Yield Strength Of Steel Tube Research Articles

Axial compressive behavior of reinforced hollow circular high strength concrete filled steel tubular short columns

This study aims to investigate the mechanical behavior of reinforced hollow circular high-strength concrete-filled steel tubular (RHCFST) short columns under axial compression. The axial compression test of 6 RHCFST short columns was carried out, and the bearing capacity, ductility and failure modes of the columns were analyzed. The results revealed that the failure modes of RHCFST short columns primarily included mixed failure, shear failure, and crushing failure. Comparatively, the failure modes of specimens with ordinary reinforcement exhibited a shift towards mixed failure, significant improvement in ductility, and a decrease in the increase trend of ultimate bearing capacity with the growth of steel tube thickness. Based on the test results, finite element models were developed using ABAQUS software for parameter analysis. The results demonstrated a positive correlation between the short column’s bearing capacity and parameters such as steel strength, sandwich concrete strength, steel tube thickness, and ordinary reinforcement diameter. Additionally, the initial stiffness of the short column increased with the increase of steel tube thickness. Considering the mechanical properties and engineering applicability of the member, the recommended design of steel tube yield strength, sandwich concrete strength, steel tube thickness and ordinary reinforcement diameter were given. Furthermore, the axial bearing capacity calculation formulae for RHCFST short columns were proposed. The calculated values were found to closely match both experimental and simulated values, with errors falling within 10 %. Consequently, the formulae can offer a reliable prediction of the member’s axial bearing capacity.

Behavior of Circular Hollow Steel-Reinforced Concrete Columns under Axial Compression

The circular hollow steel-reinforced concrete (HSRC) column consists of an inner circular hollow steel tube and outer circular hollow reinforced concrete (RC). This design provides several advantages, including being lightweight, having a wide sectional profile, and having a high flexural stiffness. This paper aims to investigate the behavior of the circular HSRC columns under axial compression through testing and finite element (FE) modeling. An FE model was established to simulate the circular HSRC columns under axial compression, which was validated against the test data. Additionally, the load distribution and the interface stress between the outer hollow RC and inner steel tube were analyzed. Subsequently, a systematic parametric analysis was conducted on the diameter (d) and thickness (t) of the steel tube; slenderness ratio (λ); strength of concrete (fcu); yield strength of steel tube (fsy), longitudinal rebar (fly), and stirrup (fgy); as well as the stirrup spacing (s). The critical influencing factors of the circular HSRC columns under axial compression were identified. fcu, λ, d, fly, and fsy dramatically influence the bearing capacity, and the stiffness is notably affected by λ and fcu. Finally, three simplified design methods were summarized and evaluated for calculating the bearing capacity of the circular HSRC columns under axial compression.

Nonlinear finite element and machine learning modeling of tubed reinforced concrete columns under eccentric axial compression loading

There is still insufficient data on the behavior of tubed-reinforced concrete columns (TRCCs) under the eccentric compression. Thus, this research work comprehensively examines the eccentric compression behavior of TRCCs using nonlinear finite element modeling and machine learning (ML). To do this, numerical simulation and parametric analysis based on existing investigations were conducted. In addition to the existing 22 specimens with limited test variables, additional 188 specimens were developed to cover a wide range of parameters, including the load eccentricity, transverse reinforcement spacing, columns’ slenderness ratio, yield strength of steel, and outer steel tube diameter. Additionally, six ML models were created to estimate the ultimate load results. The results indicated that increasing the outer steel tube yield strength and diameter, and reducing the load eccentricity, slenderness ratio, and spacing of the transverse reinforcement enhanced the load-carrying capacity of the columns. The Gaussian process regression model demonstrated superior performance metrics in comparison to other ML models, with the highest R2 values (0.998613 in training and 0.99823 in testing stages) and lowest root mean square error values (0.007213 in training and 0.008471 in testing stages). To save money, time, and resources compared to laboratory testing, an online-based prediction program is finally presented to predict the columns’ ultimate load.

