Research On Design Of Vehicle Deck Under Multi-wheel Loading And Transverse Stiffener

With the unique cargo handling form of roll on and roll off,vehicle ro-ro carrier has advantages of high handling efficiency and low requirements on terminal machinery.Therefore,vehicle ro-ro carrier has promising prospect in our country's automobile foreign trade.As the main structure of vehicle ro-ro carrier,vehicle deck plays the role of bearing vehicle wheel loading.Due to the relatively small contact area between tire and deck,wheel loading is a kind of local load,which causes sharp stress and deformation of the deck to concentrate near the loading patch.The research on the design of vehicle deck structure is meaningful to ensure the structural safety in operation.At present,the design formula of vehicle deck thickness and stiffener section modulus in classification society rules are mainly aimed at single wheel loading.However,the overall consideration is not comprehensive enough,or equivalent rationality is not stated in the case of a multi-wheel loading with multiple tires on one side of the vehicle axle.In addition,when the weight of ro-ro carrier is too heavy,the designer can consider adding a stiffener between web beams in traditional longitudinal framing deck.As a result,the design thickness of deck might decrease,and the weight of ship might reduce although the adding stiffeners.This paper focuses on the above two issues.In this paper,the structural design of the vehicle deck under the multiwheel loading and new transverse stiffener form are studied.It mainly includes four parts: Firstly,based on the PCL language,the tool of wheel loading automatically load and post-processing is developed,which can be used to assist the automatic loading and post-processing of the multi-case wheel loading conditions;Secondly,for thickness design of vehicle deck,based on FEM method of linear elastic theory,a large scale of calculation was carried out by changing the wheel loading sizes and the panel sizes,and the coefficients related to these sizes were analyzed and validated in the DNV rule design formula.On the basis of analysis above,the design method of vehicle deck thickness is obtained,and the stress results under the most dangerous load cases are obtained by changing the position of the multi-wheel loading.Furthermore,the validity and applicability of two multi-wheel loading equivalent methods are studied.The recommended equivalent method and its applicability are given;Thirdly,when focusing on the secondary member,the wheel loading is reduced to the concentrated force.The reasonableness of the simplified treatment is investigated based on FEM method and the force conditions of secondary member is studied under 2 and 3 concentrated forces;finally,the effect of the new transversal reinforcement form structure of traditional longitudinal framing deck is studied to reduce the design thickness.