Dynamic Response Of Skew Simply Supperted Bridge Under Moving Loads

In the construction of the bridge, the skew bridge is frequently used by necessary of the terrain characteristics in the place, the alignment requirements in the standard, and the necessary of the space on highway road interchange. Actually, there must be some relationship and distinction between the square bridge and skew bridge. Although the skew bridge can better apply to route requirements, because of the antisymmetry of the shear force, under vertical load, the main girder bending effect will also produce torque, the main girder torsional load will also produce bending at the same time. So the feature under the stress on the skew is more complex than the square bridge. Up to now, the static behavior of all kinds of square bridge has been thoroughly studied. The fixed theory and effective calculation method is formed. But for the dynamical behavior on the skew bridge, the study is not meet for a satisfactory degree at home and abroad. So it is necessary to research the dynamic reaction on bridge undering the moving vehicle force.The simply supported girder bridge is taken as the engineering background on this paper. In the situation of the different skew angles and the different transverse position of vehicle load, the node dynamic load is used in the time history analysis. The vehicle load is accurately simulated as the whole process of the moving through the bridge. Considering when transverse different beams achieve to maximum dynamic deflection in the actual position of the vehicles are not the same. The time when maximun dynamic deflection is reached is obtained to analyse the impact of the simply supported beam on different skew angles. The main work includs:(1) The dynamic response of simple supported beam under the moving load is analyzed. The finite element analysis software MIDAS is used to simulate the process of when the uniform constant force moving through the simply supported beam. The first5natural frequencies of simply supported beam are obtained with the modal analysis and compared with the analytical solution. The dynamic displacement on each section changing with the time is compared with the analytical solution. The feasibility of the finite element method is verified. (2) Based on the above analysis, the three dimensional model is established by using the entity unit model, the vibration characteristics changing with the skew angle on the structure are find out. Consider in the horizontal cloth and the skew angle, the dynamic displacement of the mid-span on each beam is evaluated.(3) The maximum dynamic deflection is evaluated and is compared with the results of static analysis. The dynamic increment is also evaluated.(4) This paper summarizes the above research achievements and is puts forward the future research direction.