# Seismic Behaviour of CFST Space Intersecting Nodes in an Oblique Mesh
## 1 Introduction  
With the acceleration of urbanization, modern high-rise buildings are rapidly developing with a new appearance [1, 2, 3]. As the building height increases, the lateral stiffness of the structure becomes a vital issue in the design. Under the conditions of ensuring structural safety and economy, selecting an economical, efficient, and effective structural system that can control the lateral displacement of high-rise structures became a new trend. The oblique mesh structure is a form of a structure composed of intersecting steel pipes and nodes. It has the advantages of a simple structure, high stiffness, and good seismic performance and was widely used in high-rise buildings [4, 5, 6, 7, 8, 9]. The intersecting node is formed bythe intersection of four diagonal steel pipes in space. The existence of intersecting nodes will cause stress concentration at the node, thereby affecting the stability and safety of the structure. Therefore, the design of intersecting nodes in oblique mesh structures is essential. Therefore, studying the problem of intersecting nodes has important theoretical and practical significance in civil engineering. In recent years, scholars from various countries made specific achievements in the research of oblique mesh structures. [PERSON] et al. [10] conducted research on the mechanical properties of intersecting nodes of diagrid structures composed of steel fibre-reinforced recycled concrete columns (OOSFRCIN). The study showed that OOSFRCIN has good mechanical properties and can be applied to engineering practice. [PERSON] et al. [11] conducted experimental and numerical studies on the post-fire performance of steel tube T-joints filled with concrete. The results showed that due to the support provided by the core concrete to the steel tube, the failure mode of the node was plasticization of the steel tube rather than local buckling of the steel tube wall. [PERSON] et al. [12] conducted finite element analysis on the KK-intersecting nodes and analyzed the difference between the nodes with and without stiffening ribs, providing a reference for practical engineering. [PERSON] et al. [13] used ABAQUS to analyze the influence of different parameters on the mechanical behaviour of steel tubes intersecting nodes, considering cumulative damage. [PERSON] et al. [14] proposed a theoretical formula for the bearing capacity of spatially connected diagrid systems. [PERSON] et al. [15] conducted finite element analysis on the nodes formed by the connection of steel tube concrete columns and RC beams, mainly studying the axial compression performance of the nodes. [PERSON] et al. [16] found that the intersecting connection can fully develop plastic deformation during the loading process and analyzed the influence of different parameters on its mechanical properties, finally giving design suggestions. [PERSON] et al. [17] used the stiffness equivalence principle to solve the critical problems in the preliminary design of high-rise diagrid structures: optimization of the intersecting angle and evaluation of the shear lag effect. [PERSON] et al. [18; 19] summarized the influence of anti-lateral stiffness-related factors on the plastic development process, stress distribution, and stiffness degradation of diagrid structures. [PERSON] and his team [20; 21; 22; 23; 24; 25] proposed a new type of node for diagrid structures and conducted research on it using experimental, numerical, and theoretical analysis methods. In summary, existing research on oblique mesh intersecting nodes (OMIN) mainly focused on the mechanical properties of plane intersecting nodes under monotonic loads. At the same time, there is less research on the mechanical properties of nodes under reciprocating loads [26; 27; 28]. Moreover, plane intersecting nodes cannot consider the contribution of the node's out-of-plane angle and floor beam to the node's out-of-plane stiffness in actual structures.