Abstract
A perfobond strip is a shear connector comprising a flat steel plate with a number of holes punched through it. Concrete flows through the holes forming dowels that act as shear keys, providing resistance in both vertical and horizontal directions. The perfobond strip is the shear connector proposed by Leonhardt in Germany, and the composite effect of steel and concrete is very high due to the shearing resistance of the concrete in the holes. In addition, the perfobond strip shear connector is recognized as having high fatigue strength. It is widely used as a validated shear connector in various steel-concrete hybrid civil engineering structures, since its shearing resistance and fatigue strength are larger and its constructability is better than those of other types of shear connectors such as headed stud shear connectors. Strength evaluation formulas for the design of these shear connectors have been proposed by various investigators around the world. A design formula was specified in the JSCE (Japan Society of Civil Engineers) Standard Specification for Hybrid Structures in 2009. In view of the excellent features of the perfobond strip, these shear connectors are expected to be increasingly applied to connections in building structures. However, connections in building structures are much smaller than those in civil engineering structures, so there is a need for a strength formula that accurately evaluates the force transfer mechanism, such as the restriction stress of the perfobond strip shear connections.
This paper proposes a new formulation for ultimate shear strength considering the restriction stress of concrete in the perfobond strip shear connections. The formulation provides ultimate shear strength by multiplying shear cracking strength by the ratio of ultimate shear strength to shear cracking strength. In the investigation, a regression formula for the relationship between the ratio and restriction stress is proposed based on a database including previous test results using no-cover simple-specimen loaded restriction force. This paper proposes a method of transforming the effect of restraining concrete around the steel plate hole by reinforced concrete cover and penetrating rebar, and transforming it into restriction stress in the ultimate shear strength formulation. Predictions from the proposed formulation almost agree with test results.
