Circular Concrete-filled Steel Tube Columns Research Articles

Prediction and reliability analysis of ultimate axial strength for outer circular CFRP-strengthened CFST columns with CTGAN and hybrid MFO-ET model

This study develops a novel hybrid machine learning model to estimate the ultimate axial strength and conduct a reliability analysis for outer circular carbon fiber-reinforced polymer (CFRP)-strengthened concrete-filled steel tube (CFST) columns. The experimental datasets are collected and enriched using the conditional tabular generative adversarial network (CTGAN). The column length, the steel properties (cross-section diameter, thickness, and yield strength), the CFRP properties (thickness, tensile strength, and elastic modulus), and concrete strength are selected as input variables to develop the Extra Trees (ET) model hybridized with Moth-Flame Optimization (MFO) algorithm for the ultimate axial strength estimation. The results reveal that the CTGAN can efficiently capture the actual data distribution of CFRP-strengthened CFST columns and the developed hybrid MFO-ET model can accurately predict the ultimate axial strength with a high accuracy (R2 of 0.985, A10 of 0.867, RMSE of 182.810 kN, and MAE of 124.534 kN) based on the synthetic database. In addition, compared with the best empirical model, the MFO-ET model increases the R2 by (6.78% and 13.48%) and A10 by (108.19% and 122.88%) and reduces the RMSE by (68.19% and 66.24%) and MAE by (71.33% and 68.48%) based on real and synthetic databases, respectively. Notably, a reliability analysis is performed to evaluate the safety of the developed MFO-ET model using Monte Carlo Simulation (MCS). Finally, a web application tool is created to make the developed MFO-ET model easier for users to design practical applications.

Investigating the axial compressive behavior of cruciform CFST columns: An experimental study

Concrete-filled steel tube (CFST) columns enhance seismic resistance, enabling lighter-weight structures with improved fire performance. This study investigates the axial performance of cruciform CFST columns using three half-scale experiments. The cruciform sections were internally configured as unstiffened (UnS-CFST), stiffened (S-CFST), and multicell (M-CFST). Failure mode, stress, displacement, ductility, and strength were evaluated to determine the maximum load-bearing capacity. Compared to UnS-CFST columns, S-CFST and M-CFST exhibited improved ductility and axial compressive performance. The study also looks at how the proposed method for cruciform sections compares to existing design standards for square and circular CFST columns, such as AIJ, EC4, GB 50936–2014, CECS 159:2004, ACI 318R-05, and AS3600–2001. A novel method for determining the maximum load capacity of cruciform CFST columns is proposed, achieving an accuracy of approximately 95 % compared to experimental results. This novel method facilitates the design of cruciform CFST columns.

Lateral impact performance of pitting corroded CFST columns for offshore applications

This study investigates the lateral impact performance of circular concrete-filled steel tube (CFST) columns with pitting corrosion. A comprehensive set of 15 CFST specimens was meticulously constructed, including 3 non-corroded specimens used as controls and 12 specimens subjected to varying pitting corrosion conditions. These conditions included different depths, numbers of corrosion pits, and pitting corrosion distributions. Additionally, an extensive Finite Element Analysis (FEA) was conducted to gain detailed insights into the instantaneous dynamic responses of CFST columns with pitting corrosion under lateral impact. The FEA included failure mechanism investigation, stress and strain analyses, bending moment responses, strain rate changes, and energy transformations. The experimental and FEA results reveal that pitting corrosion significantly affects the dynamic behavior of CFST columns, demonstrating reductions in impact force and flexural capacity due to pitting corrosion, and highlighting the influence of corrosion depth, number of pits, and distribution on column behavior. Finally, a simplified model incorporating the effects of pitting corrosion was proposed to estimate the dynamic flexural strength of pitting corroded CFST columns. The results provide valuable insights for designing and assessing the structural integrity of CFST members in marine environments.

