Steel-concrete Composite Columns Research Articles

Investigation of double-skinned square steel-concrete composite columns with in-built square cores

ABSTRACT Double-skinned steel-concrete composite columns are famous nowadays in the construction industry because of their structural advantages. The analysis of the performance of double-skinned composite columns with two steel skins of the outer and inner tube, in addition to an in-built steel core in-filled with concrete, was attempted. Steel skins can serve multiple functions, notably defining the geometry of the concrete column and preventing cracks from tensile pressure. This article consists of the research work, numerical and experimental investigation, of the behaviour of Double-Skinned Square Composite Columns (DSSCC) with square cores in-filled with concrete under axial compressive load. The square steel tubes are of size 150 and 50 mm with 6 and 3 mm thickness of outer and inner tubes, respectively, and a height of 500 mm characterized by an inner core of 1 mm thickness. The steel tube considered in the current numerical study (using Abaqus 6.14) is of grade Fe250, Fe350 and Fe415, and in-filled concrete is of grade M20, M25, M30, M35, M40 and M45. The steel tube considered in the present experimental study is of grade Fe250, in addition to the steel cores, which are made of grade A1008 cold-formed steel. The average compressive strength of the concrete used in an experimental study, after 28 days of curing, is measured as 26.07, 32.89 and 40.29 N/mm2. The current study was performed to find the axial compressive behaviour, ultimate load, load versus vertical and horizontal deflection behaviour and corresponding stress and strain value and failure modes. Stiffness, ductility ratio and energy absorption capacity were determined from the observed test values. The results show that increasing concrete compressive strength improves the load-carrying capacity of the column. The experimental and numerical results were discussed and validated.

Experimental study on monotonic loading of joint of multi-limb assembled cold-formed thin-walled steel concrete composite column and H-shaped steel beam

Experimental study on monotonic loading of joint of multi-limb assembled cold-formed thin-walled steel concrete composite column and H-shaped steel beam

Compression performance of L-shaped multi-limb assembled cold-formed thin-walled steel concrete composite column

Compression performance of L-shaped multi-limb assembled cold-formed thin-walled steel concrete composite column

Experimental and theoretical analysis of L-shaped partially encased thin-walled steel-concrete composite columns under axial compression

Experimental and theoretical analysis of L-shaped partially encased thin-walled steel-concrete composite columns under axial compression

Preliminary findings from experimental study on blast performance of steel-concrete composite columns

Abstract The use of steel-concrete composites in blast resistance has gained importance in the recent years, since concrete is not able to resist higher explosive charges. The authors have designed an experimental device to test steel-concrete composite columns subjected simultaneously to axial and blast loading. The experimental device in a shape of a closed steel frame allows to test plain steel columns, composite steel-concrete columns and composite steel-using ultra-high performance fiber-concrete (UHPFRC) columns. The specimen is loaded with 800f of explosive charge while subjected to axial compressive loading. The response of the specimen is acquired using photonic-doppler velocimetry (PDV). The paper presents preliminary results from the first run of the experiment documenting the benefits of composite action on blast resistance of the tested columns. The use of UHPFRC also showed its beneficial effects. This paper presents preliminary findings from the experimental program.

Study of the fire resistance of partially encased composite steel-concrete columns according to Eurocode 4

In this paper, the behavior of partially encased steel and concrete composite columns without fire protection exposed on four sides to the standard fire and under axial loading was studied using the simplified calculation model of the Eurocode4 (EC4) method. The main objectives of this study are: first to evaluate the temperature of the different components of the column section as well as the variation in the characteristics of the materials constituting them (strengths and Modulus of elasticity); and then analyze the influence of several parameters, such as the section size, the reinforcement rate, the buckling length and the mechanical strengths of the steel and concrete on the ultimate fire resistance. The results show that the dimensions of the section, the reinforcement rate and the buckling length have a significant influence on the fire resistance. On the other hand, the concrete strength, the structural steel grade and the reinforcing steel grade have a moderate influence.

