Foundation scour and its effect on the performance of FlexiArch™ modern arch bridge system

FlexiArch^TM is a novel arch bridge system comprising of precast concrete voussoirs that require no centring during the placement stage at the bridge site, overcoming a time consuming and costly constraint in the traditional method of arch bridge construction. The behaviour of the novel FlexiArch system under foundation scour has not been investigated previously. Moreover, earlier work on bridge scour separated the scour phenomena from the structural behaviour of the bridge in their experiments and/or analysis, where in reality the two phenomena interact. This paper presents flume experiments planned to study the fluid/structure interactions at a 1:10 model FlexiArch^TM bridge under pressurised flow conditions. The preparations for the experiments are underway. Laser and digital image analysis techniques have been developed to characterise the flow through the arch as well as the scour under different flow conditions and to monitor the structural displacements as the scour progresses. This will enable scour predictions of the excess scour due to the presence of the pressurised flow conditions to be made and to better understand foundation layout and allow engineers to identify suitable countermeasures to scour. Identifying the changes in load-response behaviour of the model as critical levels of scour occur will provide fundamental understanding of FlexiArch^TM behaviour necessary for the health monitoring of such bridges in the field.