| Frame tube structure is one of the common high-rise building structural systems.Its structure is a closed tube structure composed of close row outer columns and window skirt beams.This kind of building system can bear large loads in all directions,and its spatial stiffness and mechanical performance are better.It is widely used in super high-rise buildings.As the shear lag effect of frame tube structure is obvious,it can not be ignored.How to consider the influence of shear lag on the structure becomes the main problem in the design of frame tube structure.Temperature load is one of the common functions of the structure.At present,the research on shear lag effect of frame tube structure under temperature load is not enough.Based on the theoretical research and engineering practice data of shear lag effect of thin-walled box girder,according to the continuity principle,the frame tube composed of close columns and beams is transformed into a continuum structure,and the equivalent continuum mechanical model is taken as the object to carry out the mechanical analysis of shear lag effect.The specific work and main conclusions are as follows:1.According to the theory of equivalent continuity,the frame tube is equivalent to the solid web tube.On this basis,the axial force of the frame column with flange under the temperature load is analyzed.In this paper,a two parameter function is used to calculate the longitudinal displacement of the flange frame.The two parameters of the function can consider the difference of the maximum difference amplitude of the shear angle of the flange frame in different directions caused by the shear lag effect under the action of temperature.Based on the principle of minimum potential energy,the calculation formula of column internal force considering shear lag effect is derived.At the same time,the finite element software ANSYS is used to verify the reliability of the theory.The analysis shows that there is shear lag effect in the frame with two flanges.The longitudinal displacement of flange frame in different directions is similar,but the degree of shear lag is different.Under the action of temperature rising load,the deformation of the flange frame on both sides of the frame tube is upward convex,that is to say,the closer the flange frame on the sunny side is to the middle,the greater the elongation of the column is,the smaller the compression of the column is to the middle.Its deformation characteristics are different from that of frame tube under load.2.Based on the same simplified treatment method of the first point above,the equivalent ideal model is obtained to analyze the axial force of the flange frame column of the frame tube structure under the lateral load.In this paper,the longitudinal displacement of the flange frame is distributed as a quadratic function,and the web frame is distributed as a cubic function.Based on the principle of minimum potential energy,the calculation formula of the internal force of the column of the frame tube structure considering the shear lag effect is derived.Based on the calculation results of the finite element software ANSYS,the above theory is verified.The results show that the shear lag effect exists in the frame with flange on both sides of the tube and the bottom of the structure.The higher the floor,the more average the axial force of the columns.3.Based on the theoretical analysis method of shear lag of frame tube structure under temperature,the influence of corner column section area and window skirt beam section height on shear lag effect of frame tube structure under temperature load is analyzed.The results show that under the action of temperature load,with the increase of corner column section,the shear lag effect of frame tube is more obvious.With the increase of window skirt beam section height,the shear lag effect of frame tube decreases slightly.With the change of the length width ratio of frame tube plane,the shear lag effect of frame tube structure has no obvious change. |
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