Analysis On Design Of Truss-String Structure Applied In Superstructure Of Overbridge

The paper combines bridge engineering with the characteristic of truss-string structures, adopts truss-string in the superstructure of one overbridge as major load-carrying members, and analyses the platform bridge structure in five facets as follows:(1) Through static structural analysis of the overbridge, it is all defined including the dimensions of the member cross-section, the initial tensioning force of bridges cable and the construction process. Considering huger service loads, the flexibility of the truss is an important factor when the initial tensioning force is defined. In this structure, the bottom chord cable and the suspender are directly combined and intersect in the same plane. Particular nodes which are at the points the cable and the suspender intersect are designed to avoid the influence of contacting with each other.(2) The analysis of the bridge structural response under the pedestrian excitation. The frequency of pedestrian excitation is from 1.8Hz to 2.5Hz.We find the triaxial FEM calculation model,calculate the frequency of the platform bridge,observe its mode shape,simulate the vertical and horizontal pedestrian excitations, analyse the bridge structural response under the pedestrian excitation and adopt measures to reduce the resonance which is caused under the pedestrian excitation.(3) We adopt the numerical analysis method to simulate the time history of the wind speeds, transform the the time history of the wind speeds to wind pressures,analyse the structural wind-induced vibration response ,then acquire the structural stress and displacement and calculate the wind vibration coefficient.(4) The seismic response is calculated by seismic response spectrum method and input the acceleration time history of tianjin wave, El-centro wave and Taft wave to calculate the seismic response.(5) This paper numerically simulates the process that the platform bridge is built, calculates final forces and displacements of the structure, and contrasts this method with the conventional ones.