Train Buffeting Measurements on a Fibre-Reinforced Plastic Composite Footbridge

Abstract

This paper presents a case study of the Bradkirk Bridge, which is a foot bridge built over a railway line. The bridge, consisting of two 12 m spans plus staircases, was constructed using glass/epoxy fibre-reinforced plastic (FRP) material and it is believed to be one of the first moulded FRP bridges to be established over a mainline network.Due to the lightweight nature of FRP materials, train buffeting of footbridges is an area of considerable interest for designers of FRP structures. The authors have carried out a study comparing onsite-measured vibration data using finite element analysis (FEA) and analytical methods to investigate the effect of buffeting on the Bradkirk Bridge. The aim of the study was also to understand, in general, the dynamic response of the structure and to obtain the natural frequencies.It was found that at the low speed of trains measured (112 km/h), there was no adverse effect on the structure and the structure was found to have a high fundamental natural frequency. There was also a good correlation between the data measured on the bridge and the FEA and theoretical predictions of natural frequencies.