Optimization Design Of Orthotropic Steel Bridge Deck Pavement Based On Response Surface Method

Fatigue problem of the orthotropic steel deck and pavement disease are two main factors reducing the service life of long span steel box girder bridges.Scholars across the world have conducted a lot of research on this issue and achievement acquired have solved some practical problems effectively,but there are still some shortcomings.Most of the previous researches did not realize that stress condition of fatigue detail can be improved if taking pavement layers into consideration;On the other hand,due to the heavy traffic flow,serious overloading and climate differences in different regions,there is not yet a complete theoretical system for bridge deck pavement design in our country.Bridge deck pavement design still needs in-depth study.Taking the Nanxi Yangtze River Bridge as an example,typical fatigue detail stress was analysed by establishing a finite element model of orthotropic steel deck system considering or not considering the pavement layer.Influence on stress condition of the U ribs-bridge deck welds and the openings position of the diaphragms caused by change of the pavement layer thickness,the elastic modulus and the contact state between the pavement layer and the steel deck top slab was studied.The results show that fatigue detail stress of the orthotropic steel deck system is reduced when the pavement layer is considered.Fatigue detail stress can be greatly improved while appropriately increasing the thickness of the pavement layer,using high-performance concrete or maintaining the good contact between the pavement layer and the steel deck top plate.Reduction of the top deck-U rib connection detail stress is more pronounced compared with other detail stress.A design index system including transverse tensile stress,interlaminar shear stress,and deflection was proposed according to disease classify of orthotropic steel deck pavements.Orthogonal experimental design method was used to study the influence of orthotropic deck structural parameters and paving layer parameters on design index system under the most unfavorable wheel load.The results show that:Elastic modulus of pavement has the most significant influence on three design index;Transverse tensile stress and deflection value gradually decrease as the thickness of pavement layer increases,and the interlayer shear stress increases till to a certain value and then decreases gradually.;Change of deck thickness has less influence on the transverse tensile stress and deflection value,and the shear stress decreases with the increase of the thickness of steel deck.With the purpose of reducing quality of the orthotropic steel bridge deck system and the transverse tensile stress of the pavement,taking the interlaminar shear stress and the deflection span ratio of the pavement layer as constraint variables,design variables determined according to the orthogonal test design results,optimization design of orthotropic steel deck system based on response surface method optimization theory was carry out.Transverse tensile stress of the pavement layer after optimization is reduced by 0.99%compared with the original design,and the quality of the orthotropic steel deck system is reduced by 2.12%compared with the original design.The FEM simulation calculation results are consistent with the optimized results based on the response surface,which demonstrates that the optimized value obtained by the optimization method satisfies the requirements.