VIBRATION AND FOOTFALL ANALYSIS OF FOOTOVER Z BRIDGE

Abstract

As the population is increasing day by day, need for pedestrian bridges is also increasing day by day. With all the new technology and material quality improvement, the cross sections of the bridges are decreasing day by day. This is leading to lighter bridges with higher flexibility. In the past footbridges have always been designed for static loads only. People considered the dynamic effect of pedestrian walking as quite insignificant but after the incident of London’s Millennium Bridge, this dynamic effect has been considered significant as well. In the present study, an effort has been made to study dynamic effects on an old Footover Bridge located in Mumbai. The overall length of the bridge is about 330 m having 21.6 m span length. Two types of bridge decks are considered namely Steel deck and Steel Deck plus concrete overlay. These two types of bridge decks are modelled in ETABS along with the rest of the supporting system of the bridge. Four load cases are considered for each type of bridge, namely: Single person walking on single path, three persons
walking on a single path, three persons walking on three paths and finally crowd loading was considered over the entire span. All these Load cases are studied and compared for both types of bridge models. For the analysis, only vertical vibrations for the entire span length are considered. Horizontal vibrations are neglected because the bridge’s natural frequency is higher than 2.5 Hz. EUROCODE EN 1990 part 0, part 1 and part 3 was followed as well as limits from ISO 10137 is also considered.