Strengthening fatigue-cracked steel bridge decks

Abstract

In slender orthotropic decks of steel bridges, the dynamic interaction between vehicle tyres on flexible asphaltic pavement and the deck structure plays an important role on stress amplitudes. This involved interaction mechanism is brought into the discussion on the main causes of the pavement disruption and of the observed cracks in a large steel bridge, which has been frequently damaged by fatigue cracks in welded joints and geometric details under random stresses produced by traffic loading. Numerical modelling and experimental strain measurements performed both in situ and in the laboratory on a prototype scale model of the actual steel deck. Proposed solutions include adding a reinforced concrete pavement, either as a sandwich structure with a visco-elastic layer in between the steel plate and the concrete slab, or as a composite deck formed by fixing the concrete slab to the steel plate with stud connectors. It is shown that visco-damping and composite stiffness properties led to substantial reduction of both longitudinal and transverse bending stresses, enhancing the fatigue performance of these bridge decks.