ESTIMATION OF STRENGTH OF GLULAM BEAMS DEPENDING ON DEFECTS OF LAYERS

Summary Timber, as structural material, has various defects, especially knots. They influence the strength of timber members. The influence of knots is lower for glulam members when comparing with solid wood. The article is the theoretical and experimental investigation of influence of knots on the strength of glulam beams. Theoretical investigation deals with probability of coinciding of knots in the same cross-section of member. The factors of influence of knots on glulam beam strength are the results of theoretical investigations. The short-term tests on 12 model beams with measurements 2140×120×152(h) mm were carried out in a testing machine. Results of these tests are in line with the conclusions of theoretical investigations and show the higher strength of glulam beams when comparing with solid members of the same quality. The long-term tests were carried out on model beams when temperature and moisture were cyclically changed. Wetting cycle—14 days long, drying cycle—7 days. Two series, 12 model be...