| The spatial reticulated shell structure is more and more applied in engineering practice,and the structural shape of the reticulated shell is becoming more and more diverse,and the node types of the reticulated shell are also constantly updated and iterated,and the more beautiful,simple and low-cost nodes are pursued.cost,ease of construction,etc.The triodetic joint is a prefabricated joint with the above advantages.It was widely used in the early wooden structures in China.In the field of steel structures,the research on the triodetic joints abroad is relatively thorough.There are almost no applications of reticulated shells with triodetic joints,and there is a lack of corresponding normative guidance.Therefore,the research on reticulated shells with triodetic joints has certain value for practical engineering applications.In view of the above background,this paper mainly carried out the following research:Firstly,this paper calculates and analyzes the overall model of the triodetic joint:the joint model is established by using CAD software,and then the model is imported into the ABAQUS analysis software,considering the influence of the rod on the overall model and the influence of geometric nonlinearity,the ideal elastic-plastic constitutive model is adopted,and the C3D8element type is selected,and the joint rod end is fixedly supported,and the center of the hub body is coupled to apply a vertical load for analysis and calculation.The ratio of the moment-rotation angle obtained from the bending moment-rotation angle curve is used as the node stiffness,and compared with the node stiffness of the simplified model,the initial stiffness formula of the node obtained by the simplified model through parameter regression is corrected.The effect of different camber angles on the joint stiffness is studied,and the conclusion that the joint stiffness increases with the increase of the camber angle is obtained,and the camber angle is also used as a parameter and substituted into the stiffness formula for correction,and the stiffness calculation formula of the whole model of the triodetic joint considering the camber angle is obtained.Comparing the stiffness values of such triodetic joints,it is found that they all belong to the category of semi-rigid joints.And the stiffness comparison analysis with the bolted ball joints shows that the performance of this kind of triodetic joints is better than that of the bolted ball joints.Then,with the help of ANSYS analysis software and the self-built command flow program,a K8 single-layer spherical reticulated shell is established,and the obtained semi-rigid joint stiffness data of triodetic joints with different camber angles were substituted into the stability research of the triodetic joint reticulated shell,and compared with the rigid joint reticulated shell.The combin39 element is used to simulate the out-of-plane and in-plane stiffness of the triodetic joints.First,the buckling analysis is carried out,the first eigenvalue and the first ten buckling modes are extracted,and the influence of parameters such as joint stiffness,span,and rise-span ratio on the first eigenvalue is obtained.Then consider the initial defects,conduct nonlinear overall stability analysis,draw the load-displacement whole process curve,calculate the load coefficient and extract the instability mode,and determine the influence of parameters such as node stiffness,span,and rise-span ratio on the overall stability of the reticulated shell sexual influence.The stability of the reticulated shell with bolted ball joints commonly used in engineering is compared and analyzed.Through the analysis of a large number of calculation examples,the stability performance of the K8 spherical reticulated shell with semi-rigid joints such as triodetic joints has been grasped comprehensively.Finally,the dynamic performance analysis of the K8 type single-layer spherical reticulated shell is carried out through the finite element analysis software ANSYS,and the dynamic response of the K8 type reticulated shell with semi-rigid joints such as triodetic joints and the difference from the rigidly connected reticulated shell are systematically studied.Firstly,the natural vibration characteristics are analyzed,including the natural vibration frequency distribution and mode shape change law,and the influence laws of joint stiffness,span,rise-span ratio and other parameters on the natural vibration characteristics of reticulated shells are obtained.Then,the dynamic time-history analysis was carried out,and the seismic wave commonly used in the second-class site—EI Centro seismic wave was selected.The time interval of the seismic wave was 0.005s,the total recording duration was 10s,and the peak acceleration was 0.35m/s~2,and the seismic wave was subjected to amplitude modulation processing.Enter acceleration in a ratio of 1:0.85:0.5.The displacement time-history curve and acceleration time-history curve of the joints are plotted,and the variation law of the seismic response of the reticulated shell with the joint stiffness,span,rise-span ratio and other reticulated shell parameters is obtained.The dynamic performance of the reticulated shell with bolted ball joints is compared and analyzed.The dynamic performance of the K8 spherical reticulated shell with semi-rigid joints such as triodetic joints has been mastered comprehensively. |
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