Peak picking is used to determine locations of salient peaks in a graphical representation of a physical quantity. It is often used to extract possible natural frequencies from the frequency domain representation of structural responses.One of the challenges in peak picking is to establish a method to automatically distinguish peaks from data containing noise peaks. As selecting peaks intrinsically depends on human perception, algorithms for automated peak picking have exhibited only partial success to date. This paper presents an automated peak picking method that utilizes a region-based convolutional neural network with possible object locations to accurately identify the peaks. A tailored deep learning architecture is proposed, which is subsequently trained using only the peaks numerically generated by computer software. Laboratory and field tests are conducted using acceleration responses obtained from three test structures of beam, truss, and stay cable to verify the identification performance of the proposed peak detector. The proposed peak detector is shown to successfully identify most of the salient peaks with high accuracy.parameters of the physical modes are consistently found regardless of the provided system orders. 15 The modal parameters calculated from SSI or ERA with different system orders are grouped based on their similarity to each other, from which the frequently obtained are selected as the physical modes. [16][17][18][19] Neu et al. 20 and Cabboi et al. 21 further improved the approach in terms of automation by minimizing user-defined parameters. In addition, Afshar and Khodaygan 22 presented an enhanced stabilization chart for automated modal analysis. However, the identification performance is still highly dependent on the maximum system order, of which an optimal value should be provided as a priori information.Peak picking associated with frequency domain approaches has also been used to carry out automated modal analysis. [23][24][25] Peak picking on the frequency domain representation is considered as an intuitive way for operational modal analysis, as natural modes generally have salient peaks. A general approach for automated peak picking in the literature is to select maximum values of frequency domain representations of the structural responses (e.g., Fourier transform and power spectrum) from each of the user-defined subfrequency ranges, which are believed to include peaks. 26,27 This method is valid only when the subfrequency ranges are known; changes in peak frequencies due to structural damage or environmental effects can lead to the selection of undesired peaks. A user-defined threshold value was additionally introduced to filter out less important peaks in each subfrequency range. [28][29][30][31] This approach ignores peaks that are lower than the user-defined threshold and thus reduces the number of false positives; however, the imposition of thresholds for the peak amplitude and subfrequency range critically limits the practical applications of the approach to different ...