Preliminary numerical study on the reduction of seismic pounding damage to buildings with expanded polystyrene blocks

Collisions between neighboring buildings during earthquakes cause a direct impact force on the buildings. These collisions exhibit characteristics that differ considerably from the vibrations caused by the seismic excitation. This seismic pounding phenomenon may cause severe damage to structural and nonstructural components and may induce fatal collapse of the building itself, even if its seismic resistance is ensured. Installation of shock-absorbing materials on the walls of neighboring buildings has been proposed to reduce such damage; however, the reduction effect on impact has not been verified, and the practical experiments required observing this effect entail high costs. This study aims to verify the damage reduction effects of shock-absorbing materials placed between two neighboring buildings through seismic response analyses using a finite element code based on the adaptively shifted integration–Gauss technique. As a shock-absorbing material, we focused on expanded polystyrene (EPS) blocks that can be designed in any size and with various rigidities. Because EPS materials have nonlinear compression properties that differ significantly from those of metallic materials, a database reference algorithm that numerically reproduces these properties was devised and implemented in the numerical code. The results of a preliminary simulation of a single case revealed that when EPS blocks were installed, the peak of acceleration at the time of collision and the ratio of yielded members to all structural members were reduced in both neighboring buildings. The most appropriate foaming ratio and thickness of the EPS blocks were also discussed.