Numerical Simulation Analysis Of Steel Reinforced Concrete Mega-Columns

Super-tall and mega-tall buildings are becoming the major part of the modern high-rise buildings. Mega-structures can not only meet the demand height of civil buildings, but also fulfill some special requirements, e.g. large space and large opening demands.So that the structural system is widely used in super-tall and mega-tall building. As one of main vertical and horizontal bearing component, the different behavior of mega-columns under various load conditions may affect the overall performance of the mega-structures. According to their different material composition, mega-columns can be divided into:①reinforced concrete mega-columns;②teel reinforce concrete mega-columns;③oncrete filled steel tubular mega-columns;④steel mega-columns. The object of this research is a SRC mega-column with a specific rectangle section layout. The performance of the column under various load conditions was analyzed by finite element numerical simulations. At end of the paper, some recommendations for design of SRC mega-columns are given based on the analysis results.The difference between the SRC mega-columns and the common SRC frame-columns such as:①the SRC mega-columns bear a bigger proportion of the overturning moment and storey shear compared to common columns in frame-tube structures;Din order to reduce the size and ensure ductility, the SRC mega-columns are usually manufactured with high-strength concrete and high-strength stirrups②he effective height of a SRC mega-column is determined by stability analysis, and is different in different projects④he layout of steel and the section form of stirrups in SRC mega-columns are more diverse⑤ecause of its huge size, a mega-column cannot be tested for size effect and distribution of cross strains in laboratory.The main research and contents of this paper are listed below:(1) Six variables, i.e.,axial compression ratio, concrete strength, steel ratio, shear span ratio, reinforcement ratio, and stirrup reinforcement ratio, were considered and analyzed for their contribution to the behavior of a SRC mega-column using two software (ABAQUS and OpenSEES). And Reasonable ranges for these parameters for design purposes were introduced and discussed along with some practical suggestion to use them. (2) The maximum horizontal capacity of SRC mega-columns was calculated using the method based on current code and section method, respectively. Comparison and analysis were performed on the differences between these results and output from the ABAQUS and OpenSEES analysis.(3) Some parameters were introduced to represent the influence of the size effect of concrete constitutive. It was pointed out that size effect have a big influence for strength, stiffness and ductility. And this should be paid attention at design of SRC mega-columns.(4) The influence of the steel layout on the behavior of the major and minor axis was discussed as well. Recommendations were made for proper steel layouts based on these discussions.(5) This paper also discussed conditions under which the plane cross-section assumption would be true for mega-columns, and proposed a revised method for distribution of cross strains when the assumption is false.Through these studies above show that mega-columns have different behavior, they need appropriate computation and measures at engineering design.