Numerical analysis of flexural behaviour of UHPC-CFTS columns as enclosure supports for electrical substations

Abstract This study establishes a finite element analysis model of ultra-high-performance concrete (UHPC) encased concrete filled steel tube (CFST) composite columns under combined compression and bending. Appropriate constitutive models and element types are selected as the basis. The finite element model simulates the test results of steel-concrete composite columns, and the applicability of the model is verified by comparison with existing test data of UHPC encased CFSTs. On the basis of demonstrating model reliability, the full-range load-deformation curves of UHPC encased CFSTs with different concrete strengths under compression-bending are compared. The failure modes and material stress distributions are analyzed to elucidate the influence mechanism of the UHPC on the flexural performance of UHPC encased CFSTs under combined compression and bending. The results show that compared to normal concrete, UHPC can effectively improve the flexural capacity of UHPC encased CFST columns. Owing to the addition of steel fibers, the failure mode of UHPC encased CFSTs under combined compression and bending is more integral compared to normal concrete. The research results of this study can provide references for the performance evaluation and design of UHPC encased CFSTs in the structural enclosures for electrical equipment in high/low voltage substations.

Behaviour and design of prestressed stayed circular concrete-filled double skin steel tubular (PS-CCFDSST) columns under axial compression

An innovative type of steel-concrete composite column, named the prestressed stayed circular concrete-filled double skin steel tubular (PS-CCFDSST) column, is introduced in this study, aiming to achieve both structural efficiency and economic advantages. Numerical simulation and theoretical analysis on the axial compressive behaviour of PS-CCFDSST columns were carried out, to understand and reveal their fundamental working mechanisms. Nonlinear finite element analysis (FEA) utilising ABAQUS was performed and validated against collected test data of CCFDSST columns and PS columns. Properly designed PS-CCFDSST columns could gain cost savings of over 30 % while maintaining identical load-bearing capacity as prestressed stayed hollow steel tube (PS-HST) columns with the same steel usage. The effects of initial pretension, nominal steel ratio, hollow ratio, column’s slenderness ratio, relative length of struts, column diameter, strut diameter and cable area on the buckling mode and buckling capacity of PS-CCFDSST columns were evaluated via parametric studies. The stiffness ratio β could be used as an index to comprehensively assess the structural efficiency of PS-CCFDSST columns, and a critical threshold of β = 2 corresponds to the transition between symmetric and anti-symmetric buckling modes. Linear calculation formulae for the theoretical buckling capacity and optimal initial pretension of PS-CCFDSST columns were derived. Finally, practical design equations for predicting the column’s buckling capacity were developed, and recommended values for the actual optimal initial pretension and other primary parameters were provided for PS-CCFDSST columns under axial compression. This study, for the first time, provides the fundamental mechanical behaviour, identification of the critical stiffness ratio for buckling mode transition, and design framework for buckling capacity of the PS-CCFDSST column, which is useful for advancing theoretical exploration and informing engineering practices for this new column type.

Seismic Performance of Cross-Shaped Partially Encased Steel–Concrete Composite Columns: Experimental and Numerical Investigations

Special-shaped partially encased steel–concrete composite (PEC) columns could not only improve the aesthetic effect and room space use efficiency, but also exhibit good mechanical performance under static load when used in multi-story residential and office buildings. However, research on the seismic performance of special-shaped PEC columns is insufficient and urgently needed. To investigate the seismic performance of cross-shaped partially encased steel–concrete composite (CPEC) columns, three CPEC columns were designed and tested under combined constant axial load and lateral cyclic load. The test results show that the CPEC columns had good load capacity and ductility, and that the columns failed because of concrete crushing and steel flange buckling after the yielding of the steel flange. The plump hysteresis loops indicated that the CPEC column also had good energy dissipation capacity. Due to the constraint of hydraulic jacks, increasing the load ratio would decrease the effective length, thereby increasing the load capacity of the CPEC column and decreasing the ductility. A finite element model was also established to simulate the response of the CPEC columns, and the simulated results agree well with the experimental results. Thereafter, an extensive parametric analysis was performed to study the influences of different parameters on the seismic performance of CPEC columns. For the CPEC column with an ideal hinged boundary condition at the top, its lateral load capacity gradually decreases with the growth of the load ratio and link spacing and increases with the rise of the steel yield strength, concrete compressive strength, flange and web thickness, and sectional aspect ratio. This research could provide a basis for future theoretical analyses and engineering application.

