Abstract:
The following is an overview of a field testing program carried out to investigate the dynamic properties of in-service bridges. Two bridges in the Auckland region, Caitcheon’s Bridge and Glasgow’s Bridge, were subjected to forced vibration testing and a system identification process. The aim of this testing was to determine the in situ dynamic response of each bridge system accounting for both the structural and foundation components. Each bridge was excited in both the transverse and longitudinal direction using an eccentric mass shaker and the response measured with a dense sensor array of up to 160 channels. Testing was performed over two nights at each bridge, with the extensive sensor array and eccentric mass shaker installed and removed each night in order to minimise the impact on normal bridge operations. A description of the test bridges and review of the testing procedures used are first summarised. The characteristics of the overall response of each bridge are then presented with a particular focus on the relative stiffness contributions from the abutments and pier foundations.