Upgrade Decision-Making for Earthquake-Vulnerable Wooden Houses Using Probabilistic Damage Index Functions

Abstract

There is widespread awareness in seismic-prone countries of the necessity to improve the seismic performance of old buildings and houses for disaster mitigation. To support the decision making of house owners regarding upgrades, appropriate seismic risk information should be conveyed to them; such information would allow them to compare the effects of seismic upgrade strategies on risk reduction. This study develops probabilistic damage index functions for wooden houses in Japan, taking site conditions into account. Three existing 2-story wooden houses with traditional seismic resistance elements typical of 1960s and 1970s construction are virtually upgraded or downgraded by adding or removing walls and/or braces to model houses with a range of load-carrying capacities. Then time history analyses are conducted by using simulated ground motions and the maximum interstory drift ratio to develop the damage index functions. Finally, the validity of the proposed functions is demonstrated by using field survey results.