| Modern building structures tend to be the concept of large-span,high-rise and green environment protection.Timber structures have attracted much attention because of its natural advantages.Among them,the single-layer reticulated shell structures with light weight,high strength,reasonable force transmission and simple assembly are one of the widely used structural forms in the timber space structure system.Numerous examples of timber construction applications abroad show that steel connectors,as an important connection and force transmission mechanism for single-layer reticulated shell joints,mostly have large dead weight and exposure of the steel,which not only waste material but also affect the appearance and weaken the overall wooden atmosphere of the structure.Therefore,the research group designed a new type of prefabricated timber reticulated shell connection.Aiming at the split failure phenomenon of the rods in the axial compression test,the "improvement first" measures were proposed,and the axial compression and bending tests were carried out respectively.Although the splitting caused by torsion was avoided,the deviation and design problems in the assembly process still exist.In this page,a "re-improvement" scheme is proposed to solve the problem.The numerical simulation method is adopted to compare the mechanical performance of the improved joint and the re-improved special-shaped dowel joint,which is a further supplement and deepen to the experimental research and has certain engineering significance.The research work and conclusions of this paper mainly include the following aspects:(1)Establishing fine model of first improved test joint,set the same boundary conditions and loading method as the test,perform finite element analysis on it under the separate action of axial compression and vertical load.The stress cloud diagram,loaddisplacement curve,bending moment-angle curve,etc.obtained by finite element simulation are extracted.Compared with the test results,it is found that they are in good agreement,which verifies the accuracy of the finite element software modeling and analysis method.(2)Referring to the test results of the first improved joint,considering the influence of installation deviation and in combination with the《Wood Structure Design Standard》(GB50005-2017),a re-improved scheme of the joint structure form was proposed,and the positions of the timbe holes and steel of the special shaped connectors were adjusted.Using the established modeling method,the finite element model of the re-improved joint was established for simulation analysis,and the bearing capacity of the re-improved joint was checked.The results show that the bearing capacity of the re-improved joint is better and slightly higher than first-improved joint,indicating that the re-improved design scheme is reasonable.(3)Considering the joints in practical engineering applications are often combined with effect of axial compression,bending moment and shear,the more focus are on the mechanical performance of the joints under the combined work of axial compression and vertical load.The numerical simulation results of first improved joint and re-improved joint show that the force performance of the joint under axial compression is significantly better than that without axial compression;At the same time,as the axial compression increases,the ultimate flexural bearing capacity of the joint is also improve;Axial compression will increase the initial bending stiffness of the joint.(4)Study on the effect of the change of the dowel size,bolt strength,steel plate thickness and other parameters for the bearing capacity of the joints.The results show that: as the dowel diameter and bolt strength increase,the bending capacity of the joint improves;the thickness of the steel plate increases or decrease has little effect on bearing capacity. |
