| Because of high space utilization and high height,the frame-core-tube structure occupies a large proportion in modern super high-rise buildings.However,due to complex shape and various types of elements,these structures which under seismic action have more complicated dynamic characteristics.Therefore it’s necessary to use the numerical means to study the mechanism of the strong earthquake disaster,and to describe the structure’s damage evolution in order to carry out the seismic performance design of the super high-rise structure effectively.As the main anti-lateral force component of the frame-core-tube structure,the numerical model of the shear wall is very important,the layered shell model which based on the theory of composite mechanics can simulate the complex force characteristics of shear wall,but it’s not very suitable for the shear wall in the super high-rise structure.Consequently it’s necessary to improve the layered shell model so that it can be better applied to the simulation of the shear wall,further describe the damage model of the shear wall and conduct analysis of structure.Based on the above concerns,the following work has been done in this paper.(1)Based on the analysis and evaluation of the geometric large deformation shell NLDKGQ and the concrete material based on the modified compression field theory,a modified shell model is established by improving the shell element and the concrete material respectively.Due to its deficiency for the out-of-plane performance of shear walls,the NLDKGQ is improved in the model with replacement of the thin-thick plate element TMQ which is based on the generalized conformation theory,the improved shell which called ShellGNL with a capability to simulate efficiently the out-of-plane performance of shear walls in super high-rise buildings.The efficiency of the improved model is further improved with the utilization of reduced integration scheme.For concrete material constitutive,in order to improve the stability of the numerical calculation and to simulate the shear wall more accurately,the compression constitutive and the shear modulus of cracked concrete is modified,at the same time,Mander model is used to consider the restraint effect of stirrups on the concrete in the dark column.The improved nonlinear layered shell model is established based on the C ++ language programming platform and is integrated into the dynamic time history analysis program DUT.(2)The accuracy of the improved layered shell model is tested by slabs,shear walls and frame-shear wall structures.According to the simulation of elastic slab and RC slab,it is found that the NLDKGQ element is not suitable for the large thickness-to-length ratios,ShellGNL has enough calculation precision and convergence speed for both thin and thick plate.For the simulation of shear wall,different kinds of RC shear walls under monotonic loading and low cyclic loading are tested which proves the model’s applicability and high accuracy.Then the modified layered shell model is applied to the calculation of SRC walls and frame-shear wall structures,and its performance is demonstrated by comparison with SAP2000 and experimental results.The adoption of shell elements with out-of-plane performance is recommended when the structure possesses obvious shear effect and large number of shear walls with relative large thickness-to-length ratios.(3)In order to study the damage evolution rule of reinforced concrete shear wall,a damage model is proposed based on the nonlinear combination of displacement and hysteretic energy term.This model has the ability to consider dynamic changes of the two parameters’ contribution in the damage process of RC shear walls under seismic actions,at the same time,the potential boundary convergence problems are solved by the irreversible deformation serving as the displacement term.Multiple sets of test data of shear wall specimens are utilized to determine the combination coefficients,together with finite element program.The proposed model is then applied in the damage computation of shear walls under cyclic loadings and incremental dynamic analyses,verifying its accuracy and reasonability.The damage evolution of shear walls are analyzed with this model considering height-width ratio,boundary stirrup ratio and normalized compressive stress.It is disclosed by the results that a large height-width ratio would lead to early yielding and relatively-favorable ductility of shear wall;a large boundary stirrup ratio,within a reasonable range,could decelerate the damage development;and a large normalized compressive stress contributes to decreased ductility and accelerated damage evolution of shear walls.(4)Nonlinear dynamic time history analysis on frame-core-tube super high-rise building is carried out by DUT program which is integrated by the improved layered shell model.Firstly,the influence of different layered shell models on the whole and local response of the height of 258 m and 660 m frame-core-tube super high-rise building is studied.It’s found that material model has great effect on the two aspects,and shell element has little influence on overall structural responses but in-negligible impact on the shear walls.Through the study of structural damage evolution and the sensitivity of the key components to the structural damage,it’s found that the strengthening of the frame column can not only reduce the overall response of the structure,but also can effectively slow down the structural damage development.Therefore,within the permissible range it is recommended to enhance the safety reliability of the structure by strengthening the outer frame columns. |
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