Evaluation of the mechanical properties of Douglas-fir and Japanese cedar lumber and its structural glulam by nondestructive techniques

Published Date
Received 13 March 2006, Revised 6 November 2006, Accepted 20 November 2006, Available online 2 January 2007.

Author
Te-HsinYanga. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.Song-YungWanga. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.Cheng-JungLinb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspace. Author links open the author workspace.Ming-JerTsaia. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspaceOpens the author workspace

a

School of Forestry and Resource Conservation, College of Bioresource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC

b

Division of Forest Utilization, Taiwan Forestry Research Institute, Taipei, Taiwan, ROC

https://doi.org/10.1016/j.conbuildmat.2006.11.012

Abstract

The objectives of this study were to investigate the effects of the configuration of the lamina on the bending properties of glulam made from Douglas-fir and Japanese cedar lumber. By using a visual grading method according to CNS 14631 and nondestructive evaluation techniques (including the ultrasonic wave technique, transverse vibration test and static bending test), lamina having both higher dynamic MOE and static MOE were chosen for the outside layers, in order to manufacture homogeneous and heterogeneous grade structural glulam lamina, with higher strength properties. The degrees of correlation, obtained from the different nondestructive testing methods, were then analyzed. The results indicated that the DMOEv, DMOEt and MOE values for both Douglas-fir and Japanese cedar lumber showed a decreasing order as follows: construction grade > standard grade > utility grade. It was also found that the transverse vibration test is a better nondestructive method of evaluating sawn lumber. The different configurations of the lamina within glulam can be used to fabricate glulams with different grades of bending strengths. The predicted values of glulam Eb(sp), were higher than those of the experimental values Eb(sc). Moreover, the value of Eb(sc)increased linearly with an increasing MOE of the outside layers of lamina (e3).

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0950061806003096

Study of glulam beams pre-stressed with pultruded GRP

Published Date
Received 23 January 2004, Accepted 18 March 2005, Available online 24 August 2005.

Author
Z.W.GuanOpens the author workspaceOpens the author workspace. Author links open the author workspace.P.D.Rodd. Author links open the author workspace.D.J.Pope

School of the Environment, University of Brighton, Moulsecoomb, Brighton BN2 4GJ, United Kingdom

https://doi.org/10.1016/j.compstruc.2005.03.021

Abstract

Improvement of the load carrying capacity of glulam beams by the addition of reinforcement is now common practice. Recently it has been demonstrated that pre-stressing of beams using pultruded glass fibre reinforced plastic (GRP) tendons provides an available alternative due to the compatibility of the two materials and the low losses of pre-stress. This paper describes a finite element based model which was validated against test results and then used to investigate bond stress between a pre-stressed GRP tendon and the adjacent timber. Parametric studies were also undertaken to evaluate the effects of tendon thickness, beam span and the pre-tension force on the structural behaviour of beams.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0045794905002373

Reliability analysis of a glulam beam

Published Date
Available online 11 September 2006.

Author
TomiTorattia. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspaceOpens the author workspace. Author links open the author workspace.SimonSchnablb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspace. Author links open the author workspace.GoranTurkb. Numbers and letters correspond to the affiliation list. Click to expose these in author workspaceOpens the author workspace

a

VTT Technical Research centre of Finland, P.O. Box 1000, FI-02044 VTT, Finland

b

University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana, Sloven

https://doi.org/10.1016/j.strusafe.2006.07.011

Abstract

The present case study is an example of the use of reliability analysis to asses the failure probability of a tapered glulam beam. This beam is part of a true structure built for a super market in the town of Kokemäki in Finland. The reliability analysis is carried out using the snow load statistics available from the site and on material strength information available from previous experiments. The Eurocode 5 and the Finnish building code are used as the deterministic methods to which the probabilistic method is compared to. The calculations show that the effect of the strength variation is not significant, when the coefficient of variation of the strength is around 15% as usually assumed for glulam. The probability of failure resulting from a deterministic design based on Eurocode 5 is low compared to the target values and lower sections are possible if applying a probabilistic design method. In fire design, if a 60 min resistance is required, this is not the case according to Eurocode 5 design procedures, a higher section would be required. However, a probabilistic based fire analysis results in bounds for the yearly probability of failure which are comparable to the target value and to the values obtained from the normal probabilistic based design.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0167473006000452

Advanced wood engineering: glulam beams

Published Date
Received 9 January 2002, Revised 20 May 2004, Accepted 24 May 2004, Available online 19 July 2004.

Author
Camille A.IssaOpens the author workspaceOpens the author workspace. Author links open the author workspace.ZiadKmeid

Department of Civil Engineering, Lebanese American University, Byblos, Lebanon

https://doi.org/10.1016/j.conbuildmat.2004.05.013

Abstract

The main objective of this experimental study is the determination of the flexural properties of reinforced and unreinforced glued-laminated beam. Why reinforcing glulam beam? Reinforced glulam beams cost less because the use of reinforcement will reduce the need of a top grade laminate on the extreme tension face (less high grade material can be used); moreover the volume of wood is reduced. Also, reinforced glulam beams have lower product variability, they are not affected by natural growth characteristics, and the manufacture of reinforcement is consistent and controlled.

Two types of reinforcement were investigated: steel plate and carbon fiber reinforced polymer (CFRP). The wood part of all the beams were made by laminating three wood beams of 6 by 3.6 by 176 cm. The unreinforced beams are made only from wood having a finished dimension equal to 6 by 11 by 176 cm. The steel reinforced beams were glulam wood beams fully covered on one side using steel plate of thickness equal to 1.5 mm.The CFRP reinforced beams were glulam wood beams covered with CFRP of thickness of 1.2 mm and width of 5 cm and the length of 176 cm.

The results indicate that the behavior of reinforced beams is totally different from that of unreinforced one. The reinforcement has changed the mode of failure from brittle to ductile and has increased the load-carrying capacity of the beams.

For further details logo website :
http://www.sciencedirect.com/science/article/pii/S0950061804001199