Elastic Behaviour of Open Sandwich Bridge Decks

The requirements for lateral buckling restraint of I-section beams or purlins by profiled sheeting attached to the top flange are reviewed. Theoretical and simplified methods are presented to determine the effective slenderness of a series of beams as a function of the rigidity of the sheeting acting as a shear diaphragm. These methods have been confirmed by a number of tests on 7 m span beams. Effective lateral restraint requires that the sheeting possesses sufficient strength and stiffness. This is influenced by the spacing of the fasteners at the ends of the sheets and along the sheet seams. For most practical sheeting and beam arrangements, the lateral support produced will be such that the beams may be designed to their full in-plane strength. A method for estimating the shear forces developed in the sheeting is provided, and shear forces may generally be shown to be smaller than those given by Code requirements. R.M. Lawson and D.A. Nethercot

An analytical model based on the space truss concept is proposed for predicting the torsional strength of steel-fibre-reinforced concrete beams. The method is validated by comparison with the test data available in published literature for the following cases: -beams provided only with fibre-reinforcement -prestressed fibre-concrete beams -fibre-concrete beams provided with longitudinal steel only -fibre-concrete beams provided with longitudinal steel as well as stirrups R. Narayanan and A.S. Kareem-Palanjian