Study on Behavior of Waffle-Type Uhpc–Gfrp Composite Slab Under Two-Point Load

Traditional concrete bridge deck is usually the first component to appear the disease in the bridge structure, since the concrete in tension zone of traditional concrete bridge decks is liable to crack under vehicle loading. This study proposes a novel waffle-type UHPC–GFRP composite slab that can solve the cracking problem of traditional concrete bridge decks. The GFRP grid was partially embedded in the UHPC to transfer the shear force between the grid and UHPC. The remainder of the GFRP grid was exposed to form a ribbed structure similar to a "waffle plate." Five composite slab tests were conducted to investigate the mechanical properties of the proposed composite slab. Accordingly, the influences of the shear span-to-depth ratio, thickness of the UHPC layer, and embedded depth of the GFRP grid on the bending behavior of the composite slab were considered. The experimental results revealed three failure modes of the composite slabs: bending failure, shear failure, and GFRP interlaminar shear failure. The change in the shear span-to-depth ratio directly affected the failure mode of the composite slab. More specifically, the deeper the embedded depth of the GFRP grid, the higher the ultimate strength of the composite slabs. Lastly, a calculation method for the new waffle-type UHPC-GFRP composite slab is proposed, and the calculation error is controlled to be within 12%.