케이블 횡 진동 효과를 고려한 3차원 사장교의 동적거동 특성
(The) Effect of Lateral Cable-Vibration on 3-Dimensional Dynamic Responses of Cable-Stayed Bridges
케이블 횡진동 사장교 동적거동;
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The basic idea of cable-stayed girder bridges is the utilization of high strength cables to provide intermediate supports for the bridge girder so that the girder can span a much longer distance. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. A convenient method available at the present time to account for the cable sag and nonlinearity is the concept of a straight line chord member with a equivalent modulus of elasticity substituted for the actual cable member. Another nonlinear consideration is that of the behavior of the girder and tower when they are subjected to both compressive loads and bending. Structural members which carry both axial forces and bending moments are subjected to an interaction between these two effects. This is taken into consideration by using stability functions. Three characteristics which distinguish cable-stayed bridges from conventional girders or trusses of comparable span are their low weight, their increased flexibility, and their reduced ability to absorb energy by sliding friction between components. Therefore, recent structures are becoming more sensitive to not only static effects but dynamic effects as well. Techniques required for the static analysis of cable-stayed bridges has been developed by many researchers. However, little work has been done on the dynamic analysis of such structures. To investigate the characteristics of the dynamic response of long-span cable-stayed bridges, two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration( both in-plane and swinging ) on the overall bridge dynamics. A computer algorithm is developed to solve the nonlinear static, eigen problems. The result of this study demonstrated the importance of cable vibration on the overall bridge dynamics.