Synopsis
With a growing predilection for landmark bridge structures, particularly lightweight pedestrian crossings in town centres, comes a greater need to consider, in detail, the dynamic effects due to pedestrian loading. As structures become more slender relative to the structure mass (ratio of stiff ness to mass reduces) and pedestrian loading becomes a more significant proportion of the total load, natural frequencies reduce and the acceleration response of the structure to pedestrian loading increases to the point where it can become disconcerting for the unsuspecting user. Once the natural frequency for such structures reduces to levels corresponding to normal walking frequencies, the bridge becomes susceptible to resonance and magnified acceleration responses. This may require modifications to the bridge to achieve an acceptable or imperceptible acceleration response to normal pedestrian usage. This paper reviews the design process that was undertaken to resolve the problem of the 'lively' response of a pedestrian footbridge at the Eagles Meadow development in Wrexham.