Analytical Models for Shear-bearing Capacity of Hollow Core Beams Strengthened with HPC and Shear Steel Rebars

Facing the insufficient shear-bearing capacity of Hollow Core Beam (HCB), the High-performance Concrete (HPC) and shear steel rebars were proposed by the authors. However, investigations of the maximum diagonal crack width of the strengthened HCB specimens were scarce. Simultaneously, there were no details for the shear failure mechanism of the complex interface between HCB and HPC. For this reason, the failure modes and stirrup stress were first investigated. A simple model of maximum diagonal crack width of the strengthened HCB specimens was suggested. The maximum deviation of predictive value and test result was within 3%. Secondly, a modified truss-arch model of strengthened HCB specimen was proposed, considering the tensile behavior of the HPC. The average ratio of estimated and experimental results was 1.02. Finally, the shear-bearing capacity of strengthened HCB specimens was suggested considering the shear contribution of the HPC, shear steel rebars and interface bonding force. Compared with the previous shear test results reported by the authors, the maximum deviation was within 1%. To validate the accuracy of the formula, the other HCB specimen was used to evaluate the maximum deviation within 5%. It can be concluded that the proposed formula agrees well with the test results.