The effect of fissures on the strength of structural timber

Miguel Esteban; Francisco Arriaga; Guillermo Íñiguez; Ignacio Bobadilla; Raquel Mateo

doi:10.3989/mc.2010.48208

Authors

Miguel Esteban Universidad Politécnica de Madrid, ETSI Montes
Francisco Arriaga Universidad Politécnica de Madrid, ETSI Montes
Guillermo Íñiguez Asociación de Investigación de las Industrias de la Madera, Madrid
Ignacio Bobadilla Universidad Politécnica de Madrid, EUIT Forestal
Raquel Mateo Asociación de Investigación de las Industrias de la Madera, Madrid

DOI:

https://doi.org/10.3989/mc.2010.48208

Keywords:

Timber, Mechanical Properties, Characterization, Drying Fissure

Abstract

Detailed measurements of drying fissures were carried out on 28 pieces of gross cross-section structural Scots pine timber. Different parameters have been proposed to measure their magnitude: length, depth, thickness and slope of grain, as well as an index of area in the neutral axis plane (ratio of effective to total surface). The parameters of fissures have been related to bending strength, shear strength, modulus of elasticity and rupture energy obtained from mechanical tests, considering whether rupture is due to bending or shear. All of the fissures observed allows to classify the pieces as MEG according to the UNE 56544 standard. To quantify the magnitude of fissures the index of areas is proposed, while mechanical properties can be quantified by rupture energy. Analysis of the results does not show any relation between the fissures analyzed and the mode of failure, their magnitude and mechanical properties..

Downloads

Download data is not yet available.

References

(1) DIN 4074. Sortierung von Holz nach der Tragfähigkeit (Strength grading of wood).

(2) BS 4978. Visual strength grading of softwood. Specification for visual strength grading of softwood.

(3) NF B 52001. Règles d’utilisation du bois en structure.

(4) INSTA 142. Nordic visual stress grading rules for timber.

(5) UNE 56544. Clasificación visual de la madera aserrada para uso estructural: madera de coníferas (Visual stress grading of structural sawn timber: coniferous.

(6) Salomon. Charpente traditionelle: qualité et classement des bois de forte section. CTBA Info nº 85 (2000). Pp 9-14.

(7) UNE-EN 844-9. Madera aserrada y madera en rollo. Terminología. Parte 8: Términos relativos a las singularidades de la madera en rollo (Round and sawn timber. Terminology. Part 9: Terms relating to features of sawn timber.)

(8) Newlin, J.A. Shear in checked beams. Amer. Ry. Engin. Assoc. Bull. 364. 1001-1004, illus. (1934)

(9) Newlin, J.A., Heck, G.E., and March, H.W. New method of calculating longitudinal shear in checked wooden beams. Amer. Soc. Mech. Engin. Trans., 56: 739-744, illus. (1934)

(10) Barret, J.D. and Foschi, R.O. Shear strength of uniformly loaded dimension lumber. Canadian Journal of Civil Engineering, 4, 86 (1976). doi:10.1139/l77-009

(11) ASTM D245 Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber. American Society for Testing and Materials. 1971. ASTM Standards, Vol. 16. Philadelphia, PA.

(12) Ido, H., Nagao, H. and Kato, H. Evaluation of shear strength of timber by some non-destructive methods. Proceedings of the 14th International Symposium on Nondestructive Testing of Wood. University of Applied Sciences Eberswalde, Germany. Hannover may 2- 4, 2005. (2005) Pp. 415-420.

(13) Íñiguez, G. Clasificación mediante técnicas no destructivas y evaluación de las propiedades mecánicas de la madera aserrada de coníferas de gran escuadría para uso estructural (Grading by non destructive techniques and assessment of the mechanical properties of large cross section coniferous sawn timber for structural use). Doctoral Thesis. Universidad Politécnica de Madrid, ETS de Ingenieros de Montes. 223 p (2007). PDF file: http://oa.upm.es/415.

(14) Pedrotti, P., Paganini, F and Del Senno, M. Longitudinal boring of beams. Xylon International, jul-aug (2000). Pp 72-75.

(15) Klöck, W. Statistical analysis of the shear strength of glued laminated timber based on full-size flexure tests. Otto-Graf-Journal, Vol. 16 (2005), pp. 225-243.

(16) Aicher, S., Hill-Langer, G. and Ringger, T. Non-Destructive detection of longitudinal cracks in glulam beams. Otto-Graf-Journal, Vol. 13, (2002) pp. 165-181.

(17) Esteban, M. Determinación de la capacidad resistente de la madera estructural de gran escuadría y su aplicación en estructuras existentes de madera de conífera (Determination of the load carrying capacity of large cross section structural coniferous timber on existing structures). Doctoral Thesis. Universidad Politécnica de Madrid, ETS de Ingenieros de Montes. 365 p. (2003) PDF file: http://oa.upm.es/1404.

(18) Arriaga, F., Esteban, M. y Relea, E. Evaluation of the load carrying capacity of large cross section coniferous timber in standing structures. Evaluación de la capacidad portante de piezas de gruesa escuadría de madera de conífera en estructuras existentes. Materiales de Construcción (mater construcc). Vol. 55, nº 280 (2005), pp: 43-52.

(19) Mateo, R. Análisis de la influencia de las fendas en la capacidad resistente de piezas de madera (Analysis of influence of fissures in load carrying capacity of timber pieces). Proyecto Fin de Carrera. ETSI Montes. Universidad Politécnica de Madrid. (2005).

(20) Arriaga, F., Esteban, M. y Argüelles, A., Bobadilla, I. e Íñiguez, G. Efecto de las gemas en la resistencia a flexion de piezas enterizas de madera. The effect of wanes on the bending strength of solid timber beams. Materiales de Construcción (mater construcc). Vol. 57, nº 288 (2007) pp: 61-76.

(21) UNE-EN 408. Estructuras de madera. Madera aserrada y madera laminada encolada para uso estructural. Determinación de algunas propiedades físicas y mecánicas (Timber structures. Sawn timber and glued laminated timber for structural use. Determination of some physical and mechanical properties).