Experimental study on axial compressive behavior of concrete-filled corrugated steel tubular columns

Concrete-filled corrugated steel tubular (CFCST) column is a novel type of steel-concrete composite column, comprising four corrugated steel plates, four square-section steel bars at the corners, and infilled concrete. The transversely placed corrugated steel plates can effectively prevent their premature local buckling, release the axial load, and provide lateral confinement effects on the infilled concrete. This paper investigated the axial compressive behavior of CFCST columns through experimental, numerical, and theoretical approaches. Experiments were conducted on 20 specimens, focusing on their axial load-resistant behavior. The specimens demonstrated excellent axial bearing capacity, ductility, and residual bearing capacity. Besides, the mechanical behavior of corrugated steel plates throughout the loading process was analyzed through the development of the horizontal and vertical strains. Furthermore, a finite element (FE) model was developed to simulate the axial compressive behavior of CFCST columns, which was validated against the experimental data. The FE model was used to analyze the compressive behavior of each part in CFCST columns, revealing that the infilled concrete and steel bars primarily bear the axial load, while the corrugated steel plates mainly provide lateral supports to the infilled concrete. Finally, a simplified method for calculating the critical width of corrugated steel plates and a formula for the axial bearing capacity of CFCST columns were proposed. It was indicated that the limiting width-to-thickness ratio of the corrugated steel plates was larger than that of the steel elements in conventional CFST columns. These formulas were demonstrated to be accurate enough and suitable for the engineering designs.

Fire test and simulation of circular steel tube confined steel-reinforced concrete columns

Steel tube confined steel-reinforced concrete (STCSRC) columns are novel steel-concrete composite columns where the steel tubes are disconnected at beam-column connections. Few researches have been conducted on the fire behaviour of STCSRC columns by now, though there are some relevant studies on the fire performance of steel-reinforced concrete-filled steel tubular (SR-CFST) columns. However, the mechanical behaviour of STCSRC columns under fire exposure differs from that of SR-CFST columns due to the discontinuous external steel tube. It is essential to carry out a study on the fire performance of STCSRC columns. The fire tests of four axially loaded STCSRC columns were carried out in this paper, and the failure mode, distribution of cross-sectional temperature, fire resistance, and lateral deflection were discussed. A finite element model was developed and validated with test results, and then a parametric analysis of the STCSRC stub and slender columns under fire exposure was performed. The load ratio, steel tube strength, the area ratio of steel tube to concrete, and slenderness ratio have an adverse effect on the fire resistance of STCSRC columns, whereas cross-sectional dimension, area ratio of steel section to concrete, and strength of steel section have a favourable impact. Concrete strength has a different influence on the fire resistance of STCSRC stub and slender columns. Finally, based on the specifications JGJ/T 471-2019 and EN 1994-1-2, simplified calculation methods for assessing the fire resistance of STCSRC columns were proposed.

Erratum for “Behavior and Design of Steel-Concrete Composite Columns Subjected to Combined Axial Compression and Biaxial Moment”

Erratum for “Behavior and Design of Steel-Concrete Composite Columns Subjected to Combined Axial Compression and Biaxial Moment”

Experimental investigation and design method of axial compression behavior of T-shaped partially encased steel-concrete composite stub columns

