Research On The Applicability Of The Orthotropic Steel Deck-Concrete Composite Pavement System

In order to improves the force situation of the orthotropic steel bridge deck and pavement at the same time,we setting up a high-performance concrete permanent structure layer(such as STC)between the orthotropic steel roof and the pavement to forming a combination pavement system.However,STC requires pretty high cost and very strict construction process conditions.In this paper,take Dongguan Waterway Bridge(closed rib)and Changhu Ramp Bridge(opening rib)as the project background,researched the mechanical properties of orthotropic steel bridge panels and the applicability of different pavement design methods based on the same cost,namely quivalents STC combination pavement system of the same cost to ordinary concrete combination pavement system with differents thickness of steel roof and longitudinal ribs,and their mechanical properties are further studied.The research results are as follows:First,the simplified model of segment is discussed by finite element method,including the model boundary conditions,grid size,vertical and horizontal range,and the most unfavorable load conditions etc.The mechanical properties and the relevant parameters of simplified orthotropic steel bridge panel model are determined by comparing the influences of parameter changes on the results.Secondly,this paper comparises and analyses maximum vertical displacement of bridge deck,the maximum longitudinal and transverse tensile stress changes before and after the orthotropic steel bridge deck and pavement layer combination.The results show that the combintion pavement system can reduce the mechanical indexes of orthotropic steel bridge significantly and favor the lower local stress of steel bridge deck.Thirdly,it analyzes the influence of different structure layer material to steel deck through establish the pavement system model which considering the steel deck and pavement composite effect.As the structural layer and steel bridge deck bear the force together,their load proportion increases with the increase of the structural layer stiffness,which the maximum displacement and stress of orthotropic steel bridge deck and asphalt layer decrease,while the stress of the structural layer increase.When using STC instead of asphalt as a pavement,the bridge deck stiffness increased by about 38% under the same conditions.Compared with the STC base,when using C60 concrete as the lower pavement,the stiffness between the two pavement systems is only about 2.4% diferent,indicating that the stiffness of the two combinations pavement system is basically the same.But the tensile stress of the C60 concrete pavement base has exceeded its tensile strength design value.Finally,this paper studies the stress performance of the orthotropic steel bridge deck's ordinary concrete composite pavement system with the change of different thickness of deck and longitudinal ribs.According to the same costs principle,the STC basements are equivalented to steel roof thickness or longitudinal rib thickness.Compared with the same cost of STC composite pavement system,the ordinary concrete composite pavement system with addition steel roof thickness and longitudinal ribs thickness can reduce the stress and displacement peak level of orthotropic steel bridge panel significantly.Besides,the latter requires simple construction process.So the equivalent pavement system is more suitable.In addition,it is found that the difference between the closed ribs steel deck and opening ribs steel deck are mainly reflected in these areas:(1)The torsional stiffness of the longitudinal rib increases with the increase of longitudinal rib thickness.(2)Trsional effect of longitudinal rib causing a transverse principal stress increase in the transverse plate at the junction with the longitudinal rib under load,which is very unfavorable to the diaphragm.