Testing, numerical and analytical modelling of self-drilling screw connections between thin steel sheets in shear

The shear behaviour of self-drilling screw connections between thin steel sheets is investigated via experimental testing, numerical and analytical modelling in this paper. A total of nineteen sets of single-lap joint specimens with self-drilling screw connections were tested to failure under shear. The full force versus deformation curves were recorded, and three typical failure modes were obtained and were shown to be closely related to the ratio of the screw diameter to the sheet thickness. Prior to testing, constitutive responses of the employed thin steel sheets were acquired from tensile coupon tests, and were further represented by a three-stage model including an elastic branch, a plastic branch described by the Ludwik equations, and a damage branch defined by the Johnson-Cook model and the linear accumulation damage evolution law. Advanced finite element (FE) models of the screw connections were developed and validated against the obtained shear test results, and a parametric study on the influences of the sheet thickness and the screw diameter was carried out afterwards. Based on the obtained test and FE results, a new prediction model for the shear deformation behaviour of self-drilling screw connections was proposed and calibrated. The newly proposed prediction model was further introduced into the numerical models of the cold-formed box girders fabricated by self-drilling screws, the applicability of which was verified by the close agreement with the available experimental evidence.