| Box girder bridge with corrugated steel-webs can greatly combine concrete and steel and bring the compression resistance capability of concrete and shear behavior of steel webs into full paly,which is a major improvement in the bridge construction industry.With the rapid development of box girder bridge with corrugated steel-webs in China,the normalization of the cross-section parameters and the design of the shear bonds and their fatigue performances are urgent issues that needed to be solved.Based on the 30 m corrugated steel-webs box girder bridge with double-box single-chamber,the finite element models are built by repeatedly changing the cross-section parameters,and the parameters are optimized and analyzed.Using the bridge shear key as the prototype,five push-out test models were designed to study their fatigue performances.The main research contents and achievements are as follows:(1)The longitudinal equivalent elastic modulus and the thickness of the equivalent straight steel plate of corrugated steel web are solved by means of unit load method of structural mechanics.The calculation formula of single chamber shear flow of corrugated steel web box girder is deduced by the structural mechanic of thin-walled bar.It is proved that the shear stress in corrugated steel web is uniformly distributed along the vertical direction,and the concrete roof and floor plate bear a considerable part of total shear stress.According to the theory of elementary beam,the deflection formula of corrugated steel web box girder under arbitrary concentrated load with the consideration of its shear deformation is obtained.The correctness of the theoretical formula is proved by comparison with the existing literature.(2)The problem of node coupling,grid size division and externally pre-stress simulation during modeling process are introduced in detail.The bending,shear and torsional properties of the composite box girder bridge are analyzed by repeated modeling with the thickness of the web,the length of the horizontal pane,the configuration angle,the thickness ratio of the concrete floor and the floor.The specific optimization values of each parameter are determined.(3)The basic theory of fatigue analysis is introduced,and the method of determining the fatigue load amplitude of the shear bond is summarized,namely the analysis of the most unfavorable section,the simulation of fatigue stress processing and ultimate capacity analysis.On the basis of these analysis,the push-out tests of Twin-PBL shear bond and associated static load experiment and fatigue experimental scheme are designed.(4)The static load characteristics and fatigue properties of the shear bond are analyzed by finite element simulation.The simulation results are in good agreement with the experimental results,and the accuracy of the finite element method and the experimental scheme are verified.The static and fatigue failure mode of the Twin-PBL shear bond is determined and the fatigue life formula of the shear bond is fitted,which can provide a reference for the study of anti-fatigue performance of Twin-PBL shear bond. |
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