Investigation of interfacial bond strength of circular CFST columns based on ordinary and inorganic polymers through advanced machine learning methods

Concrete-filled steel tube (CFST) is a combination of materials, in which the interfacial bond-slip behavior is the prerequisite to reflect the synergistic loading of external steel tube and core concrete. The inorganic polymer concrete within the concrete-filled steel tube (IPCFST) compensates for the drying shrinkage of the concrete and enhances the adhesion at the interface between the steel tube and the concrete. However, the current code is too simple for the bond strength of CFSTs, and the existing theoretical calculation methods are not universally applicable. This paper aims to develop a practical artificial neural network tool for predicting the interfacial bond strength of ordinary CFSTs and IPCFSTs. An efficient prediction model for the bond strength of CFST interfaces was developed using a radial basis function network (RBFNN), with concrete strength, steel tube size, bond length and other factors as the main parameters. Bond performance test data was collected for a sample database of 322 circular CFST columns, including 56 ordinary CFSTs and 263 IPCFSTs. The results show that the Artificial Neural Network (ANN) algorithm can effectively address the bond strength problem of CFST structures and improve the accuracy and density of prediction in the comparative analyses with the measured values and the results of the semi-theoretical formulations. Based on the prediction results of ANN model, a sensitivity analysis of the parameters using Garson's algorithm shows that the diameter-to-thickness ratio and concrete strength significantly affect bond strength for both ordinary CFSTs and IPCFSTs. This study provides a more reliable prediction method and technical support for the engineering design of CFST structures.

Behavior of circular ultra-high-strength concrete-filled steel tube columns subjected to combined high-axial and cyclic lateral loads

The present study examined the seismic performance of circular concrete-filled steel tube (CFST) columns infilled with ultra-high-strength concrete (UHSC >100 MPa) as well as the beneficial effect of embedded spiral confining (SC) reinforcement at high axial load ratios (0.53–0.70) in order to enhance the safety and structural integrity of high-rise buildings. Seven specimens, including four CFST columns and three SC-CFST columns, were investigated under combined high axial and quasi-static cyclic lateral loads. The test parameters included axial load ratio (0.53–0.70), concrete compressive strength (64–111 MPa), embedded spiral confining reinforcement (pitch of 30 mm and 60 mm), and concrete vibration state. The test results demonstrated that adding spiral reinforcement improved the deformation capacity of CFST columns, which was reduced by the increased concrete strength. By embedding spiral confining reinforcement (volumetric ratio 3.3 %), the SC-CFST columns attained a deformation capacity comparable to that of CFST columns with normal concrete (64 MPa) for an axial load ratio of 0.53. The higher axial load ratio and concrete strength of composite columns led to a significant P-Delta moment effect, resulting in a substantial drop in columns' lateral load capacity. Composite columns with UHSC showed a larger contribution from the column base rotation to the specimen's lateral deformation when compared to composite columns with normal-strength concrete because the rigidity offered by UHSC made the column more rigid and reduced its flexural deformation. The unvibrated core concrete of the CFST column did not influence the initial stiffness and energy dissipation capacity. However, during the later stages of loading, the damage in core concrete rapidly accumulated, resulting in instant degradation of the load capacity and stiffness, considerable axial shortening, and poor deformation capacity. The experimental investigation offered a reliable reference on the performance of CFST columns constructed under high-axial load ratios (0.53–0.7) using ultra-high-strength concrete (>100 MPa) and spiral confining reinforcement so as to promote their application in practical engineering.

Structural performance of circular CFST columns with circumferential gap imperfections

The present study investigated the influence of circumferential uniform gap imperfections (≤ 1.0%) on the structural behavior of circular concrete-filled steel tube (CFST) columns under axial compression. The study involved testing 20 CFST columns with circumferential uniform gaps with varying gap ratios (0.2%–1.0%), diameter-to-thickness ratios (18–43), and concrete strength (68.5 MPa and 114 MPa). The presence of uniform gaps (0.2%–1.0%) reduced the confinement effect of steel tube on core concrete, and peak load capacity decreased by 9.0%–24.0%. The normalized concrete strength in high-strength concrete specimens with gap ratios ranged between 0.89 and 0.99, showing no interaction between steel tube and core concrete due to the less deformable nature of high-strength concrete. Core concrete exhibited a combination of vertical splitting and diagonal cracks distributed across the height of specimens with an increase in gap ratio, and local steel tube bulging was dispersed around the edge regions. A theoretical procedure was developed to assess the impact of uniform gaps on the stress state of steel tube and core concrete by determining their respective load contributions. The suggested approach reasonably estimated the gap ratio's nominal influence on the behavior of steel tubes and its considerable influence on the behavior of core concrete. Considering the experimental limitations, gap ratios were broadened through finite element modelling to investigate the gap ratio effect further. After examining the confinement mechanism of CFST columns and finite element results, an analytical formulation to predict the peak load capacity of CFST columns with circumferential uniform gaps was proposed and verified.

