Ductility of shear stud

Recently one of our Indian clients asked the question about the reduction of area of shear stud, and he only knows the elongation of shear stud, the two parameters belong to the ductility of shear stud. This post will talk this topic.

The shear studs(also called shear connectors) are used on steel construction building, mainly because the shear studs have better ductility which is a desirable property for structural materials to resist the earthquake. In the ISO13918 standard, it only requires the elongation of shear studs(≥15%), and there is not the requirement for reduction of area, this is the reason why most guys don’t know the parameter. But in the AWS D1.1 standard, the elongation for Type A is 17%(in 2 in.) and 14%(in 5x dia.), for Type B is 20%(in 2 in.) and 15%(in 5x dia.) which is mainly for shear studs. The reduction of area for Type A and Type B both are 5o%.

Ps: If some guys want to know the main standards for shear studs, please see our former post: Comparison of shear connector for main standards

Definition of ductility of shear stud

Ductility is defined as the ability of the shear stud to deform plastically before fracturing. Its measurement is of interest to those conducting shear stud forming processes, to designers/engineers of steel structures, and to those responsible for assessing the quality of the shear stud as it is being produced.

Ductility of shear stud

How to measure ductility of shear stud?

There are two parameters: Elongation and reduction of area.

Elongation and reduction of area measure different types of shear stud behavior. Provided the gage length is not too short, elongation is chiefly influenced by uniform elongation and thus is dependent on the strain-hardening capacity of the shear stud. Reduction of area is more a measure of the deformation required to produce fracture and its chief contribution results from the necking process.
Because of the complicated stress state in a neck, values of reduction of area are dependent on specimen geometry and deformation behavior, and they should not be taken as true material properties. However, reduction of area is the most structure-sensitive ductility parameter, and as such it is useful in detecting quality changes in a material.
Elongation of shear stud

Elongation (%) = 100 x ∆L/Lo

where Lo is the original gage length.

Reduction of Area (%) = 100 x (Ao – Af)/Ao

where Ao is the original cross-sectional area

Ps: If some guys don’t know about the elongation of shear stud, please see our post: How to test mechanical properties of shear stud?

To help to understand the reduction of area of shear stud, please see the image.

Reduction for area of shear stud_Sino Stone

In the testing sample,

reduction of area=100*(A0-Af)/A0=100*(πR2-πr2)/πR2=100*(R2-r2)/R2=100*(0.42-0.2652)/0.42=56