Đang chuẩn bị liên kết để tải về tài liệu:
Báo cáo lâm nghiệp: "properties of Norway spruce timber. Comparison between fast- and slow-grown stands and influence of radial position of sawn timber"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Bending properties of Norway spruce timber. Comparison between fast- and slow-grown stands and influence of radial position of sawn timber. | Ann. Sci. For. 55 1998 349-358 Inra Elsevier Paris 349 Original article Bending properties of Norway spruce timber. Comparison between fast- and slow-grown stands and influence of radial position of sawn timber I. Robert Kliger Mikael Perstorper Germund Johansson Chalmers University of Technology Department of Structural Engineering Division of Steel and Timber Structures SE-412 96 Goteborg Sweden Received 5 November 1996 accepted 25 November 1997 Abstract - The primary objective of this work was to study one aspect of improving timber quality. The aim of this paper is to supplement previously published results in Wood Science and Technology. Bending strength and stiffness of Norway spruce Piceci cihies from three stands in southern Sweden two fast-grown and one slow-grown were measured. Radial variations were studied using six studs 45 mm X 70 mm X 2 900 mm per log cut along a diameter with a total of 500 studs. The bending strength of studs from the slow-grown stand was 57 higher and the modulus of elasticity 54 higher than that of the fast-grown stands. The bending strength of studs from mature wood near the bark was 47 higher and modulus of elasticity 30 higher than that of the core studs. The improvement in mechanical properties from pith to bark was far more significant for the studs from the slow-grown stand than from the fast-grown ones. lnra Elsevier Paris. Norway spruce strength stiffness mechanical performance Resume - Propriétés de flexion de 1 épicéa commun. Comparaison entre sites à croissance rapide et lente et influence de la position radiale des sciages. L objectif premier de ce travail est Tétude de paramètres importants contrôlant la qualité des sciages. Cette étude complete des résultats publiés précédemment. La resistance et la rigidité en flexion de 1 épicéa commun Picea abies provenant de trois sites du sud de la Suède deux à croissance rapide et un à croissance lente ont été mesurées. Pour 1 étude des variations radiales six debits 45 X 70 X