Experimental and numerical study on axial compression behavior of slender CFST columns with localized pitting corrosion damage

In order to investigate the axial compression behavior of slender circular concrete-filled steel tubes (CFSTs) with localized pitting corrosion damage, an experimental and numerical study was performed in this paper. In the experimental study, mechanically drilled cylindrical pits were employed to simulate localized pitting corrosion damage. Seven specimens were tested, with six specimens containing corrosion pits located at mid-height and one intact specimen. The experimental results showed that the localized pitting corrosion damage degraded the axial compression behavior of the specimens. Numerical models were developed and validated by the experimental results and used to consider the random characteristics of corrosion pits. A parametric analysis was then performed based on the validated numerical models. It was revealed that the ultimate strength of CFST was influenced by the location and dimensions of the pitting corrosion. Considering the random nature of localized pitting corrosion damage located at the midheight, practical calculation models for predicting the ultimate strength of CFSTs were put forward based on the methods provided in existing codes. On account of the obtained data pool, the predictions were verified against the results from the tests and parametric analysis. In addition, considering the random locations of the pitting region on the surface of the member, a method based on the controlling section was proposed to determine whether the corrosion should be considered and to calculate the ultimate strength.

Experimental research on load separation of concrete-filled circular steel tube short columns

In recent years, scholars from various countries have conducted extensive experiments and analytical studies on the axial compressive behavior of circular concrete-filled steel tube (CFST) columns. However, the existing research has been based on overall loading analysis of circular CFST columns, making it difficult to accurately measure the loads borne by the steel tube and the core concrete separately. In order to better study the axial compressive behavior of circular CFST columns, this paper adopts the load separation device proposed by Hong-Song Hu and prepares 16 specimens with different concrete strengths for axial compression tests, directly measuring the load components of circular CFST columns under axial compression. The feasibility of the superposition principle is revealed at the experimental level. Furthermore, the compressive strength of the concrete and the compressive strength of the steel tube in circular steel tube concrete columns are analyzed. The results indicate that there is a certain discrepancy between the calculated steel tube strength based on existing formulas and the experimental values. However, for safety considerations, a reasonable estimation of the steel tube compressive strength can be made. Utilizing the measured stress-strain values of concrete and steel, the existing stress-strain models are evaluated, and a more reliable stress-strain model is established.

Lateral impact behaviour of CCFT columns with spherical-cap gap imperfection: Numerical modelling and design method

To clarify the influence of gap imperfection on the impact behaviour of the concrete-filled steel tube (CFT) column, this paper performs numerical modelling on the mechanical responses of the circular CFT columns holding spherical-cap gaps (CCFT-SG) under lateral impact load. The effects of gap ratio, axial compression ratio, impact position, diameter/thickness ratio, boundary condition and material strength on the energy dissipation (Ea), the maximum (Fm) and equivalent impact forces (Feq), the peak (δm) and residual lateral deflections (δr) are analyzed after establishing and validating the finite element (FE) model. The typical failure pattern, time-history curve and contact response between the tube and concrete of the laterally impacted CCFT-SG column are revealed as well. The result declares that the overall failure morphology of the CCFT-SG column imposed with lateral impact showing as overall bending, is similar to that of the common CFT column, but distinct local depression is obtained because of the existence of spherical-cap gaps. With the gap ratio increasing, the Feq, Fm and Ea decrease gradually, while the δm and δr rise slowly. The calculation formulae for predicting the dynamic impact force and resistance of the CCFT-SG column are presented and validated against the existing test and numerical results.

