Flexural behavior of prefabricated composite beam with cast-in-situ UHPC: Experimental and numerical studies

Steel-concrete composite beams, which consist of steel beams, reinforced concrete slabs, as well as headed shear studs, are getting widely used in engineering structures. This paper proposed an innovative prefabricated composite beam consisting of two full-depth precast concrete (FDPC) slabs with extending rebars and reversed grooves, an H-shaped steel beam with welded shear studs, the additional transverse rebars and the cast-in-situ ultra-high performance concrete (UHPC). Compared with conventional steel-concrete composite beams, the innovative prefabricated composite beam retains the advantages of rapid assembly and construction, while maintaining favorable flexural performance and reducing the excessive costs and potential construction chal-lenges due to application of the FDPC slabs and cast-in-situ UHPC. Experimental study was carried out to investigate the flexural behavior of prefabricated composite beam. Failure modes, flexural capacity, deformation characteristics, and crack propagation were observed. Refined finite element (FE) models were established, calibrated against test results and then adopted to simulate the load-carrying capacity of the proposed pre-fabricated composite beam. The effects of critical design parameters such as cast-in-situ concrete strength, steel beam strength and section height, shear stud diameter and interval on the flexural behavior of prefabricated composite beam were investigated. The analysis results indicated that the proposed prefabricated composite beam exhibited excellent and expected flexural behavior, and the failure mode was concrete crushing and steel beam yielding. The prefabricated composite beam is regarded as partially connected composite beam. Through geometrical parameters correlation analysis, the prediction formulas of flexural capacity and bending stiffness of the partially connected composite beam were deduced and validated, which provided a fundamental basis for further study and application.