Withdrawal of pairs of threaded rods with small edge distances and spacings

Abstract

An experimental investigation on withdrawal of pairs of screwed-in threaded rods embedded in glued-laminated timber elements is presented in this paper. Specimens with varying angles between the rod axis and the grain direction (α= 15, 30, 60, 90°) and 2 different configurations with respect to edge distances and spacings were tested. The diameter and the embedment length of the rods were 20 mm and 450 mm, respectively. The threaded rods were embedded in a row perpendicular to the plain of the grain. The edge distances and spacings were smaller than the minimum requirements according to Eurocode 5. The withdrawal capacity of pairs of rods was compared to the withdrawal capacity of single rods and the effective number, nef, was found to be in the range 1.72-1.94, despite the small edge distances and spacings. Based on the obtained experimental results, a simple approximating expression was derived for nef. An analytical model based on Volkersen theory with an idealized bi-linear constitutive relationship was used to estimate the withdrawal capacity and stiffness. The analytical estimations were in good agreement with the experimental results. Finally, the withdrawal stiffness was estimated by use of finite element simulations. The numerical estimations for the withdrawal stiffness were also in good agreement with the experimental results.

Research status of glued-in rods connections in wood structures

“…The GB group's load capacity was similar to the theoretical value, but the GS group's load capacity was lower than the theoretical predicted value, indicating that the GIR connection was not suitable for high strength reinforcement. a: Bending bearing capacity; b Mean capacities of specimens with single rods as measured experimentally [114] The differences in bonding mechanical properties of the GIR connections inserted with various numbers of rods are summarized and compared in Table 7. Gattesco and Gubana [115] carried out an experimental study on different glued-in bars connections with 2-4 rods.…”

“…In conclusion, compared to a single rod connection, when brittle damage occurs, the failure of one rod may cause the failure of the entire connection even if the load does not undergo plastic redistribution. Stamatopoulos and Malo [117] conducted pullout tests on 324 glued-laminated timber specimens with two threaded rods to evaluate the interaction effects (group effect), and the effective number of rods was 1.72-1.94. Gonzalez et al [118] investigated the tensile strength of laminated timber with multiple glued-in steel rods (two, three, and four).…”

Pull-out Behaviour of Axially Loaded Screwed-in Threaded Rods Embedded in CLT Elements: Experimental Study

“…Early in 2006, Nakatani et al [21] developed a moment-resisting joint system using screwed-in threaded rods (lagscrewbolt) and showed good performance. Stamatopoulos et al [3][4][5]22,23] evaluated the withdrawal capacity and stiffness of threaded rods screwed-in glulam timber through experimental, numerical and theoretical methods. The parameters include embedment length and rod-to-grain angles.…”

Experimental static and seismic behaviour of glulam beam-to-column connection with screwed-in threaded rod joints

“…Considerable research on the withdrawal behaviour of screwed-in threaded rod joints has been conducted. There have been experimental, numerical, and theoretical investigations of withdrawal capacity and stiffness of threaded rods screwed-in glulam timber (Stamatopoulos and Malo 2015;Stamatopoulos and Malo 2016;Stamatopoulos and Malo 2018;Stamatopoulos and Malo 2020;Yang et al 2021). A model based on non-linear fracture mechanics has been used to estimate the withdrawal capacity of screws embedded in glulam (Jensen et al 2012).…”