Theoretical Analysis And Pseudo Dynamic Experimental Study On Tall Building Tubular Structure

In this thesis,the research work supported by national natural science foundation of China under Grant(50478092,50438020) has been carried out,which includes two aspects.With the computational method as the research object,the tube-in-tube structure of tall building is studied systematically regarding static analysis,dynamic analysis,overall stability and second-order analysis,based on continuous media mechanics,elastic theory of column shells and finite strip method of structural analysis.The corresponding computational method is developed.Additionally,a pseudo-dynamic experimental research of a 1/10 scale 15-storey steel-concrete hybrid structure has been done and nonlinear analysis of steel-concrete hybrid structure has also been completed.The main accomplishments are given in the following:(1) An improved finite strip method of three-dimensional static analysis of tall building tubular structure with arbitrary peripheral shape subjected to bending and torsion is developed,which extend the application area of traditional finite strip method.According to the theory of column shells,a column shell curvilinear strip is constructed in this method.The displacement functions are selected as follows:along the direction of strip width,the tangential displacement uses one-order Langrange interpolation, the normal displacement and section warping displacement use cubic Hermite interpolation,which can well take into account the shear-lag effect of tall building tubular structures.The orthogonal polynomials approximated well to deformation curves of bending-shear type are employed as the displacement basic function,which overcomes the disadvantage of the classic finite strip method that the stresses at the section of base are zero due to the employment of vibration function for a cantilever beam or trigonometric function as the displacement basic function.(2) An improved finite strip method is developed for analyzing dynamic properties of tall building tubular structure with arbitrary peripheral shape.The consistent mass matrixes of column shell curvilinear strip and floor slab are derived based on coupled vibration of bending and torsion in this method.The degree of freedom in dynamic analysis is greatly reduced by using the so-called static condensation technique without considering the vertical mass.The total number of degree of freedom is independent of the height of the tubular structure,but is dependent of the number of terms taken from the expansion of the displacement function about basic function.(3) An improved finite strip method of the calculations of overall stability and second-order analysis of tall building tubular structure with arbitrary peripheral shape is developed.Taking the potential energy of load action into account in the calculation of the total potential energy,the geometric stiffness matrix of the curvilinear shell strip is developed based on the principle of minimum potential energy.(4) The experimental results of the top displacement time history,the maximal floor displacement,inter-story displacement angle and bottom shear force-top displacement hysteretie loops of the hybrid structure under seven different earthquake actions have been obtained.The maximal top displacement arrives at one-sixtieth of the height of tall building steel-concrete hybrid structure under heavy earthquake,which shows the good limited deformation capacity of tall building steel-concrete hybrid structure(5) The test results indicate that the hybrid structure,with designed seismic resistance grade 7,remains in elastic stage and has no obvious failure characteristics under 7-degree basic intensity and 7-degree of rare earthquake.Cracks appear on the coupling beams,the floor slabs and the bottom layer of the core tube under the rare earthquake of magnitude of 8 degree and 9 degree,but the steel frame does not yield and the structure has good bearing capacity.At the peak acceleration of 1.0g and 1.6g of earthquake inputs,the cracks develop very quickly on the coupling beams, the horizontal cracks develop across the bottom surface of the core tube and some of the steel columns yield,while the steel-concrete hybrid structure still has some bearing capacity.Therefore,it can be concluded that with reasonable design,the steel-concrete hybrid structure will have good seismic behavior under earthquake actions,which can satisfy the requirements of"three-level performance objectives".(6) The sharing curves of horizontal force of hybrid structure under seven different earthquake actions have been obtained from test.The experimental results indicate that a large fraction of horizontal force is undertaken by the core tube when the structure is in the elastic range,and upon cracking of the core tube,which results in the internal force redistribution,the portion of sharing by steel frame increases.With the intensity of earthquake becomes larger and larger,the proportion of horizontal force undertaken by the steel frame increases constantly,and the steel frame acts as the second seismic resistant system.(7) The finite element program ABAQUS is applied to study the numerical simulation of failure process of steel-concrete hybrid structure under seven different earthquake actions.The analytical results of the top displacement time history,the sharing curves of horizontal force and the process of damage-failure have been obtained,which correlate well with the experimental results.The finite element analysis is verified by the test results,which indicates that the finite element analysis method can be used to simulate the failure process of some large and complex structures.