Performance of bridges with seismic isolation bearings during the Maule earthquake, Chile

摘要

On February 27, 2010 an earthquake of magnitude M_w=8.8, with epicenter in Cobquecura, Maule region, hit the central part of Chile. After the earthquake, a tsunami occurred that caused heavy casualties and damage to buildings and infrastructure. In particular, 4.5% of the overpasses located in the affected region suffered some type of damage and 25 bridges and several pedestrian bridges collapsed. At that time, there were about a dozen bridges with seismic isolation bearings in Chile, two of which were instrumented with accelerometer networks: the Marga Marga Bridge, located in Vina del Mar, and an elevated section of the Metro Line 5 in Santiago, at approximately 300 km and 400 km from the epicenter, respectively. This paper analyzes the acceleration records obtained at these instrumented structures and studies the effect of the seismic isolation on their dynamic response. The beneficial effect of the isolation system, especially in the longitudinal direction, is apparent. In addition, some flaws in the collapsed bridges are described.