Membrane action in plain concrete slabs under concentrated loading.

In certain circumstances, the elimination of steel bar reinforcement from c oncrete slab construction is made possible by the presence of compressive m embrane action. Design practice cannot conveniently take advantage of this, because rigorous strength calculations are not straightforward. A direct m ethod of calculating, by hand, a suitable load capacity has been developed which provides a load improvement factor to be applied to the pure flexure ultimate load. Such a method is unsatisfactory for plain (i.e. unreinforced ) concrete slabs. This paper shows how the method can be employed for calcu lations on plain concrete bridge deck slabs and compares the results with l aboratory experiments.