The implementation of special shaped Partially Encased Steel-concrete Composite (PEC) columns represents a viable approach to avoid the protruding of PEC columns with conventional cross-sections in tall buildings. Nevertheless, there is a lack of clarity regarding the load-carrying capacity and failure mechanisms associated with special shaped PEC columns. To comprehensively investigate the mechanical behavior of special shaped PEC columns under axial loading, this paper conducts an experimental analysis focusing on the compressive behavior of 9 T-shaped PEC (TPEC) short columns. The study examines the influence of critical design factors, including the content of section steel, spacing between transverse links, aspect ratio of the section, and the strength of concrete, on the axial load-carrying capacity of the members. Subsequently, the failure mode, ultimate load, initial stiffness, strain response, ductility index, and strength characteristic index of TPEC short columns were thoroughly explored. The results show that TPEC short columns exhibited damage patterns characterized by flange buckling, concrete spalling, accompanied by buckling of some transverse links and fracture of connecting joints. The steel ratio and transverse links spacing have substantial influence over the ultimate capacity and ductility of the columns. Notably, an augmentation in the steel ratio leads to an increase in both the ultimate capacity and ductility, while an increase in transverse links spacing results in a decrease in these characteristics. Comparatively, the section aspect ratio and has a relatively minor impact on the capacity and ductility. Additionally, it can be observed that the strength of concrete has a significant influence on the load-bearing capacity of short columns, while its effect on ductile behavior remains relatively insignificant. Finally, the applicability of the current design guidelines (i.e. the ACI318-14, Eurocode 4 and T/CECS719-2010 codes) are evaluated and a new design method for assessing the axial compression resistance of TPEC stub columns based on the constrained partitioning theory and the principle of superposition is proposed. This study can serve as a substantial theoretical foundation for the engineering utilization of TPEC short columns.

Behavior of Two-Chord Steel–Concrete Composite Columns under Axial Compression

Behavior of Two-Chord Steel–Concrete Composite Columns under Axial Compression

Seismic behavior and mechanism of rectangular steel-concrete composite column with three cavities

This paper proposes a rectangular steel-concrete composite column (RSCC) with three cavities, which has a good architectural function. The composite column consists of steel tubes at both ends, steel plates in the middle, and concrete in the cavity. Five RSCC with three cavities were tested to investigate the seismic performance of the column width and headed studs. It was found that the specimens all exhibited flexural damage in the form of flexural tearing of the steel tube/plate and crushing of the concrete in the steel tube cavity. As the column width increases, the load bearing ratio and the percentage of shear displacement in the middle cavity of the specimen increase. The use of headed studs in RSCC with three cavities delay the stiffness degradation of the specimens, and the ductility of the specimens with column width of 400 mm and 500 mm set with headed studs increased by 10.1% and 4.6%, respectively, compared to that of the specimens without headed studs. In addition, a finite element model of the RSCC with three cavities was established, and the finite element analysis results matched well with the experimental hysteresis curves and damage characteristics. A simplified lateral force calculation method was established, and the average error between the predicted values and the corresponding test results for each specimen was 6.1%, which verified the applicability of the calculation model and provided a reference for the engineering application of the RSCC which has good function and performance.

Investigation the influence of geometric parameters on the bearing capacity of partially encased composite columns in fire condition according to Eurocode 4

In this article the method to determine the bearing capacity of composite steel-concrete columns in fire conditions according to Eurocode 4 (EC4) was introduced. Some work examples are presented to clarify the influence of geometric parameters (effective length, axis distance of reinforcement bar) on the bearing capacity of partially encased composite columns in fire condition.

Axial compression behaviour and design of square tubed steel reinforced-concrete stub columns after fire exposure

The tubed steel reinforced-concrete (TSRC) column is an innovative type of steel-concrete composite column, the steel tube of which mainly provides confinement to concrete core without sustaining axial load directly. This paper presents the axial compressive behaviour of square TSRC stub columns after ISO 834 standard fire exposure, experimentally and numerically. Eighteen square TSRC stub columns were heated and cooled and subsequently loaded to failure under axial compression. The influences of heating time, concrete compressive strength and steel tube area ratio on the load vs. displacement response, failure mode, residual capacity and stiffness of the tested columns were investigated. Finite element analysis (FEA) models were then developed and validated against test results. The working mechanism, e.g. confinement effect and axial force distribution within the composite section, was studied via parametric studies. Both the residual ultimate capacity and axial stiffness of square TSRC stub columns decrease significantly with the increase in heating time. The negative effect of fire exposure on residual stiffness is more significant than on the residual capacity. Finally, practical equations for determining the residual ultimate capacity and residual compressive stiffness of square TSRC stub column were proposed, which remain consistent with the ambient-temperature methods given in current design standard.

