Investigation On The Mechanical Behavior Of Double-Ring Joint Of Assembly Single-Layer Spatial Reticulated Structure

Assembly single-layer spatial reticulated structure which is characterized by reasonable stress distribution,nodes performance guarantee,efficient construction and friendly working environment,is becoming the hotspot and the trend of construction field.While,as the most widely used assembly joint,bolted spherical node is under concern that it will cause security problems as a result of the looseness of bolts and manufacturing imperfection.Besides,there are few development researches about new assembly joints,which cannot satisfy the increasing demand of single-layer spatial reticulated structure for construction modelling,economic cost,and engineering construction and so on.For that matter,a new joint,double-ring joint,for assembly single-layer spatial reticulated structure is proposed,and the main content of this thesis includes:(1)Research and development of double-ring jointBased on the application and working features of free-curved single-layer reticulated structures,Double-ring Joint,which is not only lightweight but also easy to assemble,was developed.And the basic machining accuracy of the joint can meet the demand of construction,which satisfy the demand of spatial reticulated structure for positioning the spatial angle of joints.Additionally,both the primary and the secondary members are able to be connected with the joint in the spatial reticulated structure,especially in the single-layer triangular spatial reticulated structures which are composed of primary and secondary members,thus a large number of steel can be saved.(2)Static performance test of double-ring jointThe influence of the section dimension of members,the diameter of bolts,the thickness-diameter ratio of the ring and the thickness of plates is investigated by static tests under the bending-shear and the compression-bending loads.The whole M-? curve and failure modes of the joints were obtained based on the deferent parameters.The influence of the deferent parameters on the mechanical behavior of the joint was concluded.(3)Numerical simulation on double-ring jointNumerical analysis models ware established herein by the means of commercial FEA software ANSYS to evaluate the mechanical behavior and the failure modes of the joints under the bending-shear and the compression-bending loads.The good agreement between the experiment results and the numerical results confirmed that the FEA models were able to simulate the mechanical behavior of double-ring joints with reasonable accuracy.(4)Theoretical analysis of double-ring jointThe failure modes of the joints were deeply analyzed on the basis of tests and numerical analysis,by which the parameters determining certain failure mode were defined.There were two primary failure modes.One was the failure of bolts and the other was the failure of rings.The two-stage design method was proposed according to the internal force of the assembly single-layer spatial reticulated structure and the construction features of double-ring joints as well as the failure modes.The evaluation of the bearing capacity of the joints with deferent failure modes were discussed.Finally,the mechanical behavior of the joints was compared to that of rigid joints in order to evaluate the mechanical behavior of double-ring joints,which are helpful for the engineering design.