Flexural Behavior of Steel-Precast Concrete Composite Girder Using UHPC Shear Pockets

This paper presents an experimental investigation into the behavior of a composite concrete steel bridge girder under four point loads. Five RC specimens have been considered in the experimental tests with a UHPC haunch layer and variable number of shear pockets. One specimen has been represented by the specimens to be the reference specimen, while the other specimens tested as strengthened composite beams. Two variables have been considered in the experimental tests: the number of shear pockets and the alignment line of bolt studs (straight and zigzag lines). The deflection at the center of the beam, the first crack, the cracking load, and the crack pattern were studied. The test results show that it was determined that the ultimate load capacity of zigzag-line alignments for three shear pockets increased from the reference beams with 63.91%. Whereas, in comparison to reference specimens, ultimate load capacity for all beams increases by about 47% for 60%. In addition, no splitting cracks are observed in UHPC shear pockets, and no concrete crushing occurs on the surface of the UHPC slab at the failure of beam specimens. The UHPC and steel exhibit good composite action, and the flexural performance of steel-UHPC composite beams is significantly improved.