Axial compressive behavior of the PEC slender columns with lightweight aggregate concrete

To greatly facilitate hoisting and assembly of prefabricated partially encased steel-concrete composite (PEC) columns, lightweight aggregate concrete (LAC) is applied into the PEC columns to form the partially encased composite columns with lightweight aggregate concrete (PEC-LAC). This paper reported experimental studies on the axial compressive behavior of PEC-LAC columns with various slenderness ratios. Following this, finite element (FE) modeling methods considering geometrical and residual stress imperfections were developed to reproduce the test responses. FE analysis was carried out to investigate the effect of geometrical and material parameters on PEC-LAC slender columns subjected to axial compression along the minor axis and major axis. It was found from the contact stress analysis that PEC-LAC slender columns with axial loading along the major axis provide a stronger confinement effect than that with axial loading along the minor axis. Based on the comparison of reduction factors between the test/FE and calculated results, the buckling curve of AISC 360 and the buckling curve (b) of T/CECS 719 can economically and conservatively describe the buckling curve of PEC-LAC slender columns regardless of the flexural buckling direction; the buckling curves (b) and (a) of EC4 were recommended to predict buckling curves of PEC-LAC columns with flexural buckling about the major and minor axis, respectively.

Parameter Selection for Concrete Constitutive Models in Finite Element Analysis of Composite Columns

Concrete, as a complex and anisotropic material, poses challenges in accurately simulating its behavior in numerical simulations. This paper focuses on selecting an appropriate constitutive model for simulating the behavior of a steel–concrete composite column using finite element analysis under compression and push-out tests. Two models are analyzed and compared, namely, Drucker–Prager and concrete damage plasticity. The results demonstrate that the concrete damage plasticity model outperforms the Drucker–Prager model in all six test cases, indicating its superior accuracy in capturing the composite column’s behavior. This study enhances the reliability of numerical simulations for steel–concrete composite structures by choosing the most suitable constitutive model, parallel with extensive sensitivity analysis and model calibration. The findings emphasize the significance of meticulous model selection and precise parameter definition for achieving accurate predictions of concrete behavior. This research contributes to advancing the understanding and modeling of concrete’s intricate behavior in structural analyses.

Seismic Evaluation of Building having Steel Concrete Composite Columns and RC Beams

Abstract: Steel concrete composite structures are gaining popularity due to the advantages they offer over the conventional reinforced concrete and steel structures like the ease and speed of construction. In the light of this, it becomes essential to understand the behaviour of this type of structures when used in buildings. This study mainly focuses on the use of building frame consisting of steel-concrete composite column section with the reinforced concrete beams. To achieve this objective, the seismic analysis of the buildings was chosen for evaluating the performances of the buildings designed and analyses using Indian standards. The building selected for the study was rectangular in plan andhad an elevation of 30 meters with no plan or vertical irregularity present. The gravity loads considered for the building are in compliance with the IS 875 Part 1 and IS 875 Part 2. However, the gravity loads used in case of both buildings were kept to be same as the prime focusof the study was seismic analysis. The materials used for the design of the building with respect to Indian standards are E345 grade of steel and M30 grade of concrete. Various codes of practices including IS 456, IS 11384, IS 1893 and IS 13920 have been used throughout the study in case of the building designed and analysed with respect to Indian standards. The assumptions regarding the seismic characteristics of the buildings are also selected of the same nature for both the buildings. A finite element modellingbased software ETABs is used to carry out the design and analysis for the buildings. The buildings were designed with respect to the selected gravity loads and the seismic loads to obtain the section details to be used for seismic analysis. The building with finally obtainedsection sizes is used for carrying out the nonlinear analysis. This includes both the nonlinear static and nonlinear dynamic analysisas they both have their respective advantages in predicting the behaviour of the structure. For carrying out nonlinear analysis both material as well as geometric nonlinearity is considered. In case of the nonlinear dynamic analysis, the ground motions with respect to the guidelines of FEMA P695 and ASCE 7-16 were selected and scaled to perform the analysis. A total of 11 time histories were considered for NLTHA to have a thorough analysis. Various factors such as thecapacity curves, story displacements, base shears and story drifts were considered for evaluation of the seismic performance of both the buildings. The results obtained from the analysis of both thebuildings are represented in the form of tables and graphs, and are compared with each other to study the differences observed. It can be concluded that the buildings designed composite columns offers a better ductility and thus is more earthquake resistant