Analysis Of Dynamic Response Of Girder Bridge Under Moving Vehicle

Dynamic response of bridge structures are an important subject of the bridge research field. Predecessors have affirmed through both theoretics and practices that the vehicle moving loads would lead to more deformations and stresses for bridge structures than the equivalent static loads. With the fast development of new technology and new material, bridge structures have inclined to be more light and gentle, so its dynamic problem should not be ignored when subjected to vehicle moving loads.In this dissertation, an element of vehicle-bridge coupling for truck-bridge interaction is established considering vehicle-bridge displacement connection. A vehicle of truck is modeled as an element possessing 2 axles and 4 degrees of freedom which is more coincident with the actual. ,and the bridge is modeled as beam elements. The equations of motion for vehicle-bridge whole system are formed using conventional finite element method, and they are solved using Wilson-θ method. This idea can be used for truck-bridge vibration analysis of bridge with various types. Based on the present method, a program computing dynamic response of bridge under moving truck is developed.The vibration properties of two existing bridges, a simply supported beam bridge and a continuous beam bridge, are analysised by the using of the all-purpose software ANSYS. Simultaneously, the vibration properties of the two bridges are also tested in locale.An example, in which dynamic responses and impact factors of simply supported beam are investigated with various height of dilatation joint and speed of truck, is given. The impact factors of continues beam are investigated with determinate function of uneven bridge, and compared with testing result.By setting certain components zero, the vehicle model with 4 degrees of freedom is degenerated to various simplified models such as moving forces model, moving masses model and moving periodic load model. Through the analysis of two examples, the impact factors of both simply supported beam and continuous beam with various models of vehicle and various speed of truck are evaluated and compared.