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UBC Theses and Dissertations

Operational modal analysis, model updating, and seismic analysis of a cable-stayed bridge McDonald, Steven


The Port Mann Bridge is currently one of the longest cable-stayed bridges in North America and the second widest bridge in the world. It is a cable-stayed bridge consisting of 288 cables, two approach spans made of concrete box girders and precast deck panels, and a main span consisting of steel girders and cross beams with precast deck panels. This work sets out to accomplish three main goals: study the dynamic behaviour of the Port Mann Bridge, calibrate the finite element model, and study the effects of model updating using a seismic analysis. The dynamic behaviour of the Port Mann Bridge’s main span is studied using experimental data from field ambient vibration tests and from a structural health monitoring network. A finite element model is created by importing a version of the structural designer’s model and editing it based on design drawings. In order to assess what parameters would be feasible to calibrate, a sensitivity analysis is carried out using various material properties and boundary conditions. The model is then updated to match the experimental analysis results by varying multiple parameters. Finally, the calibrated model is compared to the original model by completing a linear time history analysis. A suite of ground motions were selected and scaled to match specific points on the response spectrum corresponding to the first few periods of the structure. Multiple critical locations are monitored in the time history analysis, and data from these locations are compared before and after calibration to examine the effect of model updating. The study concludes that model updating has a large effect on the predicted seismic behaviour of the bridge, which proves the importance of calibrating finite element models and maintaining physically meaningful parameters. It also shows that having a structural health monitoring program is very important for current and future research endeavours.

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