Shear Strength of Fixed Composite Beams Combining Precast Concrete and Cast-In-Place Concrete

The use of composite members using precast concrete (PC) and cast-in-place (CIP) concrete with different compressive strengths has increased. However, current design codes do not clearly define the shear strengths of composite members with different concrete strengths. In this study, the shear strength of PC-CIP composite beams with dual concrete strength (24 MPa and 60 MPa) was experimentally evaluated. The test variables included the area ratio of two different concretes, the use of stirrups and support conditions. The test results showed that flexural cracks and splitting cracks along longitudinal top rebars affected the strength of composite beams. Although the current design code predicts the shear strength of fixed composite beams on the safe side, the shear strength predictions of composite beams without stirrups were largely conservative.