The experimental and numerical investigation on withdrawal resistance of ringed shank nails inserted into glued laminated timber

Buildings with glued laminated timber (glulam) structural elements typically utilize threaded nails, such as helically threaded, and ringed shank nails, in their connections. The withdrawal capacity of nails is essential for designing connections secondary beam-to-primary beam or beam-to-column connections using joist hangers and aluminum T-profiles in mass timber buildings. However, there is limited information on this mechanical property in the literature and standards regarding ringed shank nails. In this context, the present paper aims to numerically and experimentally study the withdrawal behavior of ringed shank nails inserted into glulam. Withdrawal tests were conducted to evaluate the withdrawal strength and failure modes of glulam samples made from Eucalyptus grandis and Pinus spp. in the longitudinal, radial, tangential and glueline directions. In addition, a numerical study was realized using finite element software ABAQUS/CAE to simulate the mechanical behavior of the withdrawal of these nails. The withdrawal strength was higher in the normal directions than in the longitudinal direction for both timber species. For Eucalyptus glulam, the difference between the perpendicular and longitudinal direction was at least 113.79%, whereas for Pinus spp. glulam, the corresponding difference was at least 106.52%. The timber species influenced the withdrawal strength of ringed shank nails inserted into glulam. The normalized withdrawal strength (MPa.m3/kg) of Eucalyptus glulam was at least 37.5% higher than that of Pinus spp. glulam in normal direction, whereas the corresponding difference in the longitudinal direction was 30%. The experimental load-displacement curves were replicated in the numerical model, which was developed using a cohesive damage model to simulate the interaction between the nail shank and the timber surface. Therefore, the cohesive model can be employed in numerical simulations of ringed shank nail withdrawal to assess the mechanical behavior of joints in timber structures that incorporate these fasteners.