Analysis And Optimization Of Steel Deck Pavement Structure Under Various Fatigue Damage Behaviors

Cases of the steel bridge deck pavement structure being frequently damaged within 2-3 years after opening to traffic are common at home and abroad.Frequent repairing not only interferes with traffic seriously but causes severe damage to the main structure of the steel bridge.The reasons for the frequent occurrence of steel bridge deck pavement structural layer diseases are related to the harsh service environment of steel bridges as well as the current design of bridge deck pavement which mainly focus on controlling the ultimate damage of pavement structure and materials.The impact on fatigue damage effects is rarely considered which leads to most of the common diseases such as rutting,delamination problem,and cracks in bridge deck pavement.Therefore,in view of the above defects in bridge deck pavement design,this paper intends to take Wuhan Baishazhou Bridge as the research object,analyze the mechanical behavior of the bridge deck pavement structure under comprehensive effects of vehicle-mounted and temperature as well as various fatigue damages effects,reveal the reasons of the frequent occurrence of early diseases of bridge deck paving structures,and propose the corresponding optimization measures.First of all,this paper takes the Wuhan Baishazhou Bridge as the engineering background,uses the finite element software Abaqus to to establish a three-dimensional model to analyze the most unfavorable load position of the pavement structure under the two loading modes of ultimate failure and fatigue failure comparatively.The influence of load,temperature as well as pavement thickness on the mechanical response of pavement structure is also concerned.The result shows that the increase of load and temperature will have an adverse effect on the stress of the pavement structure while the increase of the thickness of the pavement layer will have a favorable effect;the maximum tensile stress and strain of the bottom of the pavement layer appear near the diaphragm while the maximum shear stress of the waterproof adhesive layer appears near the edge of the longitudinal stiffener.The shear stress of waterproof adhesive layer at 25 ? is the largest,which shows that if the ultimate shear stress is taken as the design standard,it is reasonable to use the shear strength at 25 ? as the index.Secondly,the fatigue tests of epoxy resin waterproof adhesive layer and SMA pavement material were carried out respectively.The self-developed direct shear fatigue device was used to carry out fatigue tests on waterproof adhesive layer,and the change rule of shear fatigue life of waterproof adhesive layer under different temperature,stress and coating dosage was studied.Four point bending fatigue test was used to analyze the effect of temperature and strain on SMA pavement materials,and two corresponding fatigue life prediction models were established.The results show that stress,temperature and coating amount all have significant influence on the shear fatigue life of the waterproof adhesive layer,among which stress has the greatest influence;with 25? as the boundary,the shear fatigue life decay rate of the waterproof adhesive layer increases significantly with the increase of stress.The bonding performance between the waterproof adhesive layer and the SMA pavement layer is the key to affect the shear fatigue life of the interlayer.Temperature and strain have a significant effect on the bending fatigue life of SMA pavement material,and temperature has a greater impact.Finally,contrary to the three main diseases of rutting,cracks and delamination problem in the Baishazhou Bridge in Wuhan,the fatigue damage of pavement structure under the combined action of vehicle and temperature was analyzed based on the mechanical analysis results and the fatigue life prediction model of the waterproof adhesive layer and the SMA pavement layer.Based on Miner's fatigue damage theory,the service life of the pavement structure of Baishazhou bridge under the existing traffic volume and environmental conditions was calculated,the causes of the early diseases of the pavement structure were revealed,and the corresponding optimization measures were proposed.The results show that the fatigue life of pavement structure calculated by rutting deformation,bending tension fatigue failure at the bottom of pavement and shear fatigue failure between waterproof bond layers is 6 years and 10 months,10 years and 8 months,and 2 years and 9 months,respectively,which can not meet the minimum service life requirement of 15 years for steel deck pavement structure,indicating that more attention should be paid to the fatigue damage caused by various fatigue damage in the design of steel deck pavement structure.The ultimate failure of pavement structure can not be considered only,and the interlaminar shear fatigue failure with the shortest fatigue life should be considered more importantly.Increasing the thickness of the pavement layer and restricting the traffic volume are currently more effective measures to extend the service life of the Baishazhou Bridge pavement structure,which can increase the service life from the original 2 years and 9 months to 6 years.