Axial Compression Behavior of Elliptical Concrete-Filled Steel Tube Composite Short Columns with Encased Steel Considering Spherical-Cap Gap

This study explored the axial compression behavior of elliptical concrete-filled steel tubes with encased steel considering spherical-cap gap (GSECFST) composite short columns. We designed 25 composite column specimens by varying the steel tube yield strength (fty), steel skeleton yield strength (fsy), concrete cubic compression strength (fcu), steel tube thickness (t), steel skeleton sectional area (As), the long and short half-axis ratio (a/b), the gap ratio (Xsg), and the slenderness ratio (λ). Based on the nonlinear constitutive models of the materials and the nonlinear contact effect among materials, the ABAQUS 6.20 finite element software established the refined finite element models of these composite short columns. Also, the rationality of the finite element modeling with a spherical-cap gap was verified by comparing it with the existing experimental results. The influence regularity of various parameters on the load (N)-displacement (Δ) curves, bearing capacity, initial stiffness, and ductility of the composite short columns was obtained. In addition, the failure modes, N-Δ process, sectional strain distribution, and gap feature index of the constraint partition model for GSECFST axial compression short columns were revealed. The results showed a weakened interaction between the elliptical steel tube and concrete. Also, the axial compression bearing capacity, initial stiffness, and core concrete ductility were reduced because of the spherical-cap gap. As fty, fsy, fc, and Asy increased, the axial bearing capacity, initial stiffness, and ductility of GSECFST composite short columns improved significantly but decreased with increasing of a/b, Xsg, and λ. When the gap ratio of the spherical crown was less than 4%, the outer steel tubes in the mid-span area of the GSECFST composite short columns buckled in the direction of the elliptical short axis under axial compression, and the concrete expanded outward and crushed. The failures were similar to those of the specimens without the spherical-cap gap. Based on the sectional constraint partition model, we propose the calculation formula of axial compression bearing capacity for GSECFST composite short columns. Consequently, this study is a reference for the elastic-plastic analysis of frame systems with similar composite columns.

Axial compression behavior of square section concrete-filled steel tubes reinforced with internal latticed steel angles

The axial compression behavior of square CFSTs (concrete-filled steel tubes) reinforced with internal latticed steel angles was investigated in this study, and the test results including load-displacement and load-strain behavior, failure modes, and ultimate load were obtained. The experimental results demonstrated that the steel angles exerted an additional confining effect on the enclosed concrete, and altered the stress distributions of the adjacent concrete. The corresponding finite element model was established subsequent to the experiment, and the analysis and discussion of the axial compression mechanisms was conducted. The parametric analysis was performed to evaluate the influence of main parameters on the load-displacement behavior, and the analysis results revealed that the concrete made the highest contribution to the ultimate load. Additionally, the formulas for calculating the ultimate load were proposed according to the superposition method, and the calculation results demonstrated that the design formula derives from the unified theory of CFSTs exhibit enhanced accuracy and reduced deviation. Finally, a reliability analysis was conducted to evaluate the feasibility of the proposed design formula, and the analysis results indicated the calculated reliability index decreases with an increase in the steel ratio, and for specimens with a higher steel ratio, a lower yield strength of steel tube leads to a lower reliability index.

Load–Displacement Behaviour and a Parametric Study of Hybrid Rubberised Concrete Double-Skin Tubular Columns

Rubberised concrete has emerged as a material of interest to the research community with the mission of creating sustainable structural members and decreasing the burden of waste tyre rubber. The potential benefits of replacing natural aggregates with rubber particles to obtain greater energy absorption and ductility are proven in the literature. To negate the reduction in capacity due to the addition of rubber particles, single- and double-skin confinements were proposed and successfully tested by researchers. Hybrid rubberised double-skin tubular columns (RuDSTCs) were recently trialled and tested by the authors. Each of these hybrid RuDSTCs had a filament-wound carbon fibre-reinforced polymer (CFRP) outer tube and an inner steel tube with rubberised concrete as the sandwich material between the two tubes. To explore the axial behaviour of such a column, this paper develops a finite element modelling strategy and carries out a comprehensive parametric study of the hybrid RuDSTC with 0%, 15%, and 30% combined aggregates replaced with rubber particles. This methodology is validated by experimental results, and a good agreement is found. Hybrid RuDSTC models are developed in four groups with different material and geometric parameters, in addition to those corresponding to the experimentally tested column, to explore the effects of the thickness ratio, hollow ratio, steel tube yield strength, and CFRP tube diameter with a special focus on the transition of the characteristic bilinear stress–strain curve of the hybrid RuDSTCs. The results show the smooth transition of the stress–strain curve with increasing rubber content after the yielding of steel, which indicates better ductility of the rubberised columns. The novel hybrid RuDSTCs can provide a promising sustainable solution with greater capacity compared with their unconfined counterparts. Better strain and enhanced ductility of the hybrid RuDSTCs compared with non-rubberized hybrid DSTCs enable their use in seismic-prone regions and mining infrastructure.

