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The shear tests are conducted on six precast segmental concrete beams (PSCBs) in this paper. A new specimen design scheme is presented to compare the effects of segmental joints on the shear performance of PSCBs. The failure modes, shear strength, structural deflection, stirrup strain, and tendon stress are recorded. The factors of shear span ratio, the position of segmental joints, and hybrid tendon ratio are focused on, and their effects on the shear behaviors are compared. Based on the measured responses, the shear contribution proportions of concrete segments, prestressed tendons, and stirrups are decomposed and quantified. With the observed failure modes, the truss–arch model is employed to clarify the shear mechanism of PSCBs, and simplified equations are further developed for predicting the shear strength. Using the collected test results of 30 specimens, the validity of the proposed equations is verified with a mean ratio of calculated-to-test values of 0.96 and a standard deviation of 0.11. Furthermore, the influence mechanism of shear span ratio, segmental joints, prestressing force, and hybrid tendon ratio on the shear strength is clarified. The increasing shear span ratio decreases the inclined angle of the arch ribs, thereby reducing the shear resistance contribution of the arch action. The open joints reduce the number of stirrups passing through the diagonal cracks, lowering the shear contribution of the truss action. The prestressing force can reduce the inclination of diagonal cracks, improving the contribution of truss action. The external unbonded tendon will decrease the height of the arch rib due to the second-order effects, causing lower shear strength than PSCBs with internal tendons.
Yan et al. (Mon,) studied this question.