Evaluation of seismic response of historical masonry arch bridges for different damping ratios

Historical bridges are important structures of our cultural heritage. There are many historical masonry bridges built in different periods in the World, bearing traces from culture and civilization in which they were built. Some of these bridges lost their strength and destroyed over time due to the effect of human factor and natural events (earthquakes, floods, winds, etc.). The bridges over the earthquake region are constantly exposed to seismic effects. Therefore, earthquake responses of the historical masonry arch bridges that have survived to present-day need to evaluate correctly to restore and protect them properly. In this thesis, earthquake acceleration record which has different damping ratio is investigated on behavior of historical masonry bridges. It is also aimed to obtain more reliable results for the earthquake responses of historical bridges. For numerical analysis, historical masonry Tağar Bridge which located in Çemişgezek town of Tunceli is selected. Three dimensional finite element model of the bridge is generated with finite element method. Dynamic properties of the bridge are obtained by the modal analysis which performed in SAP2000 finite element software. Time-history analyses are performed for %2, %5, %7 and %10 damping ratios. In these analyses, acceleration records of 1992 Tunceli earthquake is used as a seismic effect. As a result of the analyses, the effect of different damping ratios on seismic responses of historical masonry bridges is investigated by using time-history graphs of displacement and stress observed on the bridge. According to the analyses, the maximum displacements and stresses occurring in the historical bridge are obtained for Rayleigh, mass proportional and stiffness proportional damping type, respectively. For all damping types, it is observed that the displacement and stress values acquired in the bridge decrease while the damping ratio increases. Maximum and minimum displacement values are obtained at the stiffness proportional damping type and the Rayleigh damping type, respectively. The stress values occurring on the bridge are close to each other for all three damping types. However, the minimum stress values are obtained in Rayleigh type damping and the maximum stress values are obtained in stiffness proportional damping type.