Experimental frequencies and damping ratios for historical masonry arch bridges: Fid-Bau Portal

Experimental frequencies and damping ratios for historical masonry arch bridges

Bayraktar, Alemdar / Türker, Temel / Altunişik, Ahmet Can

Highlights • The experimental frequency, mode shapes and damping ratios of historical masonry arch bridges are presented. • Eight historical masonry arch bridges with different spans are investigated. • Different test setups using sensitive seismic accelerometers are given for the historical masonry arch bridges. • The dynamic characteristics are identified by EFDD and SSI techniques. • An equation between natural frequency and main arch span are proposed.

Abstract Historical masonry arch bridges composed of foundation, arch, walls, slab and infill are very complex structures. The dynamic characteristics of the masonry arch bridges using analytical or numerical methods cannot be determined accurately. The aim of this study is to determine the frequency and damping ratios of historical masonry arch bridges experimentally. Eight historical masonry stone arch bridges with different spans constructed at various times are selected for the application. The selected bridges were built with stone and horosan mortar. The experimental dynamic characteristics of the bridges are determined using the Operational Modal Analysis Method. Sensitive seismic accelerometers with cables are used in ambient vibration tests. The frequency, damping ratio and mode shapes of the selected bridges are obtained using the Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) Techniques. The experimental frequencies, damping ratios, and mode shapes of the bridges are compared with each other. In the end of the study, a formula for the first frequency, a value of damping ratio and the types of mode shapes are recommended for the historical masonry stone arch bridges.