The Simplified Mechanical Model And Nonlinear Seismic ResponseAnalysis Of Mega-frame Column

With the development of economy and the progress of the society, the conventionalstructures are difficult to meet the requirements, so the high-rise and super high-rise buildingsare springing up. Mega structure system composes of mega column and mega beam, it canmeet the needs of high-rise buildings better because of its definit load condition,flexiblelayout and lateral stiffness. As a result, it has been used widely in super high-rise buildings inrecent years. As the important force component in mega structure system, mega frame columnhas more members, so how its force performance is obtains widely attention. At present, mostof mega frame column researches are focusing on the static aspect, while the researches indynamic performance of the mega frame column are less studied. In this paper, the seismicperformance of the mega frame column is studied based on its nonlinear analysis.The major research content of this article:1. The simplified mechanical model and nonlinear seismic response analysis ofmega-frame columnThe continuous Timoshenko beam model is adopted to simulate the mega frame column,the equivalent continuous model of mega frame column is established by this way, then theequivalent bending stiffness and equivalent shear stiffness can be obtained, and based on theenergy variational method the displacement under the action of static and the nature vibrationof the mega frame column is analyzed, the analytical solutions of displacement, lateralvibration frequency and mode can be given. Finally, the result obtained by the energyvariational method is compared with that obtained by the analysis of the finite element, andthe correctness of the equivalent model and the accuracy of the energy variational method canbe verified.2. Nonlinear analysis of mega frame columnOn the basis of the different slenderness ratios and axial compression ratios,12kinds ofmega frame columns are designed. Using the method of modified stiffness and modifiedplastic bending moment, based on the analytical method the lateral force-displacement curveof the mega frame column is obtained which considering the second-order effect, thegeometric nonlinearity and the material nonlinearity are considered in the same time, And thefinite element software ABAQUS is adopted to simulate the mega frame column. The curveobtained by the analytical method of modified stiffness and modified plastic bending momentis compared with that obtained by finite element, the results are in good agreement, which provides an effective theoretical method for the analysis of the mega frame columnconsidering the second-order effect.3. Seismic response analysis of mega frame column6kinds of mega frame columns are choosed and the elastic-plastic time history analysisis conducted under the action of three different seismic waves, and the second-order effect onthe elasto-plastic time history curve of the mega frame column is considered. The analysisresults show that the second-order effect on the elastic-plastic displacement time history curveof the mega frame column under the action of seismic wave has a significant impact whichcan not be ignored, and it may give a design recommendation to practical engineering.