Statistical analysis of underpasses damaged during 2010 Chile earthquake

Abstract

Approximately 300 bridges, representing less than 3% of the total number of Chileanbridges, were damaged during the 2010 Maule earthquake. From these damaged bridges, whichinclude pedestrian bridges, 20 suffered collapsed spans. The objective of this study is to conduct astatistical analysis of the 88 underpasses located in a representative section of the main route 5.This analysis is aimed to correlate the bridge characteristics with the observed damage level. Paststudies reveal that this type of post-earthquake analysis is a robust tool to nurture the decisionmakingprocess for upgrading vulnerable structures and for guiding future performance basedengineering studies. To conduct the statistical analysis a database was built with the underpassescharacteristics such as location, presence or absence of reinforced concrete (RC) stoppers orconcrete lids, skew angle, and seismic zone. Additionally, the database includes the description ofdamage, the required repairing action, and the estimated repairing cost. From this study it isconcluded that critical variables affecting the underpasses behaviour are the presence or absence ofstoppers, the skew angle, and the location of the bridge. Bridges with concrete lids should beavoided because their repairing cost is higher than the repairing cost of bridges with RC stoppersand have a larger probability of collapse The average repairing cost for the considered underpassesis estimated in 11% of their construction cost and the skewed underpasses were more vulnerablethan non skewed bridges because their repairing cost is higher.