Flexural Strengthening of Old Timber Floors with Laminated Carbon Fiber–Reinforced Polymers
Publication: Journal of Composites for Construction
Volume 21, Issue 1
Abstract
A set of three old suspended timber floors were flexurally strengthened with carbon fiber–reinforced polymer (CFRP) strips in order to investigate the effectiveness of externally bonding FRP to their soffits. The specimens were from an old building and 740-mm-wide bands were transferred to the laboratory in order to be tested in a four-point bending test. One specimen was tested with no strengthening system and the results obtained were used as reference values for comparison with the specimens that were externally bonded and reinforced (EBR) with CFRP strips. Two similar EBR systems were studied: (1) keeping both ends of the CFRP strips free of any restriction (traditional technique), and (2) embedding both ends of the CFRP strips into the timber, thus providing a bonding anchorage of the strips (new technique). The installation of the new strengthening system comprises the opening of holes in the timber and the creation of a transition curve between the holes and the timber surface. This transition curve allows a smooth transition of the CFRP laminate between the hole and the timber surface, thus avoiding stress concentrations in this area. After the opening of the holes, the resin is applied inside the hole and on the beam surface, and then the CFRP laminate is mounted. The load-carrying capacity of the specimens, the rupture modes, and the strains and bond stress distributions within the CFRP-to-timber interface are presented. A nonlinear numerical simulation of the specimens based on the midspan cross-sectional equilibrium is also presented. The results showed that the use of the new strengthening system enhances the performance of the specimens when compared with the traditional strengthening system.
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Acknowledgments
The first author is grateful to Fundação para a Ciência e Tecnologia (FCT) for the partial financing of the work under the Research and Development Unit for Mechanical and Industrial Engineering (UNIDEMI) Strategic Project UID/EMS/00667/2013 and SFRH/BPD/111787/2015.
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Published In
Journal of Composites for Construction
Volume 21 • Issue 1 • February 2017
Copyright
©2016 American Society of Civil Engineers.
History
Received: Feb 1, 2016
Accepted: May 10, 2016
Published online: Jul 12, 2016
Discussion open until: Dec 12, 2016
Published in print: Feb 1, 2017
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