A New Bonding Technique for the Rehabilitation of Old Timber Floors with CFRP Composites

Citation:
A New Bonding Technique for the Rehabilitation of Old Timber Floors with CFRP Composites, Biscaia, Hugo, Chastre Carlos, Cruz David, and Franco Noel , 41th IAHS Word Congress of Housing. Sustainability and Innovation for the Future, 13-16 September , Albufeira, Portugal, p.10, (2016) copy at https://docentes.fct.unl.pt/cmcr/publications/new-bonding-technique-rehabilitation-old-timber-floors-cfrp-composites

Date Presented:

13-16 September

Abstract:

Despite the number of applications with Carbon Fiber Reinforced Polymers (CFRP) have been grown in civil constructions, the studies available in the literature dedicated to the strengthening of old timber beams are very rare. This paper analyses the bending behaviour of old suspended timber floors flexurally-strengthened with CFRP laminates. A new bonding technique developed by the authors is presented which mainly consists on the embedding of both CFRP ends into the core of the timber beams. Differences between the traditional strengthening, i.e. Externally Bonded Reinforcement (EBR), and the new bonding technique are reported. A timber pavement without any CFRP laminate bonded to its soffit was also considered and the results were used as reference values for comparison with the strengthened specimens. The results revealed that the CFRP laminate used for the flexurally-strengthened of the specimen according to the EBR technique reached only 27.2% of the rupture strain of the CFRP laminate whereas the new bonding technique was capable to prevent the premature debonding of the CFRP from the timber substrate and the rupture of the CFRP laminate was observed. Furthermore, the strain distributions in the CFRP laminates and the bond stresses within the CFRP-to-timber interfaces were affected when the new technique was used. For the sake of better understanding the rupture modes observed, a numerical approach was developed which allowed us to conclude that, until the collapse of the beams, the timber never reached its yielding point and the collapse were mainly due to the poor quality of the timber (e.g. quantity of knot, cracks and irregular geometries) and the low shear capacity of the beams.

Notes:

REFERENCES[1] E.J. Biblis “Analysis of wood-fiberglass composite beams within and beyond the elastic region” Forest Product Journal, vol. 15, no. 2, pp. 81-88, 1965.[2] N. Plevris and T. Triantafillou “FRP-Reinforced wood as structural material” Journal of Materials in Civil Engineering, vol. 4, no. 3, pp. 300-317, 1992.[3] B. Mu, H. Wu, A. Yan, K. Warnemuende, G. Fu, R. Gibson, and D. Kim “FEA of Complex Bridge System with FRP Composite Deck” Journal of Composites for Construction, vol. 10, no. 1, pp. 79-86, 2006.[4] Y.J. Kim and K.A. Harries “Modeling of timber beams strengthened with various CFRP composites” Engineering Structures, vol. 32, no. 10, pp. 3225-3234, 2010.[5] S. Hamel, J. Hermanson and S. Cramer “Predicting the Flexure Response of Wood-Plastic Composites from Uni-Axial and Shear Data Using a Finite-Element Model” Journal of Materials in Civil Engineering, vol. 26, no. 12, 04014098, 2014.[6] G.M. Raftery and P.D. Rodd “FRP reinforcement of low-grade glulam timber bonded with wood adhesive” Construction and Building Materials, vol. 91, pp. 116-125, 2015.[7] J. Wan, S. Smith, P. Qiao and F. Chen “Experimental investigation on FRP-to-timber bonded interfaces” Journal of Composites for Construction, vol. 18, SPECIAL ISSUE: 10th Anniversary of IIFC, A4013006, 2014.[8] H.C. Biscaia, D. Cruz and C. Chastre “Analysis of the debonding process of CFRP-to-timber interfaces” Construction and Building Materials, vol. 113, pp. 96-112, 2016.[9] D. Cruz “Reforço de elementos estruturais de madeira com materiais compósitos de matriz polimérica” M.Sc. thesis, Nova Univ. of Lisbon, Lisbon, Portugal, 2015.[10] T. Carvalho, C. Chastre, H.C. Biscaia and R. Paula “Flexural behaviour of RC T-beams strengthened with different FRP materials” in 3rd fib International Congress, Washington D.C., United States of America, May 29-June 2, 2010.[11] P. Faustino and C. Chastre “Analysis of load–strain models for RC square columns confined with CFRP” Composites Part B: Engineering, vol. 74, pp. 23-41, 2015.[12] LNEC M1 “Madeira para construção. Especificação de Madeiras para estruturas” Lisboa, 1997. (in Portuguese)[13] LNEC M4 “Madeira para construção. Casquinha” Lisboa, 1997. (in Portuguese)[14] R. Kliger, M. Al-Emrani, M. Johansson and R. Crocetti “Strengthening glulam beams with steel or CFRP plates” in Asia-Pacific Conference on FRP in Structures, December 12-14, Hong Kong, China, 2007.

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