Application Of Epoxy Resin Asphalt In Steel Box Girder Deck Pavement Of Double Tower Asymmetric Cablestayed Bridge

The deck pavement plays a significant role in the construction of large-span cable-stayed bridges with steel box girder,which has been the focus of research at home and abroad.However,from the perspective of the steel bridge deck pavement that has been opened to traffic,it can be seen that China’s construction of steel bridge deck pavement differs greatly compared to foreign technology,and its pavement layer have more problems.Domestic traffic composition is extremely complex with heavy,overloaded vehicles accounted for a high proportion.Therefore,in order to ensure the quality and service life of long-span steel bridge deck,the following researches including its deck pavement material performance,the structural suitability,convenience and economy efficiency of construction need to be further done.On the basis of analysing the research status of long-span steel bridge deck pavement design and epoxy resin asphalt pavement at home and abroad,the causes of various problems were studied and analysed in this paper especially by investigating the climatic conditions,structural forms and problems types of four bridges across the Yangtze River with epoxy resin asphalt pavement in Hubei Province,and the design and implementation schemes of bridge deck pavement structure layer of Shishou Yangtze River Bridge were then proposed;The finite element software was used to analyse the mechanics of the bridge deck,and the results of the on-site inspection of the bridge were combined to analyse the performance of the pavement application and the current situation after the bridge was opened to traffic.The conclusions were as follows:(1)Through investigating and studying the steel deck pavement of four bridges across the Yangtze River in Hubei Province where epoxy resin asphalt is used,the causes of various bridge deck defects were analysed and the deck pavement structure and pavement scheme were summarised according to the structural characteristics of the asymmetric double-towered cablestayed bridge with steel box girders at Shishou Yangtze River Bridge.The carriageway deck uses a double layer of lower EA + upper modified SMA double layer pavement,which can be adapted to its structural characteristics,traffic conditions,climatic features and functional requirements.(2)The pavement of the Shishou Yangtze River Bridge was under Abaqus finite element analysis,and through determining that most unfavorable load position of pavement and analyzing the stress of pavement under varied thickness,elastic modulus and vehicle forces,to further verify the application performance of epoxy resin asphalt in steel bridge deck pavement process;Finite element analysis showed that the worst load locations for the pavement were the centre of the stiffening ribs under the function of lateral load and the furthest end of the single diaphragm plate under the function of longitudinal load,which suggested that when designing the upper and lower pavements,try to avoid applying excessive load to these positions.The change of pavement thickness has no obvious effect on tensile stress,while the overall change of thickness will significantly increase the shearing stress,therefore it is recommended to limit the thickness to 60-70 mm;The change of elastic modulus of pavement has a positive gain relationship with tensile stress and shearing stress,and a negative gain relationship with vertical displacement.The elastic modulus of upper layer was 1000～1500MPa,and the elastic modulus of lower layer was1600～2100MPa.From the perspective of vertical displacement and tensile stress,the increase of vehicle load has a greater impact on the upper pavement,but from the perspective of equivalent stress and shearing stress,the increase of vehicle load has a greater impact on the lower pavement.(3)The material source of EA10 epoxy resin asphalt mixture is very critical,and its epoxy resin binder and waterproof adhesive layer have higher requirements.The construction of mixture should be based on the best construction mix ratio determined by the target mix ratio.When paving,it should be “no water source”.The paving should be done at one time according to half full section.When rolling,the initial pressure temperature should be≥155℃,the recompression temperature should be≥110℃ and the final pressure temperature should be≥90℃.4)Inspection and test verification indicated that in measuring flatness and thickness,the results met the requirements of design and relevant specifications,and epoxy resin asphalt pavement had good road performance,which was suitable for steel bridge deck pavement in high temperature environment for a long time.Through more than two years’ operation,it was shown that the deck of Shishou Yangtze River Bridge,adopting the lower EA10 double-deck pavement,could meet its structural characteristics,traffic conditions,climate features and functional requirements.The long-term road performance of the pavement structure under the conditions of asymmetric structure,traffic volume and temperature of the bridge remains to be tested by time.