S.-W. Shin’s scientific contributions

Fifty-three reinforced concrete deep beams with compressie strengths in the range of 23 MPa ≤ f c′ ≤ 74 MPa (3335 psi ≤ f c′ ≤ 10,730 psi) were tested to determine their diagonal cracking and ultimate shear capacities symmetrically under two-point loading. The effective span-depth ratio l e/d was varied from 3.0 to 5.0, and the shear span-effective depth ratio a/d from 0.5 to 2.0. All the beams were singly reinforced with ratio pt of 0.0129, 0.0156 and ratio of ρ v from 0 to 0.0034, and ρ h from 0 to 0.0094, respectively. The ultimate shear failure mode of deep beams was governed by a/d regardless of concrete strength. At a lower a/d, deep beams with high-strength concrete failed abruptly without any caution, which could be seen in deep beams with normal-strength concrete. Test results indicate that the ultimate shear strength of deep beams was determined predominantly by a/d. For all tested beams, ACI Code Eq. (11-29) and (11-30) are conservative and underestimate the effect of concrete compressive strength f c′ and that of longitudinal steel reinforcement ρ t in deep beams using high-strength concrete. Addition of horizontal shear reinforcement does not improve the ultimate shear strength with decreasing a/d in deep beams with high-strength concrete.