MACHINE VISION DAMAGE DETECTION OF RC COLUMNS FOR RAPID POST-EARTHQUAKE SAFETY ASSESSMENT S. German, I. Brilakis and R. DesRoches Department of Civil Engineering, Georgia Institute of Technology 790 Atlantic Drive NW, Atlanta, GA 30332, USA ABSTRACT Post-earthquake inspection of structures relies heavily on certified inspectors to make an assessment of the existing state of the structure based primarily on qualitative measures. To accelerate post-earthquake recovery, these inspections must be completed as quickly as possible. Thus, a machine vision based assessment procedure is proposed that offers a cost-effective, rapid and quantitative approach to assessing the condition of a building following an earthquake. The method outlined in this work focuses on reinforced concrete (RC) frame buildings, with specific attention to the assessment of the damage state of RC columns as these are the critical member with respect to maintaining gravity load carrying capacity. This procedure relies on established relationships between the visible damage, and the response mechanisms exhibited by the structure. The method in automated retrieval of critical damage properties is validated using image data of RC columns acquired after the 2010 earthquake in Haiti. The damage state of the columns, and the entire structure, is then constituted using these critical damage properties. Keywords: Machine-vision, reinforced concrete, damage detection, post-earthquake, safety assessment 1. INTRODUCTION After an earthquake occurs, entry into damaged buildings as soon as possible is necessary for a variety of reasons, including emergency search and rescue, building stabilization and repair and salvage and retrieval of possessions (ATC (1999)). There are always extensive risks associated with entering damaged buildings after an earthquake. Currently, the safety of entering damaged buildings is evaluated manually by structural engineers and/or certified inspectors. They follow guidelines provided by government authorities such as the Federal Emergency Management Agency (FEMA) and the Applied Technology Council (ATC), and assess the impact of visual damage on critical structural components (e.g. reinforced concrete columns) to discern the existing stability of the structure. Although civil engineers are the appropriate candidates to evaluate the safety of highly engineered environments (Prieto (2002)), several limitations were found in the current evaluation processes. First, it is time-consuming. Collaboration-related problems between civil engineers and other organizations involved in disaster relief efforts have been recognized as attributable, including the lack of coordination, information sharing, trust and communication (Kostoulas et al. (2006)). Typically, it is the role of government authorities to fuel the system of relief and recovery in the aftermath of an earthquake; however, government bureaucracies are ill-suited to the pace and demands associated with these processes (Olshansky and Etienne (2011)). These issues can be highlighted in the events following the October 15, 2006 Hawaii Earthquake and the December 22, 2003 San Simeon Earthquake. In each of these cases, the building safety evaluation processes took several weeks to complete due to the large