Application of ensemble model in capacity prediction of the CCFST columns under axial and eccentric loading

Understanding the load-carrying capacity of circular concrete-filled steel tube (CCFST) columns is crucial for designing CCFST structures. However, traditional empirical formulas often yield inconsistent results for the same scenario, causing confusion for decision makers. Additionally, simple regression analysis is unable to accurately predict the complex mapping relationship between input and output variables. To address these limitations, this paper proposes an ensemble model that incorporates multiple input features, such as component geometry and material properties, to predict CCFST load capacity. The model is trained and tested on two datasets comprising 1305 tests on CCFST columns under concentric loading and 499 tests under eccentric loading. The results demonstrate that the proposed ensemble model outperforms conventional support vector regression and random forest models in terms of the determination coefficient (R2) and error metrics (MAE, RMSE, and MAPE). Moreover, a feature analysis based on the Shapley additive interpretation (SHAP) technique indicates that column diameter is the most critical factor affecting compressive strength. Other important factors include tube thickness, yield strength of steel tube, and concrete compressive strength, all of which have a positive effect on load capacity. Conversely, an increase in column length or eccentricity leads to a decrease in load capacity. These findings can provide useful insights and guidance for the design of CCFST columns.

Seismic Performance of Concrete Column Connection with Square-Upper-Circular-Lower Steel Tube for Antique Buildings

The antique building combines traditional design with contemporary technology, making it an important structural style. Columns, as a crucial structural component, directly affect how well the building functions as a whole. This paper proposes a new connection form with the upper square concrete-filled steel tube-lower circular concrete-filled steel tube (USCFST-LCCFST). This study investigates the seismic performance of the proposed connection form of the columns. First, the finite element software ABAQUS-2021 is used to simulate and analyze the connection forms of the upper square concrete-filled steel tube and lower circular reinforced concrete (USCFST-LCRC) and the upper square steel reinforced concrete and lower circular reinforced concrete (USSRC-LCRC) above the antique building, respectively, which confirms the rationality of the modeling method explored in this paper. Then, geometric modeling of the USCFST-LCCFST connection is performed using ABAQUS. Simulation results demonstrate the superior seismic performance of the proposed connection form. In addition, the influence law of steel tube yield strength and the ratio of upper and lower column linear stiffness on its seismic performance are analyzed and determined through the variational parameter analysis of the USCFST-LCCFST connection form. The steel tube yield strength of USCFST-LCCFST column connection components is recommended to be 355–420 MPa and the ratio of upper and lower column linear stiffness should be no less than 0.063. In order to ensure the good seismic performance of the connection, the steel tube yield strength and the ratio of upper and lower column stiffness should be efficiently controlled in the design of antique buildings’ USCFST-LCCFST column connection components.

Behaviour and Design of Innovative Connections of Prefabricated CFST Columns under Tension

This paper investigates the tensile behaviour of prefabricated concrete-filled steel tube (PCFST) columns with bolted connections. Innovative bolted column-column (BCC) connections are developed using standard structural bolts to simplify the construction process for the connection of two PCFST columns, especially for the corner, edge, and interior columns. The behaviour of BCC connections in PCFST columns under tension has been investigated, adopting the finite element (FE) modelling approach. Parametric studies are carried out to understand the influence of bolt arrangements (TB = 4, 6, 7, 8), base plate thickness (tbp = 8, 10, 14, and 18 mm), bolt diameters (db = 16, 18, 20, 24 mm), vertical stiffeners (ths = 4, 6, 8, 10 mm), horizontal stiffeners (ths = 10, 12, 13, 15 mm), and yield strength of steel tube (fy,t = 380, 450, and 550 MPa) on the behaviour of PCFST columns with developed BCC connections. The results show that the PCFST columns with the developed BCC connections can attain sufficient tensile strength and satisfy the tensile strength requirements recommended in AS5100 and the robustness requirements in AS1170. The outcome of this paper will be useful to practising structural engineers to design prefabricated CFST columns with BCC connections under tension.