Equivalent stress-strain models of components in high-strength concrete-filled circular steel tube columns

Nine circular concrete-filled steel tube (CFST) columns with 109 MPa concrete were tested under eccentric axial loading to derive the equivalent axial stress-strain models of the steel tube and concrete. Based on the measured strain data and the theory of elasticity and plasticity, the progressions of the axial and hoop stresses at different locations of the steel tube section were obtained. For the compression side of the steel tube, the hoop stress was developed at or after yielding; then, the ratio of the axial stress to the effective stress, σsa/fe, gradually decreased to a value of around 0.77. For the tension side of the steel tube, σsa/fe continued to increase after yielding and kept constant when σsa/fe reached a value of approximately 1.15. Using the developed axial stress-strain model of the steel tube, the equivalent axial stress-strain relationship of concrete was determined by matching the axial load-vertical displacement curve obtained from the fiber model analysis to that from the test. The confinement index, ξ, mainly influences the peak compressive stress and strain of concrete, whereas the eccentricity ratio has some influence on the descending branch of the stress-strain curve. The fiber model with the proposed stress-train models of steel and concrete can well simulate the behavior of circular CFST columns with high-strength concrete under compression-flexural loading when 0.35 ≤ ξ ≤ 0.85, 0.14 ≤ e/D ≤ 0.68, and 3.8 ≤ Le/D (Le is the effective length of a column) ≤ 10.6.

Axial compressive behavior of circular composite columns with external confinement

With the advance of externally confined composite columns, a generic model that can predict the ultimate axial compressive strength of both circular concrete-filled steel tube (CFST) and concrete-filled double skin steel tubes (CFDST) short columns with external confinement is very attractive. For this purpose, a rich experiment database of composite columns is assembled, guides to build up this database are outlined, and its limitations are also summarized. Based on some fundamental considerations, a simple formula for estimating ultimate axial compression of circular composite short columns is proposed first. The hoop and longitudinal stresses of outer and inner (if any) steel tubes are then determined by the stress analysis, from which the assumption frequently used in previous studies that the sandwiched concrete in a CFDST column is under uniform confinement is demonstrated to be unreasonable. Besides, the additional external confining pressure provided by external confinement in the form of steel spirals, rings, jackets, or tie bars is thoroughly investigated. Further, to comprehend the triaxial strength of infilled concrete in both CFST and CFDST columns, a novel concept of equivalent confining stress that can reflect both uniform and non-uniform confinement effects is defined, with which a modified Power-law failure criterion is established. Model validations illustrate that this generic model can reasonably estimate the strength of externally confined CFST and CFDST columns. Although it currently slightly underestimates the strength of ring-enhanced CFDST columns, this limitation can be easily overcome by recalibrating some coefficients without rebuilding the proposed framework.

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 circular concrete-filled steel tube columns reinforced with inner latticed steel angles

The seismic behavior of circular concrete-filled steel tube (CFST) columns with inner latticed steel angles under combined axial load and reversed cyclic horizontal load was studied in this paper. A total of 8 specimens was tested, including two CFST specimens and six latticed steel angles reinforced CFST specimens. The main parameters studied were the diameter-to-thickness ratio of steel tube, the cross-sectional area of inner latticed steel angles and the axial compression ratio. Firstly, the load-displacement curves and load-strain curves were obtained experimentally; secondly, the failure modes, hysteretic behavior, skeleton curves, stiffness degradation, ductility index, hysteretic energy dissipation capacity were analyzed; thirdly, the seismic performance of the tested specimens were simulated by the established finite element (FE) models, and parametric studies were subsequently performed; finally, the modified calculation method for the horizontal bearing capacity was proposed. The research results showed that the failure of the composite columns was caused by the local buckling of the latticed steel angles and steel tube, and the latticed steel angles could effectively participate in the overall loading process. It was also found that latticed steel angles are able to improve the energy dissipation capacity.

