The December 2004 Indian Ocean tsunami caused human loss and devastating damage to civil engineering structures along the west coast of southern Thailand. This damage was investigated to evaluate the vulnerability of structures. Criteria for post-tsunami investigation were developed, and a database system was established to manage and present the data. The database of reinforced concrete (RC) buildings was then analyzed to find the relationship between the damage level and (a) the distance from the shoreline or (b) the inundation height. A representative RC column's capacity to resist lateral forces was measured by a full-scale loading test to gain insight into the relationship between the observed damage and the actual structural performance.