NONDESTRUCTIVE EVALUATION OF THE DYNAMIC-RESPONSE OF A BRICKWORK ARCH

This paper presents results from an ongoing investigation into non-des tructive test methods which could be successfully used in conjunction with current inspection and assessment techniques, It aims to assist l ocal authority engineers facing reassessment of their bridge stocks fo r up to 44 t gross vehicle, and 11 . 5 t axle weight limits, The use o f impact hammer testing to study the dynamic response of a semicircula r brickwork arch ring of 2 m span is described, The arch's response wa s analysed in both the time and frequency domains, Dynamic finite-elem ent analyses were used to model its behaviour under impulse loading, T he results, both in the time and frequency domains, compared well with those obtained experimentally, The resonant frequencies, and their co rresponding vibration mode shapes, were successfully separated, The ef fects of spandrel walls and a granular backfill over the extrados were analysed, A simple defect was introduced in the form of a void in the fill over the crown; its detection was possible from observed changes in the frequency response function (FRF), The principal conclusions w ere that the method could be further explored within the context of st ructural integrity assessment of arch bridges.