Parametric Study on the Behavior of Steel Tube Columns with Infilled Concrete—An Analytical Study

Concrete-filled steel tube (CFST) columns are used in tall buildings and bridges, and they provide more rigidity and higher bearing capacity, but buckling affects their behavior. There is an exceptional need to study the behavior of these columns under various conditions. The numerical method is beneficial in supplementing the experimental works and is used to explore the effects of various parameters because of the limitations in cost, apparatus, and time of the experimental program. The various parameters, such as the different slenderness ratios, i.e., column-height-to-cross-section-dimension (H/D), different steel-tube-thickness-to-column-dimension (D/t), and different compressive strength of concrete to yield strength of steel tube ratio (fc/fy) under concentric axial loading are considered in this current study. Firstly, a finite element model used the “ANSYS” software program and was constructed to validate the results of the experimental works. The extensive numerical models were carried out to extensively widen the study in this field. The numerical work was conducted on sixty-four specimens. Moreover, the analytical calculations from the different international codes/standards were compared with the numerical results to test their reliability in predicting the ultimate carrying loads. The study provided results that show the improvement effect of CFST columns with the high compressive strength of infilled concrete, while no remarkable enhancement effect with the high yield strength of steel tube was observed. Increasing the columns’ diameter is more effective in enhancing the load capacity (about three times more) than increasing the tube thickness (about 1.3 times). Ring stiffeners for long CFST columns (H/D > 12) do not lead to any enhancement of the column behavior due to yielding occurring firstly at the location of the rings. ECP205-2007 is the most conservative design code in predicting the load capacity of CFST columns, while the AIJ design code is good at predicting the ultimate load failure compared to the other codes/standards. Eurocode 4 provides underestimation values of the load-carrying capacity of CFST columns.

Behaviour of axially compressed CTHST stub columns with inner spiral stirrup

In this paper, a new type of concrete-filled thin-walled high-strength steel tube (CTHST) columns with inner spiral stirrup is proposed. This new type of columns provides dual constraints to the concrete core by both outer steel tube and inner spiral stirrup. To explore the structural performance of this new type of composite members, a pilot study into stub columns under axial compression was carried out. A total of 16 axially compressed specimens, 8 in circular section and 8 in square section, were tested with the various volumetric stirrup ratio (ρ, from 0 to 2.4 %) and yield strength of steel tube (fyt, 571.2 MPa and 648.9 MPa). The experimental results show that, the inner spiral stirrup has little impact on the overall failure pattern of each component of the specimens, but controls the horizontal angle of the failure plane, and the capacity, composite elastic modulus and ductility coefficient of the specimens increase as ρ and fyt increase. In addition, a nonlinear finite element (FE) model was established, and the representative mechanism of axially compressed CTHST stub columns with inner spiral stirrup under different ρ was further studied by the verified FE model. Finally, a calculation method to predict the capacity of the new composite members was developed, which considers the strength improvement of stirrup confined concrete. This method provided an accurate prediction of the capacity of axially compressed CTHST stub columns with inner spiral stirrup.

Bearing behavior of high-performance concrete-filled high-strength steel tube composite columns subjected to eccentrical load

In order to study the bearing capacity of high-performance concrete-filled high-strength steel tube (HCHST) composite stub columns subjected to eccentrical load, 22 HCHST composite stub columns, 4 concrete-filled steel tube (CFST) composite stub columns and 8 high-performance concrete-filled steel tube (HCST) composite stub columns were designed with the cubic compressive strength of concrete (fcu), the yield strength of steel tube (fy), the thickness of tube wall (t), the eccentricity (e) and slenderness ratio (λ) as the main parameters. Considering the nonlinear constitutive model of concrete and simplified constitutive model of steel, the finite element (FE) model of HCHST composite stub columns was established by ABAQUS software. By comparison with the existing test results, the rationality of the constitutive model and boundary conditions was verified. The variation of ultimate bearing capacity and the typical failure modes of HCHST composite stub columns under different parameters was analyzed. The results show that the specimens exhibit obvious bulge outward at the end of the steel tube and shear failure at the end of concrete. High-performance concrete (HPC) can significantly improve the ultimate eccentrical compression bearing capacity of composite columns, and high-strength steel tubes have better restraint effect on HPC. With the increasing of t, the ultimate eccentrical compression bearing capacity and the load-holding capacity of HCHST columns increases gradually, while the ultimate eccentrical compression bearing capacity decreases gradually with the increasing of λ and e. By introducing the reduction coefficient of eccentricity (φ1) and the reduction coefficient of slenderness ratio (φ2), the calculation formula of the eccentric bearing capacity of HCHST columns is proposed by statistical regression, which can lay a foundation for the application of HCHST columns in practical engineering.

