It is now well established that concrete deck slabs of slab-on-girder bridges subjected to concentrated loads develop an internal arching system provided that certain conditions of confinement of the concrete are met. Because of this arching system, the deck slab, being predominantly in compression, fails in punching shear rather than in flexure. This aspect of deck slab behaviour, coupled with the corrosion problems associated with steel reinforcement in concrete, has prompted the authors to investigate the feasibility of fibre-reinforced concrete decks that are entirely devoid of steel. Through tests on a small number of half-scale models, it has been established that fibre-reinforced concrete slab with inexpensive non-ferrous fibres is indeed feasible, provided that the top flanges of the steel girders are connected just below the deck by transverse steel straps and the concrete deck is joined to the girders and diaphragms by shear connectors. The straps and shear connectors together provide the restraint necessary for development of the internal arching system in the slab, whilst the fibres control cracking due to the effects of shrinkage and temperature in the concrete. This paper describes the exploratory model tests and presents their results. Key words: deck slab, fibre-reinforced concrete, internal arching, punching shear, slab-on-girder bridge.

The grillage analogy method for analyzing bridge superstructures has been in use for quite some time. The idealization of a bridge by a grillage is not axiomatic and is not without pitfalls. An attempt is made in this paper to provide guidance on grillage idealization of various types of structure, together with the relevant background information. Specifically, the paper deals with the idealization of slab, beam-and-slab, cellular, and voided-slab bridges. Idealization of slabs of linearly varying thickness is also discussed. Guidance is provided on the mesh layout. Keywords: analysis, beam-and-slab bridges, cellular structures, flexural rigidity, grillage, idealization, load, mesh, slab bridges, torsional rigidity, voided slab.

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