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Evaluation of glue line shear strength of laminated timber structures using block and core type specimens

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Abstract

Monitoring and evaluation of glued laminated timber structures in service is essential to warrant its integrity, where non-destructive techniques play an important role. This paper describes the results obtained on glued laminated timber beams of maritime pine, with and without preservative treatment, and of spruce, exposed to natural outdoor environment as well as to artificial weathering. The assessment of glue lines’ shear strength was investigated through the extraction and testing of cores parallel and perpendicular to the glued lines and block shear specimens with 50 mm × 50 mm and 20 mm × 20 mm shear area. The results highlight the different performances of the various types of specimens tested, showing that the measured shear strength depends on the specimen size and that the size effect depends on the material strength giving a decreasing modification factor with the increase of strength in opposition to the constant factor suggested by standard EN 14080. They also show that shear testing of cores drilled perpendicular to the glued joints may be a promising tool in the assessment of glulam structures on site.

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Acknowledgements

The authors wish to thank Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology), for the PhD Grant (Number SFRH/BD/30310/2006) given to Florindo Gaspar.

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Authors and Affiliations

  1. Department of Civil Engineering, CDRSP, Polytechnic Institute of Leiria, Campus 2, Morro do Lena, Alto do Vieiro, 2411-901, Leiria, Portugal

    Florindo Gaspar

  2. Structures Behaviour Division, Laboratório Nacional de Engenharia Civil, Av. do Brasil, 101, 1700, Lisboa, Portugal

    Helena Cruz

  3. Department of Civil Engineering, CERIS, University of Lisbon, IST, Av. Rovisco Pais, 1049-001, Lisboa, Portugal

    Augusto Gomes

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  1. Florindo Gaspar
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  2. Helena Cruz
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  3. Augusto Gomes
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Correspondence to Florindo Gaspar.

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Gaspar, F., Cruz, H. & Gomes, A. Evaluation of glue line shear strength of laminated timber structures using block and core type specimens. Eur. J. Wood Prod. 76, 413–425 (2018). https://doi.org/10.1007/s00107-017-1217-4

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  • DOI: https://doi.org/10.1007/s00107-017-1217-4

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