Abstract
To investigate the bearing behavior of symmetrical full-scale different strength concrete filled double skin steel tube (CFDST) stub columns, 19 full-scale specimens were designed, considering the slenderness ratio (λ); the compression strength of core concrete and sandwich concrete (fcki, fcko), the thickness of the inner and outer steel tubes (ti, to); the diameter of inner and outer steel tubes (Di, Do); and the tensile strength of the inner and outer steel tubes (fyki, fyko) as the main parameters. Nonlinear constitutive models for concrete considering constraint effect were adopted, and a finite element (FE) model was established using ABAQUS software. By comparing the results between simulations and experiments, the rationality of the modeling method was verified. Based on the FE model, the parameter analysis for CFDST columns were conducted, and the force mechanism, stress distribution, and deformation process were analyzed. The results showed that the axial compression bearing capacity (Nsu) increased significantly with an increase in fcki, to, Do, and fcko, while Nsu decreased gradually with an increase in λ. Finally, according to the calculated results of the specimens, the calculation formula for Nsu of full-scale composite columns was statistically regressed using 1stOpt software and showed a good agreement with the FE.
Highlights
With the rapid revitalization of old industrial bases in northeastern China, the reconstruction of adding stories around the existing buildings has become a hot topic in the field of civil engineering [1,2]
The axial compression bearing capacity of concrete filled double skin steel tube (CFDST) columns will greatly be improved, and the ductility and seismic performance will be significantly better than those of ordinary concrete filled single steel tube (CFST) columns [10]
Ekmekyapar [25] experimentally studied the axial compression behavior of 34 CFDST columns, and the results showed that the failure model of the CFDST members was, essentially, similar to that of the CFST members
Summary
With the rapid revitalization of old industrial bases in northeastern China, the reconstruction of adding stories around the existing buildings has become a hot topic in the field of civil engineering [1,2]. Numerical simulation analysis of the mec2hoafn20ical behavior of full-scale CFDST stub columns subjected to an axial load was carried out using ABAQUS [27], and the rationality of modeling method was verified. The axial compression bearing capacity, ductility, and stiffness were significantly improved due to the existence of the double skin steel tubes. It is insufficient to conduct the research on the mechanism behavior of CFDST members considering the size effect, and the applicability of the calculation formula for the bearing capacity based on the reduced-scale models to the full-scale specimens has not been verified. Numerical simulation analysis of the mechanical behavior of full-scale CFDST stub columns subjected to an axial load was carried out using ABAQUS [27], and the rationality of modeling method was verified. The bearing capacity formula for the full-scale CFDST composite stub columns could be statistically regressed using 1stOpt software, which could be used in engineering practices
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