Vpliv značilnosti slovenskega smrekovega konstrukcijskega žaganega lesa na njegove mehanske lastnosti in prevedba sortirnih razredov v trdnostne

Šega, Bogdan (author)

Predstavljamo povezave med vizualno ugotovljenimi značilnostmi konstrukcijskega žaganega lesa izdelanega iz slovenske smrekovine (Picea abies(L.) Karst.) in njegovimi mehanskimi lastnostmi. Posušen žagani les smo vizualno razvrstili v sortirne razrede na podlagi SIST DIN 4074-1. Rezultate vizualnega razvrščanja smo primerjali z dobljenimi odločilnimi lastnostmi (upogibna trdnost, modul elastičnosti in gostota). Upogibna trdnost je bila najbolj odvisna od širine branike (r=-0,52), deleža grč (r=-0,50), zvitosti (r=-0,23) in oddaljenosti od stržena (r=0,12). Sortirni razred je bil najpogosteje dodeljen na podlagi ocene grč, sledijo zvitost, prisotnost stržena in širina branike. 10 % preskušancev je bilo razvrščenih v razred S13,58 % v razred S10, 15 % v razred S7, 17 % pa je bilo izločenih. Ugotovljene karakteristične vrednosti sortirnih razredov S13, S10 in S7 so bile višje od zahtev SIST EN 338 za trdnostne razrede C30, C24 oz. C18. Rezultati raziskave predstavljajo osnovo, na podlagi katere bo omogočeno prevajanje sortirnih razredov v trdnostne.

• Language: Slovenian
• Keywords: smreka, konstrukcijski les, vizualno razvrščanje, trdnostni razredi
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Publisher: Zveza društev inženirjev in tehnikov gozdarstva in lesarstva Slovenije
• Year: 2010
• Number of pages: Str. 483-489
• Numbering: Letn. 62, št. 11/12
• PID: 20.500.12556/RUL-56452
• UDC: 630*832.181
• ISSN on article: 0024-1067
• COBISS.SI-ID: 1874313
• Publication date in RUL: 10.07.2015

Record is a part of a journal

• Title: Les
• Shortened title: Les
• Publisher: Zveza društev inženirjev in tehnikov gozdarstva in lesarstva Slovenije, Zveza društev inženirjev in tehnikov gozdarstva in lesarstva Slovenije, Biotehniška fakulteta, Oddelek za lesarstvo, Založba Univerze, Biotehniška fakulteta, Oddelek za lesarstvo, Založba Univerze
• ISSN: 0024-1067
• COBISS.SI-ID: 13940224

Secondary language

• Language: English
• Title: Influence of characteristics of stuctural sawn timber made from Slovenian spruce on its mechanical properties and assignment of visual grades to strength classes

Abstract

We present correlations between visually determined characteristics of structural sawn timber produced from Slovenian spruce (Picea abies (L.) Karst.) and its mechanical properties. Dried sawn timber was visually graded into sorting classes according to SIST DIN 4074-1. Results of visual grading were compared with grade determining properties (bending strength, modulus of elasticity and density). The main strength reducing charasteristics were the rate of growth (r =- 0.52), knot ratio (r =- 0.50), twist (r =- 0.23) and distance from the pith (r = 0.12). The most decisive factors to judge lower grade were however knots, followed by twist, the presence of pith and rate of growth. 10% of the specimens were graded to class S13, 58% to class S10, 15% to class S7, 17% of the specimens were rejected. The determined characteristicvalues of sorting classes S13, S10 and S7 were higher than the requirements of SIST EN 338 for the strength classes C30, C24 and C18 respectively. The results of this study represent a basis on which visual grades can be assigned to a strength classes.

• Keywords: spruce, structural timber, visual stress grading, characteristic values, strength classes