Finite Element Modelling of Ultimate Strength of CFST Column and Its Comparison with Design Codes

Concrete-filled steel tube (CFST) members have high strength, stiffness, and ductility properties, which makes them favorable in structural applications. This study purposes to create a finite element analysis-based model for designing the peak strength of axially loaded CFSTcircular columns. To this aim, 314 test specimens presented in the previous experimental studies were investigated. In the study, the wall thickness and yield strength of steel tube, compressive strength of concrete, and column diameter and length were designated as the design parameters. In this regard, the design model created using the finite element analysis proposed in this study was evaluated comparatively with existing ones given in the existing design codes and standards such as ACI, AS, AISC, AIJ, Eurocode 4, DL/T, and CISC. Besides, the estimation performance of all design models was examined statistically as well.

Hysteretic Behavior of H‐Shaped Honeycombed Steel Web Composite Columns with Rectangular Concrete‐Filled Steel Tube Flanges

This study aims to investigate the hysteretic behavior of H‐shaped honeycombed steel web composite columns with rectangular concrete‐filled steel tube flanges (STHCCs). Taking the shear span ratio (λs), axial compression ratio (n), steel ratio of section (α), aspect ratio of section (D/B), yield strength of steel tube (fyfk), and compressive strength of concrete (fck) as the main parameters, we designed 22 full‐scale STHCCs. By comparing the load‐displacement curves between test and simulation, the rationality of finite element modeling method was verified. The quasi‐static analysis of 22 specimens was carried out, and the influence regularity of different variables on the hysteretic behavior, skeleton curves, ductility, energy dissipation, resistance degradation, and stiffness degradation of STHCCs was obtained. The results show that the hysteresis curves of all the specimens show full shuttle shape and strong energy dissipation capacity. λs, α, and fyfk have great influence on the bearing capacity of skeleton curves. With the increase of α and fyfk, the initial stiffness of the specimens gradually increases. The stiffness degradation rate of the specimens gradually slows down, and the energy dissipation coefficient gradually decreases by increasing λs, α, and fyfk, but energy dissipation capacity is still at a high level. The resistance degradation of specimens increases gradually by increasing λs, α, fyfk, and D/B. The ductility of specimens gradually increases by increasing n, α, and fck. The maximum bulging deformation and maximum stress of specimens appear at the column foot. The trilinear skeleton curve model and restoring force model of STHCCs are established by statistical regression.

Fire resistance of thin-walled steel tube confined reinforced concrete middle-length columns: Test and numerical simulation

Steel tube confined reinforced concrete (STCRC) column is a new type of composite compressive member. In recent years, the structural performance of the STCRC columns has been widely studied to promote its application, and this paper presents experimental and numerical studies on the fire-resistance behaviour of the middle-length members. Parameters, including thickness of steel tube, loading mode (axial or eccentric), and load ratio, were considered in the tests. Moreover, the furnace temperature, column temperature, axial displacement, lateral displacement, and applied load were recorded during the tests, and the failure pattern was obtained after the tests. The finite element model (FEM) was developed by ABAQUS and validated against the test results. Through parametric analyses, the effects from eccentric ratio, load ratio, cross-section diameter, material strength, the thickness of steel tube, and reinforcement ratio on the fire resistance of the middle-length STCRC columns were further studied. It was found that increasing the section diameter, concrete strength, yield strength of reinforcement, and reinforcement ratio would enhance the fire resistance of the columns. However, increasing eccentricity, yield strength of steel tube, thickness of steel tube, and load ratio would reduce the fire resistance of the columns.

Experimental and analytical investigation on fire resistance of circular tubed steel reinforced concrete medium-long columns

This paper presents experimental and numerical studies on the fire-resistance behavior of the circular tubed steel reinforced concrete (CTSRC) medium-long column. Parameters, including steel thickness, loading mode (axial or eccentric), and load ratio, were considered in the tests. Moreover, the furnace temperature, column temperature, axial displacement, lateral displacement, and applied load were recorded during the tests, and the failure pattern was obtained after the tests. The test results showed that when the load ratio increased from 0.4 to 0.6, it would lead to an approximately 37%–54% decrease in failure time. Moreover, when the specimen was loaded with an eccentricity ratio (e/D) of 12.5%, the failure time would be 17%–39% less than that of the axially loaded specimen. The finite element model (FEM) was developed by ABAQUS and validated against the test results. Furthermore, through parametric analyses, more parameters, such as cross-sectional diameter, material strength, and length to diameter ratio, were studied. It was found that the fire resistance increased with the cross-sectional diameter, concrete strength, yield strength of the H-steel, and the steel ratio of the H-steel, whereas it decreased with the eccentricity ratio, yield strength of steel tube, steel ratio of the steel tube, and load ratio. Based on the experimental and numerical results, a simplified design method for predicting the fire resistance of CTSRC columns under ISO-834 standard fire was proposed. The design method was proved to have a good agreement with numerical analyses and test results within a specific application range.

