Abstract
Seismic pounding phenomena, particularly the collision of neighboring buildings under long- period ground motion, are becoming a signifi-cant issue in Japan. We focused on a specific apartment structure called the Nuevo Leon buildings in the Tlatelolco district of Mexico City, which consisted of three similar buildings built consecutively with narrow expansion joints be-tween the buildings. Two out of the three build-ings collapsed completely in the 1985 Mexican earthquake. Using a finite element code based on the adaptively shifted integration (ASI)-Gauss technique, a seismic pounding analysis is per-formed on a simulated model of the Nuevo Leon buildings to understand the impact and collapse behavior of structures built near each other. The numerical code used in the analysis provides a higher computational efficiency than the con-ventional code for this type of problem and en-ables us to address dynamic behavior with strong nonlinearities, including phenomena such as member fracture and elemental contact. Con- tact release and re-contact algorithms are de-veloped and implemented in the code to under-stand the complex behaviors of structural mem- bers during seismic pounding and the collapse sequence. According to the numerical results, the collision of the buildings may be a result of the difference of natural periods between the neighboring buildings. This difference was de-tected in similar buildings from the damages caused by previous earthquakes. By setting the natural period of the north building to be 25% longer than the other periods, the ground mo-tion, which had a relatively long period of 2 s, first caused the collision between the north and the center buildings. This collision eventually led to the collapse of the center building, fol-lowed by the destruction of the north building.