Traditional methods of determining structural dynamic parameters produce destructive and unreliable results. Therefore, in this study, operational modal analysis method, which is a non-destructive and advanced method, was used to determine structural dynamic parameters. In this study, the dynamic parameters of the steel garage model were determined by the operational modal analysis (OMA), method and the current status of the structure was evaluated. The finite element model (FEM) of the steel garage was created with SAP2000 software, and then the experimental data were analyzed with Artemis Modal Pro software. When the FEM and OMA results were compared, it was seen that the frequency values obtained for the first five modes were quite close. When the damping ratios were examined, significant differences were detected between the theoretical and experimental values in some modes. It was determined that using the experimental damping ratios instead of the constant damping ratio assumed in the FEM would give more accurate results. Provided that the modeling and measurement stages are carried out meticulously, the operational modal analysis method as a non-destructive testing method is recommended to be used to obtain dynamic parameters in structures similar to the steel garage model.

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.

In recent years, the integration of nano titanium dioxide (TiO₂) into building materials has become a popular research topic due to its superior mechanical, photocatalytic and self-cleaning properties. In this study, the dynamic behavior of a light steel container house model coated with nano-TiO₂ is investigated using Operational Modal Analysis (OMA). The effects of TiO₂ on the natural frequencies, damping ratios and mode shapes of the light steel container house model are investigated. The Stochastic Subspace Identification-Unweighted Principal Component (SSI-UPC) method is used to extract the modal parameters from the ambient vibration data. The results show that the TiO₂ coating significantly increases the stiffness and improves the damping properties by increasing the natural frequencies of the light steel container house model. The findings indicate that nano-TiO₂ coatings can increase the structural integrity and durability of light steel container houses. This study provides a foundation for future research on nano-reinforced coatings in light steel structural systems.

The aim of this research is to determine the effect of nanocoating retrofitting on the dynamic responses of industrial steel chimneys. A 20 m high industrial steel chimney was selected for nanocoating retrofitting. First, a three-dimensional finite element model of the chimney was created, and modal analysis was performed in SAP2000 software, and frequency values and mode shapes were obtained. Later, linear analyses of the chimney were made using the 1995 Kobe earthquake ground motion recording. Then, the outer surface of the chimney was retrofitted with a 1 mm MgO nanocoating, and dynamic analyses were made. Finally, the chimney’s dynamic responses before and after the MgO retrofit, such as minimum–maximum von Mises stresses and displacements, were compared. At the end of the study, it was observed that the displacements along the chimney height, especially maximum displacements, decreased from 150 mm to 140 mm, and the minimum von Mises stress at the bottom of the chimney decreased from 37.20 kPa to 30.19 kPa, and the maximum von Mises stress from 1519.27 kPa to 1332.33 kPa stresses in the analyses results. The decrease in frequency values revealed that MgO nanocoating had a positive effect on the stiffness of the chimney. It can be understood from this study that nanocoatings will be very useful in retrofitting industrial steel chimneys and have an effect on dynamic parameters.

Seismic retrofitting is widely used to enhance the dynamic performance of steel structures. This study experimentally investigates the effect of seismic damper retrofitting on a scaled steel frame using ambient vibration testing. Both as-built and retrofitted configurations were evaluated under low-amplitude excitations generated on a shake table. Modal parameters, including natural frequencies, mode shapes, and damping ratios, were identified using output-only Operational Modal Analysis (OMA) based on the Enhanced Frequency Domain Decomposition (EFDD) method. The results show a significant increase in damping ratios, with more than a 23-fold improvement in the first mode, along with mode-dependent frequency variations ranging from 17.63% to 142.74%. Mode shape comparison confirms strong consistency between configurations. The findings indicate that the integration of the damping devices enhanced the overall energy dissipation capacity of the scaled steel frame by increasing its global damping ratios and modifying the modal responses. The results suggest that output-only OMA can provide valuable insights into damper effectiveness, offering a practical alternative when controlled input excitation is not available.

From past to present, building designs and materials used are developing. Especially against the destructive effects of ground movements and free vibrations on structures, many structural system designs and composite structure designs have been developed. The purpose of the composite structure design is to choose different types of materials according to the structural load-bearing system stress, in short, to choose the most advantageous material type according to the cross-sectional stresses or to eliminate the negative aspects of one material with the positive aspects of another material. It is a known fact that the dynamic performance of steel structure carrier systems is high under the influence of ground movements and free vibrations. However, in cases where the section geometry cannot be changed due to architectural concerns due to architectural design difficulties, there are cases where the rigidity of the structure is not sufficient. In such cases, profiles made of different materials other than steel can be used in order to increase the rigidity of the structure, especially in the columns, which are a very important component of the structural load-bearing elements. Therefore, in this study, the effect of using molybdenum profile instead of steel profile on modal parameters in model steel structure columns was investigated. In the light of the information obtained, a decrease of approximately 23.72 percent was observed in the period value in the 1st free vibration mode of the steel-molybdenum structure model. Thus, it is understood that the rigidity of the model steel structure system increases. In cases where it is not possible to change the architectural design in steel structures, it is recommended to use column profiles as molybdenum profiles instead of steel profiles in order to provide the necessary rigidity and increase rigidity.