Study On Basic Mechanical Properties Of High-rise Hexagonal Grid Tube Structures

Nowadays,the population of various countries are gathering in cities on a large scale.The pressure brought by limited space has had a profound impact on urban construction.The traditional building forms with simple structures and single functions in the past can no longer meet the needs of people and aesthetic needs.The high-rise hexagonal grid tube structure is a supplement to the grid layout of the facade of the diagrid tube structure.By virtue of the greater lateral rigidity of the structure as a whole,there is more space between the components.Good spatial collaboration capabilities and superior daylight performance of the facade have been applied to landmark buildings in economically developed cities or regions.But at present,it is only limited to individual engineering cases,and the research on its mechanical properties is not mature yet,the theoretical system that has guiding significance for engineering practice has not been established.Therefore,drawing upon existing technical practices and theoretical publications,this article will conduct research on the mechanical properties,seismic performance and structural ductility of high-rise hexagonal grid tube structures.The main research work and results are as follows:1.By simulating the force situation of the 12-story diagrid tube and hexagonal grid tube structure the distribution characteristics and transmission modes of internal forces under vertical load and horizontal load are compared and analyzed.The results show that the internal forces of the two structures are transmitted through the axial force of the inclined column under the vertical load and the horizontal load.In comparison,the force transmission path of the hexagonal grid tube structure is clearer,and the space between the components is clearer.The ability to work together is stronger.However,because of the top layer cannot be rigidly connected by diagonal columns and horizontal beams to form a hexagonal grid unit,that is,only ring beams can be set,resulting in a sudden change in stiffness on the top layer.Therefore,in the actual engineering structure design,the premature yielding of the top ring beam should be avoided to affect the structure.2.The seismic analysis of high-rise hexagonal grid tube structures has been established in combination with the practical engineering implementation of the influence of angle inclined column under seismic action of the transverse performance of the hexagonal grid tube proportional structure and the internal and external frame stiffness of the tube has been studied.Based on the analysis of the force of the hexagonal grid element,a method based on the assumption of rigid floor to calculate the ratio of the bending stiffness to the shear stiffness of the high-rise hexagonal grid tube structure to derive the optimal angle of the inclined column is proposed.The image determines that the optimal angle of the model is 55°～60°.Finally,the internal force distribution characteristics between the inner and outer cylinders of the high-rise hexagonal grid tube structure with different inclined column angles are analyzed.The results show that under the seismic load,the outer tube of the frame bears more than half of the bending moment and most of the shear force,which has an impact on the structure.Seismic performance of the main part.3.Two different modes of the combined modes of CQC and SRSS in the modal decomposition response spectrum method were used for modal analysis of the model.The lateral displacement curves obtained are compared with the dynamic time-history analysis results.There are errors but it does not affect the actual analysis results.The parameters of the first six-order modal natural vibration period,period ratio,and damping ratio of the high-rise hexagonal grid tube structure with different inclined column angles are compared,and the inclined column section of the hexagonal grid tube structure is derived based on the stiffness design principle.Dimension calculation formula,the calculated change trend of the interlayer displacement angle of the structure is basically close to the change trend of the interlayer displacement angle analyzed is basically close to that of the finite element software simulation analysis,and the value is slightly bigger than other values.Therefore,it is believed that the simplified calculation method of the preliminary design of the section has been verified.And it is more conservative and safe in actual use.And on this basis,the relation curve between the bending shear displacement ratio at the top of the structure,meanwhile both the height-width ratio of the structure and the method to confirm the structure’s reasonable height-width ratio are all obtained.4.The static elasto-plastic analysis of the high-rise hexagonal grid tube structure is carried out using the lateral force distribution method of the multi-mode combination.By combining the base shear force-top displacement curve and the yield path method,the structure with different angles of the inclined column is found The difference in the development law of plastic hinges is compared with the research on the plastic development and yield path of the oblique grid tube structure in the existing literature.It explores the feasibility of improving the overall ductility of the structure by changing the length a’ of the plastic platform under axial plastic hinge compression,as well as the bearing capacity c’ of the structure after buckling are developed,and the method of adjusting the diameter-thickness ratio of the structural frame of the concrete-filled steel tube inclined column members is also proposed.