Profiled metal plate – Cork mat loading systems on cellular FRP bridge decks to reproduce tyre-to-deck contact pressure distributions

Abstract

Flat steel plates on rubber pads are commonly used for patch loading of cellular GFRP bridge decks. However, the resulting pad-to-deck contact pressure distributions (CPDs) differ from tyre-to-deck CPDs, so such plates cannot underpin reliable evaluation of deck fatigue performance local to tyre loads. Steel plates with curved soffits can significantly improve the approximation to the tyre effect, the extent of the improvement depending on the form of the curved surface. To that end, this paper reports four novel advances. First, for a reference CPD characteristic of tyre-to-deck interaction, this curved surface is defined as the FE-predicted deflected profile of the deck’s flange under that CPD. Second, tests show that relative to a flat soffit, this curved soffit on a cork mat enables far better approximation to the reference CPD. A special film used to quantify the CPDs does so via a one-way process which is a function of contact pressure, so use of the film’s results to infer pressure redistribution requires care. Third, the effects on the CPD of changes to the loading surface (useful in the context of different tyre inflation pressures, for example) are demonstrated. Fourth, the curved soffit CPDs are shown to exhibit significant sensitivity to the presence of cracks in the deck, thus rendering the profiled plate – mat system eminently suited to damage detection in decks. Finally, extension of this work (including predictive modelling equipped with material and geometric nonlinearities) to decks with bonded anti-skid surfacings is discussed.