Effect of Concrete Compressive Strength on Shear Strength of Self Compacted R.C Rectangular, T and I Sections Beams

Abstract

Eighteen self-compacted concrete (SCC) beams at different shaped were designed and tested  to determine the effect of using SCC on the shear strength under two concentrated loads. The tested beams were divided into three groups according to the shape of the cross section, rectangular sections, T-sections and I-sections. Each group was divided into two series  with and without stirrups. All the series beams have the same longitudinal steel ratio, gross section area and clear span to effective depth ratio but have different values of compressive strength ( . It was found that the ultimate shear strength predicated by ACI 318M-08 is conservative relative to  the experimental values, the ultimate shear strength of SCC beams with and without stirrups increased when the compressive strength of the SCC increased. When the compressive strength increased  from (29.36 to 49.2 MPa) at clear span to effective depth ratio (ln/d) equal to 5.84 the ultimate shear strength of SSC beams  without stirrups increase about 31.22%,55.55%and 18.931% for rectangular, T- section and I-section respectively ,while the ultimate shear strength of SCC beams with stirrups increased 17.17%,28.57%and 15.584% for rectangular, T- section, I-section respectively .The ultimate shear strength of SCC  rectangular beams with stirrups  increased about 85.41%, 68.96% and 65.52% as compared with ultimate shear strength without stirrups at compressive strength 29.36,41.42 and 49.2 MPa respectively, the ultimate shear strength of SCC T-beams with stirrups  increased about 133.3%, 97.916% and 92.857% as compared with ultimate shear strength without stirrups at compressive  strength  values of 29.36,41.42 and 49.2 MPa, respectively . Finally the ultimate shear strength of SCC I-beams with stirrups increased about 44.6%, 38.1% and 40.53% as compared with ultimate shear strength without stirrups at compressive strength values of 29.36,41.42 and 49.2 MPa respectively.