Enhancing the Structural Performance of Masonry Arch Bridges with Ballast Mats

Abstract

A large portion of the railway bridge stock in many countries is comprised of masonry arch bridges. During recent years, more attention has been paid to the maintenance of such structures. Rehabilitation and retrofitting methods have been proposed to enhance the performance of masonry arch bridges and extend their service life. Because a large portion of forces exerted on such structures comes from the railway track and passing trains, structural elements are added to the track to reduce the forces transmitted to bridges. One such element is the ballast mat, which, according to suppliers, has a positive impact on the structural performance of the track. This paper tries to assess the effects of ballast mats on the structural performance of masonry arch bridges through dynamic load tests. To do so, a 70-year-old masonry arch bridge was instrumented with deflection meters and accelerometers and dynamic load tests were carried out before and after installing ballast mats. According to test results, vertical deflections at different points on the bridge remained the same, with a deviation of less than 2%. On the other hand, vibrations on the structure were reduced significantly. Vibrations at different locations in the structure were reduced in the range of 65–85%.