In-Service Condition Assessment of a Long-Span Suspension Bridge Using Temperature-Induced Strain Data

Monitoring data of civil structures mainly include load- and temperature-induced structural responses. Traditional damage-detection methods use vibration-based structure responses by eliminating temperature effects from the measured data. In this article, a new structural damage identification method using temperature-induced responses is proposed and applied to a long-span suspension bridge. The novelty of the method is that it derives the structural transfer function by taking temperature load variation and temperature-induced strains input-output data; thus, it is able to accurately reveal inherent structural characteristics, unlike traditional methods that use structural vibration responses from ambient testing. In the proposed method, the temperature-induced strain is separated from measured strain responses with ensemble empirical mode decomposition (EEMD) technology, and a Euclidean distance-based damage index is defined that uses temperature variations and temperature-induced strains for structural damage detection. Numerical analysis results successfully verify the feasibility of the proposed method, which was used to evaluate the condition of a long-span suspension bridge before and after a ship collision with the use of the monitoring data. The performance of the bridge under normal operating conditions was also evaluated through the proposed method with the use of long-term monitoring data, including temperatures and strains. (C) 2016 American Society of Civil Engineers.