Effect of Temperature Changes on the Experimental Modal Analysis of a Galvanized Steel Benchmark Structure

The effect of temperature change on modal frequencies leads to erroneous results in the detection of structural damage. Therefore, quantifying the temperature dependency of modal frequencies is essential to improve the reliability of damage identification. Due to the irregular and time-dependent nature of temperature distribution, reliable correlations between air or surface temperatures and modal frequencies cannot be established. In this study, the dynamic behavior of a galvanized steel benchmark structure was investigated at two controlled temperature levels (2 °C and 32 °C) using experimental modal analysis (EMA). The structure was excited using a shaking table, while ambient vibration signals recorded at ground level were used as pre-recorded excitation input to the shaking table. Modal parameters were identified using Enhanced Frequency Domain Decomposition (EFDD). The results showed that mode shapes remained consistent across temperature levels, whereas natural frequencies decreased by an average of 2.43%. The identified dynamic parameters exhibited an approximately linear trend with temperature change. These findings highlight the importance of considering temperature effects in experimental modal analysis of galvanized steel structures to avoid false damage detection.