## 部材破断の動的効果を考慮した鋼トラス橋の耐荷力の数値的評価

Numerical Evaluation of Load Capacity of a Steel Truss Bridge with Considering Dynamic Effect of Member Failure
**塚田 健一** (Kenichi TSUKADA)

Since the accident of the I-35W Mississippi river bridge in 2007, the importance of redundancy of bridges has been recognized. In evaluating redundancy, progressive failure phenomena should be taken into account because failure of a member has an impact to the whole structure system. Generally, the impact, i.e., the dynamic effect is considered by employing the impact coefficient in static analysis. The impact coefficient by URS(=1.854) that is obtaind by the dynamic analysis of a single DOF system is widely used as far. However, since dynamic behavior of truss bridges is considerably more complex than that of single DOF system, the value of the impact coefficient (1.854) is still open to discussion. In order to investigate the impact effect, in this paper, dynamic behavior of a typical steel truss bridge arise from failure of a member is simulated by dynamic nonlinear analysis with a finite element model including gusset plate connections.

* Key Words* :
steel truss bridge, nonlinear dynamic finite element analysis, redundancy, impact coefficient, dynamic effect