Experiment Study on Residual Flexural Capacity of Prestressed Concrete Deck Slab Under Fatigue Loading

Abstract

The deterioration of a concrete deck damaged by repeated traffic loads could directly affect its performance. Two full-scale specimens modified from a precast, prestressed concrete (PC) deck slab on a 12.65-m-wide composite bridge with twin I-girders spaced at 7.05 m were tested to study the degradation of mechanical performance of the slabs under fatigue loading. The depth of the slabs was 30 cm at the midspan and 40 cm at the two supports. One specimen was 3.0 m wide and conducted a three-stage fatigue loading before the static destructive loading, the other was 1.5 m wide and performed a static load test to failure only. The ultimate strength of specimens was obtained, and the variation of deflection, reinforcing strain, and cracks were discussed. The test results showed that the failure mode of the PC slabs was flexure subjected to static load. Fatigue loading significantly degenerated the stiffness of the slab, and the maximum stiffness reduction was about 35.2 %. The distribution scale of cracks was expanded about twice as much at the same load level under the fatigue loading. It could be deduced that the fatigue loading could enlarge the crack width, by comparing the measured results of concrete crack widths of the two specimens, however, the design provisions did not take this into account. A comparison between the transformed flexural capacity of the two specimens showed the residual flexural capacity was reduced by 7.8 %. Moreover, an analysis model was developed to predict the residual flexural capacity of PC slabs.