This study aims to investigate the dynamic behavior of a one-span historical masonry arch bridge. For this reason, the masonry bridge with 15.5m in length and 4.75m in width was chosen and the modal parameters were obtained by performing numerical analyses and experimental measurements. Operational Modal Analysis technique is utilized for experimental study to determine modal parameters of the historical masonry bridge. Sensitive three-axial accelerometers were located on critical points on the bridge span and signals originated by accelerometers were collected to quantify the vibratory response of the historical bridge. The Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification method are employed to identify the natural frequencies, mode shapes, and damping ratios experimentally. The 3D finite element modeling of the historical masonry bridge was created and the natural frequencies and mode shapes of the bridge were determined numerically. Experimental results were compared with those of the finite element analysis of the bridge. It can be noticed significant differences when comparing the results of the experimental and numerical with the initial conditions. Therefore, the finite element model is calibrated by using the response surface method according to the experimental results to minimize the uncertain finite element modeling parameters of the historical masonry arc bridge such as material properties and boundary conditions. At the end of the calibration process, the maximum differences between natural frequencies obtained experimental measurements and numerical analysis decreases from 4%-50% to 0.5%-2.5%. The final calibrated finite element model for the masonry bridge is able to produce natural frequencies in close agreement with the measured ones.

This study aimed to parametrically investigate the changes in modal frequency values on a steel beam caused by specified damaged schemes. In this context, the ANSYS Workbench software program was used to create a steel profile's finite-element model. A cantilever steel beam profile is created with a 60x60 mm cross-section and 3m length utilizing single-sided fixed support. In the finite-element model, the crack depth, width, and distance to the support were parametrically assigned as the damaged scheme to the steel profile. To investigate the effects of those damages on the modal frequency values of the steel profile, first of all, the modal frequency values for undamaged cases corresponding to the first ten-mode shapes were obtained. Then, the specified crack properties were determined parametrically, and the changes in frequency values for damaged cases were examined. In addition, a comparative evaluation of the effect of crack properties on the natural frequency of the steel element was performed by utilizing response surface and six sigma analysis. The analysis results demonstrated that specified crack schemes have different effects on different modal natural frequencies. The applied response surface and six sigma analysis provided important statistical data on the modal natural frequency values of the steel beam.