Evaluation of the Equivalent Moving Force Model for Lightweight Aluminum Footbridges in Simulating the Bridge Response under a Single-Pedestrian Walking Load

Abstract

Due to its high strength-to-weight ratio, corrosion resistance, extrudability, and recyclability, there is a growing demand for the use of aluminum for sustainable bridge constructions, especially for footbridges. Owing to their light weight and lively characteristics, vibration serviceability often governs the design of aluminum footbridges. To better design these bridges, it is necessary to accurately predict pedestrian-induced walking loads. To this end, the existing design codes around the world have adopted the periodic moving force model (MF) due to its simplicity. However, the appropriateness of the MF model is being questioned, mainly in capturing the effect of the human–structure interaction (HSI), which can be pertinent to the design behavior of aluminum footbridges. A biomechanical-based spring-mass-damper (SMD) model was developed in the literature to simulate the HSI phenomena, which has never been validated for aluminum footbridges. Moreover, to simplify the complexity associated with SMD models, the experimental moving force model (EMF) was developed that can capture the effect of the HSI in an equivalent sense. This study aims to evaluate the capability of the SMD and EMF models to capture the real behavior of aluminum footbridges. To do so, the vibration responses of two aluminum footbridges are simulated numerically as a single-degree-of-freedom (SDOF) system under single-pedestrian walking loads employing the SMD, EMF, and MF models, which are then compared and validated based on already-available experimental observations. Finally, recommendations are made for the most suitable model for the vibration prediction of aluminum footbridges.

Keywords

• aluminum footbridges
• human–structure interaction
• biomechanical models
• conventional models
• moving force model
• experimental moving force model