RESULTS OF EXPERIMENTAL STUDIES OF THE GLUED WOOD OF STRUCTURAL DIMENSIONS UNDER A RIGID TEST MODE
Keywords:
glued wood, compression along the fibers, diagrams of deformation, stress, deformations, rigid mode of testsAbstract
The methodology of experimental studies of glued hardwood and softwood by axial compression along the fibers on modern testing equipment is presented. On the basis of the conducted experiment, real deformation diagrams of glued wood with ascending and descending branches were constructed.
The true strength and deformation parameters have been established. The following strength indicators were obtained in the 1st section: birch wood σc1= 9.0 MPa; alder σc1= 7.2 MPa; ash σc1= 9.1 MPa; larch σc1= 9.6 MPa; pines σc1= 8.1 MPa; spruce σc1= 7.4 MPa. Deformation characteristics had the following values: for glued birch wood uс1=0.00071; alder uс1=0.00067; ash uс1=0.00062; larch uс1=0.00073; pine uс1=0.00064; spruce uс1=0.00057.
For prisms made of glued wood, the following values were recorded at the upper maximum point of the diagram: birch strength fc,0,d =55.0 MPa, critical strains uc,0,d,exp=0.00493; alder strength fc,0,d=50.9 MPa, critical strains uc,0,d,exp=0.00450; ash strength fc,0,d =66.6 MPa, uc,0,d,exp=0.00597; larch fc,0,d =68.8 MPa, critical strains uc,0,d,exp =0.00672; pine strength fc,0,d =51.2 MPa, uc,0,d,exp =0.00521; spruce fc,0,d =53.7 MPa, critical strains uc,0,d,exp =0.00453.
The limit deformations at the end of the III section had the following indicators: for glued birch wood uc,u=0.00802; alder - uc,u=0.00671; ash - uc,u=0.01036; larches - uc,u=0.00848; pine - uc,u=0.00711; spruce - uc,u=0.00704.
In the fourth section, only the final deformations under stresses σс,fin=0,1fc,0,d are given, since the destruction of the samples followed, and then their complete unloading. The relative residual deformations of glued wood had the following indicators: birch prisms reached the mark uc,fin=0.3349; alder - uc,fin=0.2796; ash - uc,fin=0.4793; larch uc,fin=0.4589; pine uc,fin=0.3526; spruce uc,fin=0.3042.
It was found that in all areas of the diagram, an increase in strength and insignificant fluctuations in one or another direction of deformability were observed in comparison with samples of solid wood with a standard moisture content of 12% aged 60 years.
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