Performance of Glued-Laminated Timbers with FRP Shear and Flexural Reinforcement
Publication: Journal of Composites for Construction
Volume 15, Issue 5
Abstract
Glued-laminated wood beams (glulams) have low allowable shear stresses relative to competitive engineering wood products such as parallel strand lumber and laminated veneer lumber. For heavily loaded applications such as garage door headers, the lower shear allowable stresses typically necessitate the use of larger glulam members relative to other engineered lumber. This paper reports on experimental research aimed at increasing the shear capacity of glulams. To increase the shear strength, a series of fiber-reinforced polymeric (FRP) pins are inserted into holes drilled transversely across the plies of the glulam. These pins are epoxy-bonded into place after the glulam has been produced. The test results show that the shear strength scatter in the pinned set of glulams is significantly reduced as compared to the unpinned specimens. Two- and three-parameter Weibull estimates of the service-level allowables increases between 40% and 100% for specimen sets reinforced by the FRP pins. The transverse reinforcing scheme also shows promise for aiding in engagement of composite flexural reinforcement plies into the laminate stack. Previous research has shown that the bonding between wood and FRP plies has potential long-term durability problems. Therefore, the pinning technology reported on in this work shows promise for providing a means for direct engagement (through bearing of the pins) of the FRP plies to the wood plies. This behavior has been demonstrated though the testing of larger-scale specimens with both transverse shear reinforcements and longitudinal FRP plies. The reinforcing strategies show potential structural and economic advantages, especially when the FRP is coupled with low-grade, low-value finger-jointed lumber.
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Acknowledgments
The writer would like to acknowledge the support of the Georgia Traditional Industries program, , for their financial support and guidance of this research. The lumber used in this study was provided by Langdale Forest Products of Valdosta, Georgia. The following students are acknowledged for their work in fabricating and testing the small-scale specimens—Wade Burch—and large-scale specimens—Bradley Dolphyn, Steven Hensey, and Jonathan Schwartz.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 15 • Issue 5 • October 2011
Pages: 861 - 870
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Jun 20, 2010
Accepted: Jan 12, 2011
Published online: Jan 14, 2011
Published in print: Oct 1, 2011
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