Withdrawal Performance of Nails and Screws in Cross-Laminated Timber (CLT) Made of Poplar (Populus alba) and Fir (Abies alba)

Abstract

Cross-laminated timber (CLT) can be used as an element in various parts of timber structures, such as bridges. Fast-growing hardwood species, like poplar, are useful in regions where there is a lack of wood resources. In this study, the withdrawal resistance of nine types of conventional fasteners (stainless-steel nails, concrete nails and screws, drywall screws, three types of partially and fully threaded wood screws, and two types of lag screws), with three loading directions (parallel to the grain, perpendicular to the surface, and tangential), and two layer arrangements (0-90-0° and 0-45-0°) in 3-ply CLTs made of poplar as a fast-growing species and fir as a common species in manufacturing of CLT was investigated. Lag screws (10 mm) displayed the highest withdrawal resistance (145.77 N), whereas steel nails had the lowest (13.13 N), according to the main effect analysis. Furthermore, fasteners loaded perpendicular to the grain (perpendicular to the surface and tangential) had higher withdrawal resistance than those loaded parallel to the grain (edge). In terms of the layer arrangement, fasteners in CLTs manufactured from poplar wood (0-45-0°) had the greatest withdrawal resistance, followed by CLTs manufactured from poplar wood in the (0-90-0°) arrangement, and finally, those made from fir wood in the (0-90-0°) arrangement. The fastener type had the most significant impact on the withdrawal resistance, so changing the fastener type from nails to screws increased it by about 5–11 times, which is consistent with other studies. The results showed that poplar, a fast-growth species, is a proper wood for manufacturing CLTs in terms of fastener withdrawal performance.

Effect of Nail Models and Diameters on the Withdrawal Resistance of Allantoma decandra (Lecythidaceae) Wood

“…All nail models and diameters inserted into the tangential faces required higher loads to be withdrawn than those inserted into the radial faces, which can be explained by the higher number of dense parenchyma layers pierced by the nails [25]. In this direction, there is greater interaction between the wood tissues and the nail shanks, resulting in greater withdrawal resistance and consequently greater damage to the wood´s surface [17]. However, after applying a factorial ANOVA, no statistically significant difference was found between the mean results obtained for the radial and tangential faces (P value = 0.125).…”

“…Due to the recent increase of environmental awareness and the ability of wood to embed carbon, timber constructions have emerged worldwide as an alternative for mitigating climate change while acting as a limitless carbon sink [15][16][17] . The "massive timber construction movement" is based on various wood engineered products and building technologies, such as: glued laminated timber (glulam), cross laminated timber (CLT), wood-frame and post-frame [5,16].…”

Effect of Wood Densification and GFRP Reinforcement on the Embedment Strength of Poplar CLT

“…Poplar is a fast-growing tree, which is advantageous in nations with a wood supply shortage. Several studies have examined the CLT properties of fast-growing timber species [23][24][25][26][27][28][29].…”

10th Hardwood Conference Proceedings

“…Over the past few decades, many studies have been conducted to evaluate the suitability of Poplar as a construction material. These studies have primarily focused on the mechanical characterization and mechanical properties of the CLT (Kramer et al 2014, Rostampour Haftkhani & Hematabadi 2022; bonding performance of poplar CLT (Weidman 2015); nail and screw withdrawal resistance of Poplar CLT (Abdoli et al 2022). However, its suitability with species combination for manufacturing mixed species/hybrid CLT (Wang et al 2014, Hematabadi et al 2021) was also examined.…”