Evaluation of Confining Pressure Models for Circular Concrete-Filled Steel Tube Short Columns under Concentric Loading

It is well known that the confinement effect provided by the steel tube significantly increases the strength and ductility of circular Concrete Filled Steel Tube (CFST) columns under concentric loading. The lateral pressure is an important factor to calculate the strength enhancement of CFST columns. To reliably predict the ultimate strength of circular CFST columns, many models have been developed for predicting the lateral pressure due to the confinement effect. This paper aims to evaluate some of these confining pressure models. The values of the compressive strength of confined concrete and lateral confining pressure of circular CFST short columns were calculated using these existing models and were compared with those obtained from previous test results. In addition, a comparison between the ultimate loads predicted by these models and by Eurocode 4 (EC4) was carried out. Based on the comparison results, some suitable models for circular CFST short columns with the use of normal-strength, high-strength, and ultra-high-strength concrete were indicated.

Combining Artificial Neural Network and Seeker Optimization Algorithm for Predicting Compression Capacity of Concrete-Filled Steel Tube Columns

Accurate and reliable estimation of the axial compression capacity can assist engineers toward an efficient design of circular concrete-filled steel tube (CCFST) columns, which are gaining popularity in diverse structural applications. This study proposes a novel methodology based on computational intelligence for estimating the compression capacity of CCFST. Accordingly, a conventional artificial neural network (ANN) is hybridized with a metaheuristic algorithm called the seeker optimization algorithm (SOA). Utilizing information such as the column’s length, compressive strength of ultra-high-strength concrete, and the diameter, thickness, yield stress, and ultimate stress of the steel tube, the capacity of the column is predicted through non-linear calculations. In addition to the SOA, the future search algorithm (FSA) and social ski driver (SSD) are used as comparative benchmarks. The prediction results showed that the SOA-ANN can learn and predict the compression capacity pattern with high accuracy (relative error < 2.5% and correlation > 0.99). Also, this model outperformed both benchmark hybrids (i.e., FSA-ANN and SSD-ANN). Apart from accuracy, the configuration of the SOA-ANN is simpler owing to the smaller population recruited for the optimization task. An explicit formula for the proposed model is developed, which, owing to its observed efficiency, can be reliably applied to CCFST columns for the early estimation of the compression capacity.

Seismic behavior of steel-plate encased concrete shear wall with paralleled circular CFST columns: Laboratory test and numerical simulation

Aiming to improve the structural behavior of high-rise buildings, a steel-plate encased concrete shear wall with parallel circular concrete-filled steel tube columns (P-CFST-SCSW) is proposed and investigated by experiments and numerical studies in this study. All seven specimens were conducted and tested under reversed cyclic force to explore the influences of different design parameters, including axial compression ratios, steel tube thicknesses, spacing-thickness ratios, and shear span ratios. The failure modes, hysteresis behavior, strength and stiffness degradation, energy dissipation were thoroughly recorded and compared in detail. Results indicated that all specimens have experienced the failure process of boundary steel tubes buckling, steel plates buckling and concrete crushing. Results also showed that the bearing capacity and deformation capacity of proposed composite walls was excellent. The peak force and initial stiffness of P-CFST-SCSWs were improved by reducing the shear span ratio and increasing the axial compression ratio, while the stiffness degradation and ductility quickly deteriorated. The increased thickness of circular steel tubes considerably improves the seismic behavior of P-CFST-SCSWs. Finally, the numerical model was established to further investigate the effect of the concrete strength, steel yielding strength, and circular CFST columns number on lateral behavior of P-CFST-SCSWs.

Axial compressive performance of concrete-filled steel tube stub columns with high-strength spiral confined concrete core

Concrete-filled steel tubes (CFSTs) are widely used as hybrid columns. However, rectangular/square CFST columns are less ductile and have lower strength than circular CFST columns. To solve this problem, a novel hybrid column, namely, a high-strength steel (HSS) spiral confined CFST (HSSS-CCFST or CCFST) column, was recently proposed and investigated in this study. The spiral confinement can enhance the axial compressive performance of concrete, including load capacity, deformability and especially secondary stiffness. Monotonic axial compressive tests were conducted on 12 CCFFT columns, a steel concrete FRP concrete (SCFC) column and a CFST column. The failure modes, failure processes and mechanical behaviour of the CCFFT columns were compared with those of the SCFC and CFST columns. The relationships between the states of the columns and the materials were analysed. In addition, 3D laser scanning was performed to obtain the deformation modes. Finite element (FE) analysis of the CCFST column was conducted using commercial finite element software (Abaqus). To improve the accuracy of the simulation, the constitutive models of spirals with different strength grades were modified using the section strip method and considering the residual stress from manufacturing; the constitutive model of concrete was also improved. The results of the FE analysis agreed well with the failure modes of the components in the CCFST and the stress–strain behaviours. A parametric analysis was conducted to determine the influence of the strength and dimension parameters, and finally, the design method of the axial load capacity of the CCFST was obtained by fitting the results from the experiments and the parametric analysis.

