Dynamic Characteristics And Adaptability Analysis In Railway Of A New Type Of Steel Truss Composite Bridge

ABSTRACT:With the development of China railway and increasing train speed, some new types of composite bridge structures have appeared in the newly-constructed railway lines, including heavy haul railways, passenger railways and high-speed railways. A new type of through girder-steel truss composite structure is adopted for the main bridge of Zhenbeilu Overpass, which is located on the Guangzhou-foshan railway line. This structure is composed of a triangular truss and a concrete through girder. Compared with the traditional railway through steel truss bridge, it has lower cost and larger stiffness, moreover, it has the characteristics of more reasonable force and convenient construction. This paper studies the dynamic performance of this new type of composite bridge structure, which can provide reference basis for its application on heavy haul railways, passenger railways and high-speed railways in our country. The main contents are as follows:(1) A3-D finite element model of Zhenbeilu Overpass Bridge is established with the help of ANSYS. The natural frequencies and modes of the bridge are obtained by modal analysis.(2) The heavy haul freight train, medium-speed passenger train and high-speed passenger train loads are simplified as a series of moving concentrated forces which are ranged according to the actual wheelbase. Dynamic responses of the bridge under different train speeds are calculated and the bridge resonance is discussed.(3) The heavy haul freight train, medium-speed passenger train and high-speed passenger train loads are simplified as moving wheels and sprung masses. Dynamic responses of the bridge are calculated by taking the track irregularity into consideration, and compared with the results obtained above. The error of the two vehicle models is thus analyzed.