Experimental analysis on small-scale finger-jointed specimens at elevated temperatures
Finger joints have to meet strength performance requirements for the use in structural engineered wood products such as glued-laminated timber beams (glulam). Among these, the thermal stability of the adhesive used in the finger joint is an important criterion to determine the suitability of the connection. The influence of adhesives on the load-carrying capacity of glulam beams and finger-jointed members can be assessed by large-scale fire tests; however, there are obvious benefits in using small-scale specimens tested at elevated temperatures as an alternative. In Europe, there is currently no small-scale test available to test the fire performance of adhesives in structural timber members. The work presented in this paper addresses this issue and was supported by members of a European standardisation committee to develop such a small-scale test. This paper presents, as a first step, the results of a series of tensile tests on small-scale finger-jointed specimens tested at elevated temperatures. The tests were performed with different types of adhesives which are currently also tested in large-scale fire tests. In the small-scale tests here, structural adhesives showed nearly no weaknesses with increasing temperature up to 140 °C. Further, MUF and PRF adhesives showed mostly wood failure even up to temperatures of 220 °C. In the next step of this investigation, the results obtained from the small-scale tests at elevated temperature will be compared to large-scale fire test results in order to find a possible link between both testing methods.
Fire performance of hardwood finger joints
This paper investigates the performance of Malaysian hardwood, dark red meranti finger joints in fire. Finger joints were prepared using two load-bearing type adhesives and tested in tension by means of a bench-scale fire test. They were tested in tension to replicate the failure of finger joints in tension layers of a glulam beam, which commonly occurs in a standard fire resistance test. Finger joints from softwood were also prepared and tested for comparison purposes. In addition, tensile tests at ambient temperature were conducted for both the hardwood and softwood finger joints in order to determine the approximate load level applied during the bench-scale fire tests. The time to failure, residual cross section and charring rate were determined and analysed. Results showed that the type of adhesive significantly influenced the time to failure. Furthermore, a lower residual cross-section was found in the finger joints bonded with phenol resorcinol formaldehyde (PRF) compared to the finger-jointed polyurethane (PUR) specimens. Therefore, PRF is better able to resist fire tests, has a higher residual strength and a longer time to failure compared to PUR.

 The effect of acetylation on bending strength of finger jointed beech wood (Fagus
 sylvatica L.)

Finger jointing is used in the wood industry for many years, yet it is only with the decline in the quality of resources that the interest in its use for furniture has increased. Nonstructural finger joints are used when strength is not of primary concern. The aim of this paper was to examine the effect of chemical modification on the bending strength of finger jointed Turkey beech wood used for external joinery in non-structural applications.