Experimental study of concrete decks restrained by steel strap

Abstract

The steel-strapped deck slab is a new type of bridge slab, eliminating the conventional reinforcing bars in concrete while increasing arching action by effectively restraining laterally the straps among the deck slab, girders and straps. In this study, a fibre-reinforced polymer bar is placed on the upper and lower parts of decks to improve the flexibility and to control cracking. The test results showed that steel-strapped deck slabs, even with a fibre-reinforced polymer bar of only 0·15% compared with 0% fibre-reinforced polymer bar, showed significantly improved load-carrying capacity and flexibility. A fatigue test was performed as well on steel-strapped deck slabs. As a result, the serviceability was found to be within allowable limits in terms of crack control and residual displacement after 2 000 000 cyclic loadings. However, the shear failure strength of the decks is shown to be commonly underestimated. A punching shear strength equation was developed, accounting for a real failure shape and the lateral restraint effect of the straps. This equation can be used to estimate the strength accurately within approximately 4% of the deviation compared to test results.