Shear Behavior of Composite Beams With Open‐Web π‐Shaped Steel Partially Encased by Concrete

ABSTRACT Partially encased composite (PEC) structure, easily prefabricated and assembled, is widely used in prefabricated construction. To improve the web utilization and the productivity of the PEC structure, a new PEC beam with open‐web π‐shaped steel is proposed in this paper. Notably, the distinctive feature of this beam is that concrete can be one‐time poured. Four open‐web PEC beams with varying shear span ratios (1, 2, and 3) and web void rates (67.7% and 51.6%) were tested under shear loads. During experimental tests, the shear span ratio primarily influenced the failure mode, whereas the web void rate affected the later working performance of the beam. When the shear span ratios were 1, 2, and 3, the diagonal compression failure, constrained shear‐compression failure, and diagonal‐tension bonding failure occurred, respectively. The web void rate almost did not affect the failure mode of this open‐web PEC beam. The experimental results revealed a significant improvement in the deformation capacity of these PEC beams with an increased shear span ratio, but the initial shear stiffness and capacity diminished. When the shear span ratio increased from 1 to 3, the shear capacity of the PEC beam decreased by 35.62%. Furthermore, as the web void ratio decreased from 67.7% to 51.6%, the deformation capacity of the PEC beam improved, and the shear capacity increased by 13.0%. At last, a shear capacity formula for the open‐web PEC beam was proposed based on the superposition principle. The formula results agreed well with the experimental results.