Modal analysis for masonry arch bridge spandrell wall separation identification

The arch bridge forms an important part of our infrastructure, and maintenance of the bridge stock is becoming increasingly expensive. This paper presents the results of a nondestructive investigation of large scale model brickwork arches. Experiments were undertaken on brickwork arches using modal testing. The key features detected were: the effect of load on the backfill's surface, and the effect of spandrel wall separation from the arch itself. Mode shapes, fundamental frequencies, and damping ratios are presented for both qualitative and quantitative analysis of arch behaviour. Changes in these parameters were used to detect defects in the structures; as such the method may prove useful as a tool to assist civil engineers currently undertaking major bridge inspections.