind of container vessels.For all the equipment of very large container vessels,the weight of lashing bridge structure accounted for more in light weight.Therefore,the design and construction of large lashing bridge is one of the difficult and important points,and it is a great significance to further explore and study its design.This thesis took the lashing bridge of 23,000 TEU Container Vessel undertaken by a domestic shipyard as the research object.With the knowledge of structural mechanics and FEM,the structural design and pre-erection technology of multilevel large lashing bridge of very large container vessel was explored.The research contents mainly includes:(1)Two structural designs of lashing bridge are compared,which are Full A Frame(Plan I)and Non Full A Frame(Plan II).Based on the results of FEM analysis and weight estimation,Full A Frame(Plan I)which is the best one was selected as the basis for the follow-up work.(2)Based on the design scheme of Full A Frame,a variety of reinforcement schemes for the typical lashing bridge including platform,main diagonal brace 、 post and the structure of between platforms were designed.According to the result of strength analysis for such schemes,a better reinforcing structure obtained to achieve the goal of reducing the weight of the structure.Regarding the lashing bridge of some special position,not only the better reinforcement scheme is selected as per the strength analysis results of analyzing the load,the vibration analysis is also carried out to verify whether it meets the requirements or not.(3)Based on the analysis of the horizontal and vertical pre-erection for lashing bridge of23,000 TEU,the vertical pre-erection was adopted after combined with the allocation of site resource and other factors and 10 pieces of lashing bridge as a group will be erected.Meanwhile,the design of bed-jig,anti-tilt fixture and clamp device for this type of preerection was carried out to ensure the structural accuracy of the lashing bridge.(4)According to the actual lifting scheme of each sections of lashing bridge,firstly,for the horizontal lifting scheme of specified port side block and center block is optimized.Secondly,four different constraint schemes for vertical lifting of center block were selected to analyze.According to the results of maximum structural and deformation of such analysis,a reasonable and reliable constraint form is adopted.Finally,strength analysis was carried out for two schemes of the erection with vertical lifting(4 lifting points and 8 lifting points)and the scheme of 8 lifting points was adopted as the better lifting scheme for construction.The research results of this thesis will provide the guidance for the independent design and pre-erection scheme of lashing bridge structure of subsequent domestic very large container vessels. |
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