The Research For The Calculating Theory Of Through Steel Truss Composite Bridge And Its Application

Through steel truss composite bridge is a new-type bridge structure, in which the deck slab is combined with longitudinal and transverse girder or lower chord so that they act together. Because of the advantage of big stiffness, low architecture height, low noise and vibration in train driving, well dynamic behavior and so on, this bridge structure is one of the ideal structure types in the bridge at high-speed railways. Along with rapid construction of high-speed railways and increasing speed of the using railways, through steel truss composite bridge will be widely used in China.The research about through steel truss composite bridge is still in its beginning stage in China. Although many through steel truss composite bridges were built at high-speed railways in Japan, France and so on, little literature was published. Therefore, the paper studies the computing theory of through steel truss composite bridge and its application elaborately. The main creating research works are as follows:1. By making through steel truss composite bridge to continuous structure equivalently, the approximate analytic solutions of through steel truss composite bridge under double-track symmetrical loads and double-track unsymmetrical loads are deduced. When through steel truss composite bridge is in the action of single-track loads, the responses of the structure could be obtained by adding two approximate analytic solutions above. Besides, According to displacement variation method and displacement function, the temperature responses of through steel truss composite bridge for taking the relative slip between steel girder and slab as well as shear lap in slab into account are acquired2. Aiming at the combing condition of longitudinal girder, transverse girder with concrete slab in bridge deck of through steel truss composite bridge, 3 types of space nonlinear slab-girder elements are put forward as follows: the 1st one is the slab-girder element in which the action between slab and girder together is considered, the 2nd one is the slab-girder element in which the vertical displacement of slab and girder is equal, the 3rd one is the transition slab-girder element. Displacementmode, rigidity matrix and computing-formulas of equivalent node loads of each type element are put forward.3. The rigidity matrix and the minifying method to equivalent node loads in the slab-girder element in which material nonlinearity and crack of concrete can be taken into account are given by means of layering slab-girder element.4. According to the slab-girder element above, the space nonlinear finite element method to through steel truss composite bridge is put forward. Its box figure is given and its program is made.5. A through steel truss composite bridge model with simple supportion is designed and fabricated. The model tests of many loading cases are carried out. The approximate analytic solutions and the numeric solutions of this paper fit in well with the results of the test, which explain the correctness of the paper's theory.6. Utilizing the space nonlinear finite element method of through steel truss composite bridge put forward in this paper, a 64-meter through steel truss composite bridge with simple supportion, which is to be constructed in Peging-Shanghai high-speed railway, is detailedly calculated. Responses of the structure under 2 kinds of collective effects of loads are obtained. The 1st one is the lst-stage dead load, the 2nd-stage dead load and live load (including double-track symmetry loads and single-track loads), and the 2nd one is the lst-stage dead load, the 2nd-stage dead load and variety of temperature. Some available conclusions are obtained, which can be referred to the design of through steel truss composite bridge.