Experimental and Numerical Study on Shear Performance of Pitched Screws in Wood-Concrete Composite Beam with Wooden Partitions

Wooden partitions are extensively used as formwork for pouring concrete in wood-concrete composite beams, especially in the restoring of wood structures. However, limited research has been conducted on the shear properties of pitched screw connectors in wood-concrete composite beams with wooden partitions. Therefore, this study investigated the shear performance of pitched screws in wood-concrete composite beams with wooden partitions through push-out tests and finite element analysis. The test results revealed that the failure mode of pitched screws was characterized by the pulling failure of the screws under tensile-shear action. The finite element analysis accurately predicted the failure mode, stress distribution, and load-slip behavior of pitched screws. Furthermore, the effects of the screw embedding angle, wooden partition thickness, concrete strength, and the length-diameter ratio of the screw were investigated through parametric analyses. It was found that when the screw diameter was 12 mm, the shearing capacity of the pitched screws with embedding angles of & PLUSMN;45 & DEG;, & PLUSMN;60 & DEG;, and & PLUSMN;75 & DEG; decreased by 3.9%, 11.9%, and 26.9%, respectively, compared to the screws with an embedding angle of & PLUSMN;30 & DEG;. The shearing capacity of pitched screws improved with the increase in the concrete strength and length-diameter ratio of the screw. However, the improvement in shearing capacity became less significant as the concrete strength and length-diameter ratio of the screw increased. Moreover, an increase in wooden partition thickness reduced the shearing capacity of pitched screws.