Behaviour of screw shear connections between oriented strand board and cold-formed steel sections under ambient and post-heating conditions: An experimental and analytical investigation

This paper presents an experimental and numerical investigation of the push-out behaviour of shear connectors in oriented strand board (OSB) and cold-formed steel (CFS) composite beams under ambient and post-heating conditions. The results of this research are used to evaluate the level of accuracy of existing Eurocode 5 design equations for the prediction of failure mode and failure load of shear connectors for ambient temperature design and for post-fire assessment. Ambient temperature and uniform temperature post-heating tests were carried out on OSB material under compression and on OSB-steel shear connectors under push-out loading. The compressive mechanical tests were used to obtain residual mechanical properties of OSB after heating to different temperatures, and to provide shear connector behaviour for the assessment of the Eurocode 5 design method and for validation of a numerical simulation model. The 16 push-out tests comprised two temperatures (ambient & 200 °C), two screw diameters (3.5 mm & 5.5 mm), and two steel section thicknesses (1.2 mm & 2.4 mm). It has been found that the existing Eurocode 5 design method is particularly inaccurate in predicting the bearing resistance of shear connectors with thin-steel plates. The Eurocode 5 method of using a fixed value of 0.25 to account for inclination of the steel screw was also found to be inaccurate. Through a systematic numerical parametric study, modifications have been proposed to improve the Eurocode calculation method. The revised method was found to provide greatly improved predictions of the new test results of this research for both ambient and uniform post-heating tests and previous test results by others at ambient temperature.