Study On Bearing Performance Of Glulam Bolted Joints For Japanese Larch

The characteristics of Larix kaempferi are fast growing and high yield, straight trunk,strong disease resistance, good material and low cost, et al, which is one of the most importantspecies. So far, the majority of plantation japanese larch are mature. It is very important tomake full use of this part of resources.Larix kaempferi were taken as the research material, theendpresure of different finger length were achieved. Also, the tension strength, compressionstrength and bending strength of finger joint lumber were studied. the mechanical properties ofdowel bearing properties and bolted joints of glulam were discussed thoroughly. Theconnection properties and main influence factor of japanese larch glued laminated timber wereclarified.Main results are summarized as follows:(1)The mechanical properties of13mm finger length vertical gearing milling fingerjointed lumber are better, the endpressing value is3.813MPa, the tension strength, compressionstrengh and bending shtrength of which are35.827MPa,44.133MPa and46.587MParespectively, variation coefficient are all below20%.(2)The influence factor order ranked by importance degree of dowel bearing is as follows:lamination degree>bolt diameter> strength direction. Test method has no influence on dowelbearing properties.When the bolt diameter is12mm, the5%-offset strength, max-bearingstrength tested by full hole method are10.516MPa,15.583MPa.(3)The influence factor order ranked by importance degree of yield strength of bolted jointis as follows: bolt diameter>bolt degree>lamination degree. Maximum load of glued laminatedtimber is effected by lamination degree significantly, but the bolt diamter and bolt degree haveno influence.When bolt diamter are12mm, the yield strength, proportional load and maxmiumload are5.676MPa、5.797kN and15.574kN respectively. (4)Foschi equation is highly adaptable to predict the load-displacement curves of japaneselarch glulam wood-wood bolt double shear joint. R-square are all above0.8, which indicatesthe fitting effect is good.(5)The test strength of japanese larch glulam bolt joint is higher than design value, whichindicated that japanese larch can meet the requirements of timber structure bolted joints.