Experimental investigation of the axial strength of glued-in rods in cross laminated timber

Boris Azinović,Tomaž Pazlar,Erik Serrano,Miha Kramar

doi:10.1617/s11527-018-1268-y

Boris Azinović, Tomaž Pazlar + Show 2 more

Open Access

https://doi.org/10.1617/s11527-018-1268-y

Copy DOI

Abstract

This paper presents results from an experimental assessment of glued-in rods in cross laminated timber (CLT). For the purposes of the study more than 60 pull–pull tests were performed, where the specimens varied in terms of bonded-in length (from 80 to 400 mm), rod diameter (16–24 mm) and rod-to-grain angle (parallel and perpendicular). Several different failure modes that are not common for other applications of glued-in rods (e.g., a failure between CLT layers) were obtained for the analysed CLT specimens. It was found that these failure mechanisms can substantially influence the obtained ultimate tension loads. At the end, the experimental results were compared with empirical and semi-empirical equations for estimating the pull-out strength of glued-in rods in structural timber and glulam. The comparison showed that most of the existing equations overestimate the ultimate tension loads for specimens with the rod parallel to the grain and underestimate the ultimate tension load for specimens with the rod perpendicular to the grain. The results vary because the possible CLT failure modes were not included in previous studies. Further studies are proposed to improve the equations for glued-in rods in CLT.

Highlights

Glued-in rods in timber elements can be considered as hybrid connections, since they involve three different elements: the timber, the rod connector and the adhesive [1]
The primary objective of this research was to analyse the mechanical behaviour of glued-in rods in cross laminated timber (CLT) and how it differs from the behaviour of glued-in rods in structural timber, glulam and laminated veneer lumber (LVL)
The experiments showed that the behaviour of the joints varies greatly depending on the bonded-in length and the rod diameter

Summary

Introduction

Glued-in rods in timber elements can be considered as hybrid connections, since they involve three different elements: the timber, the rod connector and the adhesive [1]. In many cases these joints outperform dowel-type mechanical fasteners. Glued-in rods are appropriate to connect the CLT with other structural elements of different materials (e.g., vertical joints between CLT walls and steel beams, joints between CLT walls and concrete elements, etc.). In this way glued-in rods can be a solution for connecting different structural elements into hybrid structural systems.

Objectives

Results

Conclusion