Mode Cross-Over and Ductility of Dowelled LVL and CLT Connections under Monotonic and Cyclic Loading

Abstract

This paper presents an experimental study on dowelled connections in Cross-Laminated Timber (CLT) and Laminated Veneer Lumber (LVL) using ϕ20 mm mild steel dowels and internal steel plates. Connections designed to fail in brittle row shear and group tear-out were tested under monotonic loading to assess the validity of analytical models from literature and code provisions. Connections designed to provide non-linearity before failure and thus produce ductility were tested under both monotonic and cyclic loading to study the influence of cyclic loading on ductility and the possibility of mode cross-over. It was found that cross layers in CLT improve ductility. Furthermore, mode cross-over from ductile response to brittle failure was observed in both CLT and LVL connections. Nevertheless, a good amount of ductility was achieved in all layouts (except the LVL connections designed for group tear-out failure) before cross-over to brittle failure occurred.

Analytical Derivation and Experimental Verification of Overstrength Factors of Dowel-type Timber Connections for Capacity Design

“…For a detailed step-by-step procedure and example calculations refer to Ottenhaus et al 2018d. Ottenhaus et al 2016).…”

“…Eurocode 5 (2004) uses the effective bending yield moment M eff = 0.3d 2.6 f u to calculate the fastener yield moment, M y , based on the assumption that full plasticisation of the cross sections of stocky fasteners is hardly achieved in timber connections (Blaß et al 2001). However, as Stehn and Johnsson (2002) pointed out, this is due to timber splitting which leads to mode cross-over from a ductile response to brittle failure of the Stehn and Johnsson (2002), Novis et al (2016), andOttenhaus et al (2018a).…”

“…Nail bending tests were conducted to determine the nail yield moment from which the yield strength was derived as f y = 530 MPa. More information on the nailed hold-down connection tests can be found in Ottenhaus et al 2016.…”

Hyperelastic hold-down for cross-laminated timber shear walls

“…Ottenhaus et al [47,48] characterized the performance of dowel-type connections as HD for mass timer products under monotonic and cyclic loading. The connection was installed using internal steel plates inserted into slots of CLT panels, c.f.…”

“…Dowel-type connection with the internal steel plate: (a) sketch, (b) test set-up, and (c)spacing of the fasteners on the bottom side of the test specimen[47] "With permission form ASCE".…”