| With the advantages of excellent mechanical properties,good economic durability and easy assembly construction,steel plate composite girder bridges have been gradually applied to curved sections or transition sections in mountainous areas,urban interchanges and other complex terrain areas in recent years.As the main load-bearing member of curved steel plate composite girders,the design of its reasonable spacing and structure is particularly important.Considering the lack of design methods for crossbeams of curved steel plate composite girder bridges in the current Chinese code,this paper studies the reasonable spacing of crossbeams from the perspective of steel girder strength design in the construction stage of curved steel plate composite girder bridge.The main research contents and conclusions are as follows:(1)The main construction methods of steel plate composite girder bridge are summarized.When the composite girder bridge are constructed in steps,the construction constant load is divided into vertical uniform load and external overhang load.Based on the results of finite element analysis,the stress distribution characteristics of curved steel girder structure under constant load during the construction stage are investigated.The results show that when the steel girder is subjected to torsional action,the force on the flange is manifested as bearing the axial force while bearing the lateral bending moment.(2)Based on the thin-walled curved rod theory and the method of "comparing the flange to a continuous beam",the force analysis model of the curved steel girder structure in the construction stage under vertical uniform distribution load and external overhang load is established,and the theoretical calculation method of steel girder stress is proposed.ABAQUS software was used to establish the slab-shell analysis model of steel girder structure in the construction stage and verify the theoretical calculation method.The results show that when the number of crossbeams n≥3,the theoretical calculation results are in good agreement with the finite element results,and the error is within 10%.(3)The theoretical calculation method of steel stress proposed in this paper is compared with the existing specifications and theoretical methods for calculating the flange stress of steel girder,including vertical uniform load and overhang load.The results show that for the vertical uniform load,the theoretical method in this paper is used to calculate the axial uniform stress of the flange of each main girder with high calculation accuracy,and the recommended method of the Japanese ’21 Design Data Book manual and the calculation method of the flange bending effect when the simplified coefficient specified in the American AASHTO code takes 10 can safely calculate the non-uniform stress caused by the lateral bending of the flange.For the lateral bending effect of flange under external overhang load,the calculation results of the American AASHTO code method are on the safe side.(4)Based on the stress calculation method and finite element method of curved steel girder structure proposed in this paper,the ratio of non-uniform stress to uniform stress of flange is defined as "warping stress ratio",the distribution law of warping stress ratio in steel bridge structure and the change law of the most unfavorable warping stress ratio are studied,and a simplified calculation formula of the most unfavorable warping stress ratio considering parameters such as flange width,girder height,span diameter,curve radius and crossbeam arrangement spacing is proposed.In the design,the maximum spacing of the crossbeams in the construction stage can be quickly estimated according to the limitation of the warping stress ratio of the steel girder flange.Compared with existing design cases,the method proposed in this paper is safe and feasible. |
PDF Full Text Request