Experimental And Theoretical Study On Seismic Performance Of Frame With Special-shaped Multi-cell CFST Mega Columns

As critical vertical member, the multi-cell CFST columns with special shaped sectionhave been applied in some projects, and it keeps a rapid development. Based on the realsuper high building projects, the seismic behavior of multi-cell CFST columns with specialshaped section and multi-cell CFST columns with table tennis racket section have beenstudied. Further more, the seismic behavior of mega-frame with multi-cell CFST columnshas been researched.The experiment research and theoryanalysis has been carried out,andthe seismic design suggestions has been given. The main contributions of the research areas follows:1. A multi-cell CFST mega-column with special shaped sectionwith new seismicstructural measure has been proposed. Based on a practical super high building project, theexperimental research on seismic behavior of121/25scaled specimens of multi-cell CFSTmega-columns with hexagon and six-cell section has been carried out under horizontal lowcyclic loading in different direction. The load-bearing capacity, stiffness and itsdegeneration, ductility, hystereticproperties, energy dissipation capacity, and failurecharacteristics ofspecimens have been analyzed based ontheabove experiments.2. A multi-cell CFST column with table tennis racket section has been researched.Based on a practical super high building project, the experimental research on seismicbehavior of101/7scaled multi-cell CFST mega-column specimens was carried out underhorizontal low cyclic loading. The load-bearing capacity, stiffness and its degeneration,ductility, energy dissipation capacity, and failure characteristic of specimens have beenanalyzed based onthe above experiments.3. The yield mechanism of mega-frame with multi-cell CFST column with specialshaped sectionwas researched and revealed. Based on the practical super high buildingproject, the experimental research on seismic behavior of a1/25scaled mega-frame withmega-columns was carried out under horizontal low cyclic loading. The load-bearingcapacity, stiffness and its degeneration, ductility, energy dissipation capacity, and failurecharacteristic ofspecimen have been analyzed based on the above experiment.4. The seismic constructional measures of multi-cell CFST mega-columnsstrengthened at the bottom were suggested. And the seismic design suggestions ofmega-frame structure were proposed. Nonlinear finite element analysis on multi-cell CFSTmega-column with special shaped section was carried out, the damage and yield failureprocesswasrevealed as well. Calculated results coincide wellwiththe measured values.Main conclusions are asfollows:1. The multi-cell CFST mega-column with special shaped section has wellplastoelastic deformation capacity and good seismic behavior, the design requirements canbe fulfilled. 2. Compared with normal mega-columns, the load-bearing capacity, ductility, energydissipation capacity of the bottom strengthened mega-columns are greatly improved. Thespeed of their stiffness degeneration is slower, and the seismic behavior is significantlyimproved.3. The multi-cellCFST mega-column withtable tennis racket section has good seismicbehavior; and the design requirements can be fulfilled.4. The mega-frame with multi-cell CFST columns with special shaped section hasgood seismic behavior. It can be used in anti-seismatic design of super high buildings inseismic area.