Research On The Bending Performance Of Double-section Bolted Assembled Nodes Of Rectangular Steel Tube Single-layer Lattice Shel

The lattice shell structure has significant characteristics such as excellent spanning ability,rich architectural design,and superior economic indicators,making it one of the most widely used forms of spatial structure.As one of the forms of reticulated shell structures,single-layer reticulated shell structures have been widely used worldwide due to their small number of nodes and members,lightweight and beautiful architectural effects,and good permeability.The types of lattice shell members mainly include round steel pipes,rectangular steel pipes,and H-shaped steel pipes.In single-layer reticulated shell structures,the members mainly bear the effects of axial force and bending moment.Therefore,considering the bending resistance,torsional resistance,and stability comprehensively,rectangular tubes are more suitable for single-layer reticulated shell structures.The node system is an important component of single-layer reticulated shell structures.The nodes of single-layer reticulated shell structures are mainly divided into two types: welded nodes and bolted connection nodes.The bearing capacity of welded joints is relatively high,but welding needs to be carried out on the construction site,which is difficult and difficult to ensure construction quality;The components required for bolted connection nodes can be prefabricated in the factory,and only bolted connections are required at the construction site.Bolted connection nodes are easy to install,fast in construction speed,and easy to ensure construction quality.The bolted connection nodes that can be applied to rectangular tube single-layer lattice shells can fully leverage the installation and performance advantages of bolted connection nodes and rectangular tube members.Therefore,this article conducts research on the double bolt assembled joints suitable for rectangular steel tube single-layer lattice shells,on the basis of SLO nodes,a new type of SLO node using a split node body is innovatively proposed,we conducted research on the mechanical properties of two different types of nodes in pure bending state.The main research work of this article is as follows:(1)A new type of SLO node using a split node body is proposed based on SLO nodes.The weight of the split type node body was compared with that of the integrated type node body.When the aspect ratio of the rectangular tube section is greater than or equal to 2:1,the weight of the split type node body is significantly reduced compared to the integrated type node body;(2)Based on the component method in EC3,a simplified mechanical model suitable for SLO nodes and new types of SLO nodes in pure bending state was proposed,and the calculation formulas for the initial rotational stiffness and yield moment of these nodes were derived;(3)For two different forms of nodes,7 sets of specimens with typical parameters were designed and experimental studies were conducted on the nodes under pure bending.The mechanical properties of each group of specimens,such as bending moment angle curve,failure mode,and bending bearing capacity,were obtained,and the experimental results were compared with the theoretical calculation results to verify the correctness of the theoretical calculation;(4)Finite element simulation was conducted on the test specimens.The correctness of finite element simulation was verified by comparing the mechanical properties of specimens in finite element simulation and experiments,such as failure modes,node bending moment rotation curves,and bending bearing capacity.The stress development process and failure mechanism of specimens with different parameters were analyzed and compared,and the influence of different node body forms and node parameters on the mechanical properties of these types of joints was obtained;(5)Based on the above research,the recommended failure mode for this type of node is provided,and the determination method and recommended values of key parameters in the node are clarified,providing a theoretical basis for the design of single-layer reticulated shell structures using this type of node.