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Dynamic Response Analysis of Overpass Bridge under Superelevation Vehicles’ Collision

Author: MaXiangLu
Tutor: ZuoLuKuan
School: Beijing University of Technology
Course: Bridge and Tunnel Engineering
Keywords: overpass bridge superelevation vehicles collision dynamic response nonlinear
CLC: U448.27
Type: Master's thesis
Year: 2009
Downloads: 146
Quote: 5
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Abstract

With the rapid development of economic construction, a large number of over-cross structures have become the main way of relieving the traffic pressure, such as building overpass. However, it is of common occurrence that collision occurred between superelevation vehicles and overpass bridges because of bridge clearance limitation or driving in the wrong way. Although, the probability of the collision, between superelevation vehicles and overpass bridges, is not high. Once that happens, it will result the damage of the bridge and affect its structure performance and using performance, seriously losing using function. Therefore, what is provided a scientific basis is how to evaluate the impact of superelevation vehicles on the bridges scientifically. Meanwhile, it is of great practical significance and application value for the design, operation and maintenance management of the bridge.The collision between bridges and vehicles is a very complicated process. The damage of bridges by the impact, not only depends on the structural characteristics of the bridge itself, but also depends largely on the speed of objects, quality, stiffness, impact position, impact angle and load objects connected with the car and so on. In this paper, through investigation analysis of vehicles’accidents, Prestressed Simple Supported T Beams is impacted, using the heavy-duty trucks containing standard containers for the impact vehicle on the basis of a large number of data collected about vehicles and containers. Numerical simulation analysis is carried out on the collision between bridges and vehicles under the different working conditions, in addition of the impact status.In order to study on the stress of bridges under superelevation vehicles’collision and make further research for the collision mechanisms of vehicle-bridge, a simulation analysis is conducted to the procedure of collision with abaqus which is a general and infinite element program. There were several conclusions from these researches:(1) Different speeds: the faster the speed is, the greater stress and displacement the main girder has; and the shorter time the girder reaches the maximum stress and displacement; in addition, the greater range it damages.(2) Different quality: the larger the quality is, the greater trend the stress and displacement of the main girder increases. The bridge’s damage causes by increased quality depends on stiffness of the impact object. The bigger the stiffness is, the more significant the effect induces by quality. The increase of quality will not cause that of bridge’s damage when the rigidity is small to a certain extent.(3) Different angle: the larger the angle is, the small stress and displacement the main beam has. It will probably be inclined to a more serious damage when impact on some angles for a local area of bridges. (4) Different heights: the smaller contact height is, the more serious the local destruction is. Furthermore, the greater contact height is, the bigger trend the stress and displacement of the bridge overall increases.(5) Different connection status: for the stress and displacement of main girder, consolidation connection has maximum value, and frictional connection has minimum value, whereas the value of articulated connection lays both two situations. Namely, the better the integral performance between containers and vehicle, the more serious the destruction of the bridge is. When connect frictional, starting time of girder rebound is the earliest, and energy losing is the largest. In the system of frictional connection, elastic strain energy and plastic strain energy is smaller than other two situations, so the influence of the bridge structure is less relatively.(6) For the situations above, the main girder with a diaphragm plate in the middle span, has larger stress and smaller displacement, compared with that without diaphragm. Visible for the collision, if impact location of the girder increased, its force state will be greatly improved.(7) The transformation relationship of system’s energy: kinetic energy of vehicles largely transform to plastic strain energy of system, which of a small part to elastic strain energy ,besides extremely little part dissipated through friction. So, the energy of vehicles is absorbed by plastic deformation of containers. This shows what also the important factor of bridge damaging is stiffness and deformation capacity of impact objects.(8) With diaphragm, the damage forms of concrete dominate on uniaxial compressive failure in diaphragm plate. Whereas, the form without diaphragm mainly on T beams’juncture unit of web and flange tension-destroying.

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