| The splicing of wooden components is a common form of connection in large-span wooden structures,which is essential in ensuring the structural realization of spatial spans and effective load transfer.As a new connection technology,self-tapping screw connection is gradually being applied in modern wooden structures.It is characterized by ease of construction,aesthetics,and reliable connection performance,making it one of the connection forms with broad application prospects in wooden structures.However,there is currently insufficient research on self-tapping screw connection nodes,and therefore,this study focuses on the glued laminated splicing nodes connected by selftapping screws used in actual engineering.Based on this,a new type of prestressed steel strap-self-tapping screw connection is proposed for glued laminated splicing nodes,and relevant research on the mechanical performance of these two types of nodes is carried out.A bending test was conducted on glued laminated splicing beam specimens connected by self-tapping screws under axial compression load,considering five selftapping screw layout forms.The study showed that the self-tapping screw layout form has a significant impact on the mechanical performance of the nodes,and the bending carrying capacity of the five sets of specimens reached 39.9%-65.5% of the intact beam.The vertically arranged self-tapping screws in the splicing area have an improving effect on the bending carrying capacity of the nodes,while the mixed angle arrangement of selftapping screws exhibits higher elastic bending stiffness.Adding horizontal oblique selftapping screws to reinforce the lower vertical gap can increase the bending carrying capacity and elastic bending stiffness of the nodes by 26.4% and 11.8%,respectively,but the ductility of the nodes is reduced.The finite element solid modeling analysis was carried out on the test node beams,and XFEM was introduced to simulate wood cracks.This method can accurately simulate the stress performance of the nodes,and the finite element analysis results are relatively accurate.Parameter analysis of the nodes was also conducted,considering the influence of axial force,lap joint length,and lap joint slope on the bending performance of the nodes.A new type of glulam spliced joint connected with prestressed steel strip and selftapping screws was proposed on the basis of pure tapping screw splicing glulam joint.The flexural properties of the jointed beam specimens under axial load were investigated under five self-tapping screw layout forms.The research results showed that compared with splicing nodes connected purely by self-tapping screws,the bending carrying capacity of the nodes can be improved by 8.4% to 51.3%.For self-tapping screws arranged at a single angle,the use of prestressed steel straps can improve the elastic stiffness of the nodes by 25.0% to 42.6%.The finite element solid model of the test node was established,and a simplified model with connector elements replacing the solid selftapping screws was verified for accuracy.Parameter analysis of the nodes was conducted using the simplified model,considering the influence of the number of steel straps and the pre-tension force of the steel straps on the bending performance of the nodes.Based on the assumption that the outermost self-tapping screw near the shoulder reaches the ultimate resistance capacity against pull-out and shear,a bending carrying capacity calculation model for self-tapping screw connection of glued laminated splicing nodes is proposed,and the theoretical results have an error within 10% of the experimental results.Based on this,a quasi-nonlinear fracture mechanics model based on an elastic foundation beam is introduced to consider the effect of the steel straps on the bending carrying capacity calculation model for prestressed nodes,and the calculation results are compared with the experimental results to verify the accuracy and applicability of the calculation model. |
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