The relationship between pedestrian loading and dynamic response of an FRP composite footbridge.

Abstract

Pedestrian loading on flexible structures such as footbridges, grandstands and lightweight floors is an area, which is receiving significant attention from the research community of late. One of the key parameters in determining the structural response is the frequency of the bridge. The authors are currently researching pedestrian-induced loading on flexible structures and also the use of FRP materials in construction. This paper describes the amalgamation of these two discrete research interests by detailing the material testing, design and construction of a laboratory-scale FRP composite footbridge. The bridge was constructed from glass fibre reinforced polymer (GFRP) composite beams, with GFRP lateral bracing. This structure supports a timber deck. The bridge is lightweight and the span can be altered from 6.5 m to 8.0 m clear span to adjust the structural response, by altering the natural frequency and magnitudes of displacements. The bridge can also be fixed in position through the use of removable intermediate supports. The bridge also has a force plate mounted at mid-span, facilitating direct measurement of the reaction force between the pedestrian and the structure. This paper presents the results of preliminary walking trials on this bridge in both the fixed and free suspension states, and across a range of spans, allowing analysis of the interaction between pedestrian loading and the structural response of flexible structures.