Research On Influencing Parameters Of Bending Behavior Of Glulam Beams Connected With Steel Splints And Bolts

As a kind of green environmental protection building material with sustainable development,glulam has the advantages of good material property,flexible construction,high ratio of strength to quality,anti-corrosion and moisture-proof,heat preservation and insulation,short construction period,harmonious and beautiful appearance,etc.With the development of modern wood structure engineering towards large-span high-rise buildings,the demand for large-size glulam beams is increasing.In order to realize the span of glulam beams,the form of steel plywood bolt connection can be used.In order to further explore the influence of parameter changes on the bending performance of steel plywood bolted glulam beams,this paper conducts static test on 13 groups of steel plywood bolted glulam beams,calculates their ultimate bearing capacity through theoretical analysis,and studies 9 influencing parameters by using 25 groups of finite element models established by the finite element software ANSYS.The main research contents include the following aspects:(1)The bending performance test of 13 groups of steel plywood-bolted glued-wood beams was carried out.The load-deflection curve,ultimate bearing capacity and bending stiffness of each group of specimens were compared and analyzed.The results show that the effect of bolt parallel spacing on the flexural performance of steel plywood bolted glulam beams is significant,while the effect of bolt parallel,staggered arrangement and whether the two beams are from the same glulam is small;with the increase of bolt parallel spacing,the ultimate bearing capacity and the initial flexural rigidity of the specimens gradually increase;steel plywood bolted glulam The initial rigidity of the beam is larger than that of the pure glulam beam,but the later rigidity is smaller than that of the pure glulam beam.(2)The finite element software ANSYS was used to perform numerical simulation analysis on the test specimen,and the constitutive relationship obtained from the material property test was used to calculate the corresponding load-deflection curve,ultimate bearing capacity,stress distribution cloud diagram,etc.,and the finite element results and test results were obtained.By comparison,the results show that the finite element results are in good agreement with the experimental results,which verifies the accuracy and rationality of the finite element model of steel plywood-bolted bonded wood beams.(3)The ultimate load capacity of steel plywood-bolted glued-wood beams was calculated by the upper and lower limit bearing capacity method,and the calculation results were compared with the test results and finite element simulation results.The results show that the upper and lower limit method of ultimate bearing capacity can accurately predict the range of ultimate bearing capacity of steel plate bolted joint,the average value of upper and lower limit of ultimate bearing capacity is close to the ultimate bearing capacity of steel plate bolted glulam beam bending test,and the calculation results are in good agreement with the finite element simulation results.(4)By using the validated finite element modeling method,25 groups of ANSYS finite element models were established to study the influence of 9 parameters,including bolt end distance,edge distance,spacing,row distance,diameter,quantity,thickness and shape of steel splints and thickness of glulam,on the bending performance of steel plywood bolt glulam beam.The results show that:with the increase of bolt spacing,the influence of changing bolt parameters on the ultimate bearing capacity is gradually weakened;the increase of bolt end spacing and diameter can enhance the ultimate bearing capacity of steel plate bolt joint;the increase of bolt edge spacing or the decrease of bolt spacing and number will reduce the ultimate bearing capacity of specimens;the thickness of steel plate has a significant impact on the ultimate bearing capacity and failure mode,when the steel plate When the thickness is taken as 1～1.5d,the mechanical properties of the steel plate bolt joint are good and the material consumption is small;the U-shaped steel plate can provide enough bending capacity and reduce the consumption of bolts and steel.When the thickness of.glulam is less than or equal to 80mm,increasing the thickness of glulam can significantly improve the ultimate bearing capacity of the test piece.