Performance of Inertial Mass Controllers for Ultra-Lightweight Footbridges: A Case Study

Abstract

The increasing use of lightweight materials in construction, such as fiber reinforced polymer (FRP) composites or aluminum, together with rising architectural tendencies towards slender and stunning layouts are enabling to dramatically decrease the weight of contemporary structures. This fact involves a positive reduction of the structural carbon footprint, but it poses a challenge to complying with vibration serviceability limit state (VSLS) under human-induced loading. Indeed, ultra-lightweight structures (with relatively low inherent mass and damping) may undergo vertical vibration in a broader frequency band than those built in the past and be prone to human-structure interaction (HSI), which should be considered when assessing VSLS of these structures. Instead of adding structural mass or performing expensive structural stiffening to rectify the vibration problem, the integration of smart damping strategies could be an optimum solution that has additional benefits of preserving lightweight nature of these structures. This paper presents a case study of vibration control of an ultra-lightweight FRP truss footbridge. This work investigates the influence of three types of inertial mass controllers (passive, semi-active and active) on the vibration control of the bridge in the presence, as well as in the absence, of HSI. It was found that active vibration control was the less deteriorated when considering HSI in comparison with passive and semi-active control strategies.