Probabilistic sensitivity studies on modal properties and response of occupied pedestrian bridge

Abstract

The enthusiastic behaviour of people on structures can cause synchronized rhythmic movements which may lead to resonance between forcing frequency and one or more natural frequencies of the structure. Such a human-structure synchronization results in strong vibrations that affect structural stability and create discomfort among people. The Indian codes and standards do not consider Crowd-Structure Interaction (CSI), resulting in an unreliable vibration assessment of structures. The present work investigates the effect of CSI on the dynamic behaviour of pedestrian bridges in the vertical direction. The system is modelled as a two degree of freedom mass spring damper system and the modal properties are determined. The modal properties and response of the system are studied for varying crowd parameters such as size and location. A probabilistic sensitivity analysis is carried out to understand the sensitivity of modal properties and response of the CSI system to the parameters of crowd and empty structure, using a variance based method. Monte Carlo simulation is used to simulate samples of the random parameters. Crowd activity frequency and generated load factor are observed to be the most sensitive parameters affecting the vibration of the structure.