Research On Fatigue Performance Of Innovative High-resistance Steel Bridge Deck

Orthotropic steel bridge decks have a complex geometric structure and a large number of vertical and horizontal welds,leading to stress concentration in local structural details,and the problem of fatigue cracking is prominent under the reciprocating action of the vehicle’s wheel load.The development of orthotropic steel bridge deck with high fatigue resistance has important theoretical significance and engineering application value.In this paper,a new type of high-resistance steel bridge deck is proposed based on the new double-sided welded structure of the rib-to-deck details by introducing the new opening structure details of the transverse diaphragm.The nominal stress method and the equivalent structural stress method are used for the new high-resistance steel bridge.The panel is optimized for fatigue design and fatigue performance evaluation.On this basis,the rib-to-diaphragm details of the new highresistance steel bridge panel are analyzed for assembly error,and reasonable manufacturing parameters are determined.The main research results and conclusions are as follows:(1)This review summarizes the development history of orthotropic steel bridge decks,expounds the common fatigue cracking problems of orthotropic steel decks,and analyzes and summarizes the existing research methods to improve the fatigue performance of two typical fatigue vulnerable details of steel bridge decks.According to the rib-to-diaphragm details,a new design idea of the opening of the diaphragm is proposed.(2)According to the design ideas of the new opening of the diaphragm,the new opening structure details of the diaphragm are designed for the three common longitudinal ribs at home and abroad,and through the establishment of a finite element model,an in-depth and systematic theoretical study of the force characteristics of the new opening structure of the ribto-diaphragm details shows that the stress level at the arc-shaped opening of the diaphragm is relatively high.On this basis,the infinite life design method is used to optimize the design of the arc-shaped opening size parameters of the diaphragm,and finally reasonable and feasible design parameters are determined so that the arc-shaped opening of the diaphragm does not undergo fatigue damage.(3)In order to highlight the design advantages of the new type of openings in the diaphragm,three different finite element models were established for each of the above longitudinal ribs according to the opening form of the diaphragm(traditional opening of the diaphragm,no opening in the diaphragm,new opening of diaphragm),and then based on the equivalent structural stress method,the influence surface analysis is carried out for each fatigue failure mode of the two typical fatigue vulnerable details of the steel bridge deck,and the force characteristics of each fatigue vulnerable part are clarified.(4)The new openings of the diaphragm put forward higher requirements for the assembly of the longitudinal ribs and the diaphragm.The assembly accuracy is the main factor affecting the fatigue performance of the new opening structure of the rib-to-diaphragm details.Based on this,two new high-resistance steel bridge decks with better fatigue performance are selected for assembly error analysis for the rib-to-diaphragm details.The effect of the initial manufacturing error on the fatigue performance of the new type of steel bridge deck was quantified by the equivalent structural stress method,and a reasonable assembly accuracy was determined to provide new theoretical and technical support for the factory to manufacture orthotropic steel bridge decks with the new type of structural details.