Bridges

Half joints were introduced into bridges to simplify design, construction and allow for bridge movements. The sudden collapse of a concrete half joint overpass bridge in Montreal, Canada, after about forty years in service, prompted concern within the bridge community regarding the inherent risks involved in this type of bridges. This paper gives an outline of Road and Traffic Authority’s (RTA) different type of half joint bridge stocks and examines in detail the challenges faced by RTA in maintaining these bridge stocks for ever increasing road traffic. It also discusses the maintenance strategy currently under development at RTA to sustain these bridges for future generation. Recently a detailed analytical study was carried out at RTA for a half joint concrete bridge in Cooma, New South Wales. This paper highlights how Finite Element based techniques can be utilised to arrive realistic wheel load transfer into individual half joints and compares these results against the traditional code based Distribution Factor methods. It also addresses how concrete stress field based strut and tie modelling can be used to assess the resistance capacities of these half joints at the Ultimate Limit State.