3-Dimensional Analysis of Dynamic Behavior of Bearing of Nielsen Bridge

In 1995, the great Hanshin-Awaji earthquake caused a large amount of destruction and structural failures. One example, whose mechanism is not fully clear, is the fracture of a bridge bearing of a Nielsen type bridge that does not occur under the ordinary static or dynamic loading conditions. The fracture probably resulted from very high stress due to an unexpected dynamic mechanism. In this paper, the 3-dimensional dynamic behavior of a Nielsen type bridge was analyzed by assuming a collision between the upper and the lower parts of the bearing, which might have occurred in the great Hanshin-Awaji earthquake. The numerical results show that an impact due to a relative velocity of 5∼6m/s between the upper and the lower parts of the bearing generates a stress sufficient to cause a fracture in the upper bearing. The observed features of the actual fracture surface was also simulated fairly closely.