Authors: A. Dick, M. T. Braz-César

Masonry arch bridges are generally old structures with historical and patrimonial value, with were built based on empirical rules for traffic loads significantly different of those existents nowadays. Considering the concern of modern engineering in avoid the resonance phenomenon, the study ofthe dynamic properties of these structures is fundamental, as it will allow to know their behavior under the dynamic loads imposed on the structure. The present study is based on the determination of dynamic parameters, namely own frequencies associated with vertical vibration modes for a set of thirty-three masonry arch bridges located in Bragança district, Portugal. These parameters were obtained through in-situ environmental vibration tests and the identification of the frequencies themselves was performed in the frequency domain using the peak-piking technique. The identification of the own frequencies allowed to compare the influence of some geometric parameters of the bridges and their relation and approximation with the frequency range of the excitation source, thus 36.36% of the bridges present frequencies in the natural frequency range of the vehicles.

A. Dick ¹ | M. T. Braz-César ²
1 Mestre em Engenharia da Construção, ESTiG – Instituto Politécnico de Bragança
2 Professor Adjunto, ESTiG – Instituto Politécnico de Bragança