Experimental study on shear behavior of screw connections in CFS sheathing

Abstract

Monotonic and cyclic loading tests on 51 sets of sheathing-to-stud connections that covered four sheathing types were conducted, from which the failure modes and load-deformation relationships of the connections were obtained. Factors such as sheathing material, stud thickness, screw diameter, edge distance, sheathing orientation and loading mode were considered. The results showed that (1) for calcium silicate boards (CSB), specimens exhibited brittleness damage, whereas for the other sheathing types, obvious signs of damage were observed during testing; (2) compared to the cyclic test results, the shear capacities and non-deformabilities of the monotonic test specimens are higher; (3) edge distance has a much stronger effect on the shear capacity than screw diameter and stud thickness; with the increase in edge distance, the shear capacity under tension will be improved but no more than that under compression; and (4) compared with CSB, the loading direction has a minor effect on the shear capacities of the connections for the other sheathing types. A four-line degradation model was adopted to fit the skeleton curves of the connections, and a hysteretic model was established based on a pivot model and verified by a numerical method, showing good agreement between the simulated and test results. Finally, according to the experimental results, a series of connection deformation limits was suggested; moreover, during the shear strength design of the connections through the load resistance factor design method, the resistance factor can be assumed to be 0.62, whereas 0.59 should be replaced for those connections of CSB with a small edge distance.