The Dynamic Reliability Analysis Of Railway Large-span Steel-concrete Composite Truss Bridge

As a new bridge structure,the Long-span steel-concrete composite truss bridge has been increasingly developed in recent years.With its larger stiffness,Stronger spanning ability,and light figure,the Long-span steel-concrete composite truss bridge has significant advantages on the railroad underbridge that is limited by height and headroom beneath.At present,4bridges with 80m-span on Xian-Pingliang passenger dedicated line are the truss bridges with largest span,sophisticated design and the most difficult construction skill in the world.The structure composed of two pieces of triangular steel truss and a grooved concrete girder.The research in this essay is based on the construction of the four steel-concrete truss bridges,and the two-year initial static/dynamic loading test after these bridges putting into use from 2015 to 2016 With the background,this essay focuses on the dynamic reliability study of railway large-span steel-concrete composite truss bridge.The dynamic working condition of four 80m-span steel-concrete truss bridges in Xian-Pingliang railway is obtained by dynamic loading test.The field test data meet the limits required for railway bridge inspection and design specification.Then,The train-bridge time-varying system of steel-concrete composite truss is analysised and the train structural frame lateral acceleration crawl wave is simulated randomly and is used to excitate the railway bridge;the time-dependent characteristic of steel-concrete composite truss,as well as intensity and stiffness loss after joints,steel webs or overall damage,are all covered in this study.And This essay also derives a Quasi-Hamilton System which could apply on railway steel-concrete truss bridge according to the Hamilton Theory.With this system,we could analyze the dynamic reliability of railway steel-concrete truss bridge quasi-integrable and quasi non-integrable Hamilton system.The reliability function and possibility density function are shown by running a finite difference program in Matlab,and at the same time,we can get the function images.What's more,the influence of initial energy0 H ? critical energycH and bridge damage on reliability function are also discussed here.Through the deep analyses on images,this essay gives reasonable suggestions on bridge construction and operation.Finally,From the reliability study on the four bridges,the result illuminates that considering the nonlinear characteristic of steel-concrete truss bridge is favorable for the bridge dynamic reliability analysis.It is feasible to deduce the quasi-Hamiltonian system which is suitable for the railway steel-concrete composite truss girder bridge.It is feasible to deduce the damage of the bridge.