Vibration characterisation of aluminium pedestrian bridges

Abstract

Despite several full-scale applications in Canada, the vibrational characteristics and performance of aluminium pedestrian bridges have not been studied comprehensively in the literature. There is a large degree of variability between design codes and standards, particularly in North America and Europe. This is in part due to a lack of comprehensive experimental test data on full-scale pedestrian bridges. This is compounded by a lack of agreement between researchers on the characterization of pedestrian induced loads and the interaction between loads and the structure. This thesis aims to bridge this gap by building and testing full-scale aluminum pedestrian bridges in a controlled laboratory test program. Results from the experimental program are presented, discussed in detail, and used to estimate the vibration characteristics of an aluminium pedestrian bridge of various lengths. These characteristics include the modal properties -- natural frequency, damping ratio, and mode shapes -- and human-structure interactions measured using accelerometers, load cells, and strain gauges. Using multiple signal processing techniques, these characteristics were extracted from the data. The results from the pedestrian loading tests were then used to assess the bridge specimens through the above-mentioned design codes. Finite element models of each specimen were built and used for parameter studies and model verification.

These data from full-scale pedestrian bridges are likely to shed new light on their vibrational behaviour and performance, and allow aluminium bridge designers to create competitive alternatives to bridges constructed with conventional materials. It is also anticipated that these tests will form a foundation for future research in the area of pedestrian bridge load modelling.