Experimental analysis of the shear resistance of precast concrete T-beams with a top cast-in-place slab

Abstract

Precast concrete T-beams with a cast-in-place slab on top are structural elements that are often employed in composite construction. Despite their widespread use, some aspects of their structural behaviour upon shear forces have not yet been studied in depth. Six composite specimens with different T-shaped cross-sections and concrete qualities, and with web reinforcement, were tested to analyse the shear transfer mechanisms and to assess the contribution of the cast-in-place slab to shear strength. The shear strength mechanisms deriving from experimental observations and measurements are provided. This study indicates that: placing a concrete cast-in-place slab on top of a prefabricated T-beam increases its shear strength; interface shear strength plays an essential role in concrete composite elements’ vertical shear strength; widening the cast-in-place slab width does not increase shear strength in this test programme specimens; the compressive strength of the precast beam’s concrete significantly influences composite beams’ shear resistances. The ACI 318-19 formulation best captures the influence of concrete strength on shear strength of the three formulations considered (EC2, MC-10 (Level III) and ACI 318-19). However, all of them tend to underestimate shear strengths compared to the experimental results.