The Influence Of The Reinforced Layersposition On The Spatial Stress Performance Of Tube-in-tube Structures

With the continuous improvement of China’s national strength and the development of building height towards a higher field,the lateral displacement of the structure under horizontal load becomes more and more important.In the design of high-rise structures,one of the main tasks of structural engineers is to find the best solution to control the lateral deformation of the structure under wind load or seismic load.When the lateral displacement of the structure is too large,the usual method is to increase the stiffness of the anti-lateral force structure,such as shear wall,cylinder,etc.,to control the deformation.But this kind of method,not only makes the structure of the cost increase,also due to the large vertical component of section and adverse impact on the use of building function,but also for tall building often adopt the structure of the form,such as the frame-core tube structure,tube in tube structure,etc.,shall be borne by the inner barrel overturning moment only often cannot meet the requirements of the lateral limit.Therefore,in recent years,many researchers have proposed the idea of setting rigid boom to enhance the lateral stiffness of high-rise buildings,that is,to enhance the stiffness of horizontal structure in the appropriate parts of high-rise buildings,so that the inner cylinder and the outer frame column can work together as a whole to control their lateral deformation.Increasing the lateral stiffness of the structure by setting the reinforcement layer can reduce the cost and have a beneficial impact on the structural stress.If the setting of the reinforcement layer is combined with the equipment layer,the space can be fully utilized.In this paper,according to the requirements of the relevant specifications,a 245-metre-high tube in the tube structure-changsha st.Regis hotel has carried out a variety of strengthening layer Settings analysis.(1)the finite element method,the paper discusses the strengthening of 12 kinds of model layer set on the properties of tube in tube structure space stress effects,respectively from different positions of the strengthening layer,such as no strengthening layer,located at the top of the structure and structure in central location,such as stiffness,different number,such as setting one,two,three,four,the perspective of strengthening layer,to study the strengthening layer effect on the properties of tube in tube structure space stress;(2)based on the two criteria of reducing structural lateral displacement and improving structural stress,this paper conducts research and analysis in combination with practical projects.(3)the influence of various strengthening layer setting schemes under two different horizontal loads on the natural vibration period,peak lateral displacement,internal and external cylinder shear force,bending moment distribution was studied.(4)by means of deformation coordination,the equilibrium equation is established,and the formula for calculating the internal force of the external cylindrical column connected with the horizontal rigid arm and the expression for the relationship between the bending stiffness of the horizontal reinforcement and the axial stiffness of the column are obtained by using the method of structural mechanics.The results show that:1)the reasonable setting of the reinforcement layer can effectively improve the shear lag effect of the structure,so that the internal force of the structure is redistributed in a favorable direction;2)for reducing the lateral displacement of the structure,the effect of strengthening layer in the tube-in-tube structure is not as obvious as that of the frame-core tube structure,and the effect of setting external frame ring beam on the basis of setting hogizontal rigid arm in the tube-in-tube structure is also not as significant as that of the frame-core tube structure;3)the stiffness of the reinforcement layer should not be too large,otherwise it is easy for the structure to generate a weak layer,which is not conducive to the seismic resistance of the structure;4)when the reinforcement layer is uniformly set along the height of the structure,the optimal position of the reinforcement layer can be neglected.Based on the research,some Suggestions are put forward for the strengthening layer of the tube-in-tube structure in practical engineering.