Axial compressive behavior on steel tube-retrofitted circular RC short columns with grout under preload

Steel tubes are widely used in strengthening reinforced concrete (RC) columns. However, in engineering construction, the effect of preload on the original RC column on the performance of strengthened RC column has not mostly considered. Therefore this paper tests five circular short columns under axial compression—three steel tube-strengthened RC columns with preload, one strengthened RC column with no preload, and one normal RC-to study compressive performance of steel tube-retrofitted circular RC short columns under various preload levels. Moreover, the verified finite element numerical model is established using ABAQUS software to stimulate the behavior of the retrofitted columns. The extended parametric studies is conducted based on the thickness of steel tube, yield strength of steel tube, and strength of grout under preload, in addition to preload level itself. A practical design method is proposed and compared with four existing design codes to predict the axial compressive ultimate strength of the retrofitted column under preload.

Behaviour and design of prefabricated CFST stub columns with PCC connections under compression

This paper investigates the compressive behaviour of prefabricated concrete-filled steel tube (CFST) columns with prefabricated column–column (PCC) connections. The innovative PCC connections are designed using conventional structural bolts instead of expensive blind bolts to connect two prefabricated CFST columns, simplifying the construction process and rendering the construction cost-effective. The compressive behaviour of prefabricated CFST columns with or without PCC connections has been investigated numerically. Parametric studies have been conducted to investigate the effect of different parameters of PCC connections, including connection configurations, horizontal and vertical stiffeners of connections, diameter of the coupling bolt, steel tube thickness, yield strength of steel tube, and compression strength of concrete, on the compressive behaviour of CFST columns with PCC connections. The prefabricated CSFT columns with the developed PCC connections are able to achieve similar compressive strengths that are achieved by the CFST columns without connections. Therefore, the developed PCC connections can be used to construct prefabricated CFST columns for the prefabricated steel–concrete composite structures.

Size effect prediction on axial compression strength of circular CFST columns

Based on size effect law of plain concrete, a size-dependent analytical model for axially loaded CFST column was developed by considering the influence of confinement on size effect. The proposed model can make a similar forecasting precision for CFST specimens in different size ranges, and it was efficient to predict the size effect of axial compression strength, therefore it was used here to conduct the parametric analysis on size effect of CFST column. The analysis results indicated that the size effect of axial compression strength was connected with the confinement level apart from the specimen size. As the steel ratio of the specimen or yield strength of steel tube increased, size effect of axial compression strength tended to become less obvious. Conversely, the size effect was more obvious as the concrete strength increased. Based on parametric analysis, a formula was developed to predict the size effect of axial compression strength for CFST specimens by considering the specimen size and the influence of confinement factor.

Axial compression performance of thin-walled T-shaped concrete filled steel tubular columns under constant high temperature: Experimental and numerical study

This study investigates the effects of temperature and stiffener on the axial compression performance of thin-walled T-shaped concrete filled steel tubular (CFST) stub columns. Eight CFST columns with and without stiffener were fabricated and exposed to different elevated temperatures, then tested for axial compressive performance. The complete load-displacement curve of the specimens under axial compression, the failure pattern after test and the failure characteristics of concrete core are also discussed. The finite element analysis is then developed to establish the calculation model of temperature field and axial pressure field of thin-walled T-shaped concrete filled steel tubular stub columns with stiffeners at constant high temperature. The FE model presents a highly agreement with experimental data in term of load-displacement behavior, which enable to further investigate stress distribution and failure mechanism of the columns. In addition, parametric study is conducted showing that temperature, thickness of steel tube, yield strength of steel tube and compressive strength of concrete are the key factors in contributing to axial compressive performance of the CFST stub columns. Finally, to provide reference for practical application of engineering, a simplified calculation formula for ultimate bearing capacity and axial compression stiffness of CFST stub columns were obtained via the regression analysis based on results from the experimental and numerical analysis. The result shows that the relative errors between results calculated from simplified formulae and from FE models are within 10%, which indicates that the proposed formulae are able to provide the theoretical reference for the practical engineering applications.