Influence Analysis Of Dynamic Mechanics For Bridge With Multiply Point Input Of Earthquake

Long-span bridges are an integral and important part of country transportation.Nowadays, it is pursuing core objective for many scholars to be in seismic areas of research bridge structures and to find more effective ways to resist the seismic action on the bridge structure damage. Long-span bridge structure is often more intensive vehicle traffic public places which Seismic safety performance can not easily be ignored. For long-span bridge has a large-span feature, calculation method research of bridge seismic areas is much more complex than ordinary bridge structures and the factors need to be taken into account are much more. It is for traditional analytical methods of large-span structure seismic response to ignore range of ground motion in space and considered when the earthquake occurred different fulcrum surface movement of long-span bridges are the same. However, long-span bridge structure extends longer and the altitude difference of different pier abutments is relatively large that the data obtained of consistent point input of earthquake does not comply with the real situation. Therefore, it has a great theoretical significance and a great value of engineering studies to research the dynamic response of multiply point input of earthquake.A numerical model was established for the three-span girders bridge with multiply point Input of earthquake waves.It started from Lagrange equation in dynamic mechanics.The procedure for its numerical solution was presented with Longe-Kuta method. It can draw the same conclusion by comparison with the results of the dynamic response of a bridge model which is under three seismic waves. For long-span bridges, relative displacement with multiply point Input of earthquake is bigger than the single point input of earthquake. Value of increasing displacement coefficient reaches 4.96 at 0.1s timedelay. Beam quality, the bridge pier rigidity and equivalent damp coefficient have an effect on relative displacement between the pier and beam. It is very significant for the structure design of long-span bridge to consider the factors and to choose optimum combination in order to avoid falling beam damage.