藤本 真明 (Masaaki FUJIMOTO)
The redundancy of bridges is getting much attention because of the accidents of bridges such as the collapse of I-35W bridge in recent years. When a member of a steel truss bridge breaks, the impact is caused.For evaluating redundancy of the bridge with consideration of the impact, the dynamic nonlinear analysis is regarded as the most accurate. However, dynamic nonlinear analysis needs a huge computational cost. In order to reduce the computational cost, static analysis with dynamic amplification factor is widely used. Although 1.854 obtained for the single degree of freedom elastic system is generally used as the amplification factor, unnecessarily expensive by the amplification factor due to the neglect of plastic dissipation.In order to overcome the problem of the amplification factor, the redundancy evaluation based on the balance of works by gravity and inertia force, which uses nonlinear static analysis considering the dynamic effect as inertia force, has been proposed. However, the feasibility of the redundancy evaluation has been studied only for a simple mass point system. Therefore, we develop the redundancy evaluation so as to be applicable to the three-dimensional model of steel truss bridges with live loads.
Key Words : steel truss bridge, redundancy, nonlinear static finite element analysis, dynamic effect