New Fuzzy-Heuristic Methodology for Analyzing Compression Load Capacity of Composite Columns

Predicting the mechanical strength of structural elements is a crucial task for the efficient design of buildings. Considering the shortcomings of experimental and empirical approaches, there is growing interest in using artificial intelligence techniques to develop data-driven tools for this purpose. In this research, empowered machine learning was employed to analyze the axial compression capacity (CC) of circular concrete-filled steel tube (CCFST) composite columns. Accordingly, the adaptive neuro-fuzzy inference system (ANFIS) was trained using four metaheuristic techniques, namely earthworm algorithm (EWA), particle swarm optimization (PSO), salp swarm algorithm (SSA), and teaching learning-based optimization (TLBO). The models were first applied to capture the relationship between the CC and column characteristics. Subsequently, they were requested to predict the CC for new column conditions. According to the results of both phases, all four models could achieve dependable accuracy. However, the PSO-ANFIS was tangibly more efficient than the other models in terms of computational time and accuracy and could attain more accurate predictions for extreme conditions. This model could predict the CC with a relative error below 2% and a correlation exceeding 99%. The PSO-ANFIS is therefore recommended as an effective tool for practical applications in analyzing the behavior of the CCFST columns.

Iterative Finite Element Analysis of Concrete-Filled Steel Tube Columns Subjected to Axial Compression

Since laboratory tests are usually costly, simulating methods using computers are always under the spotlight. This study performed a finite element analysis (FEA) using iterative solutions for simulating circular and square concrete-filled steel tube (CFST) columns infilled with high-strength concrete and reinforced with a cross-shaped plate (comprising two plates along the columns that divide the hollow columns into four equal sections) with and without opening. For this reason and for validation purposes, the columns had length of 900 mm, width/diameter of 150 mm and wall thickness of 3 mm. In this study, unlike in some other studies, the cross-shaped plate was assumed to be fixed at the top and the bottom of a column, and the columns were subjected to axial compression pointed in the center. The outcomes revealed that the cross-shaped plate could improve the axial strength of both circular and square CFST columns; however, the structural performance of the square CFST columns changed: local outward buckling was observed after inserting the cross-shaped plate. By inserting an opening on the cross-shaped plate, the bearing capacity of the circular CFST columns was further improved, while the square CFST columns experienced a decline in their ultimate bearing capacity compared with the corresponding models without the opening. The lateral deflection also improved for the circular CFST columns by adding the reinforcement. However, for the square CFST columns, while it initially improved, increasing the thickness of the cross-shaped plate inversely influenced the lateral deflection of the square CFST columns. The results were also compared with some available codes, and a good agreement was achieved with those outcomes.

Finite element simulation of load bearing capacity of circular CFST long columns with localized corrosion under eccentric load

In order to study the influence of local corrosion on the load-bearing capacity of circular concrete filled steel tube (CFST) long columns under eccentric compression, a numerical model was established by using the commercial finite element software ABAQUS. The influence of corrosion site, corrosion volume rate and corrosion area rate on the whole process of load and deformation was discussed, and the sensitivity analysis of the steel strength, concrete strength, eccentricity, steel tube wall thickness and slenderness ratio was performed. It was show that corrosion site and corrosion volume rate have greater impact on ultimate load bearing capacity of circular CFST long columns with localized corrosion, but corrosion area rate has less impact. Under the same corrosion volume rate, the load bearing capacity of CFST columns with localized corrosion at both ends is greater than that at one end which is greater than that at the middle segment. Steel strength, concrete strength, eccentricity, steel tube wall thickness and slenderness ratio can all affect the bearing capacity of the column and corrosion can further degrade it.