Steel-concrete Composite Sections Research Articles

Utilization of Waste Materials in Concrete Filled Steel Tubular Columns

The idea of this particular study is to utilize waste materials in an effective manner so as to give strength to tubular sections. Steel-Concrete composite construction has emerged as one of the fastest methods of construction in India. The inherent advantage of the steel-concrete composite section lies in that the two principal elements-the steel and the concrete are normally used in a manner so that full potential of both may be realized and the best utilization of their respective properties can be made. In this paper, an attempt was made with steel tubular columns in-filled with plain concrete, partial replacement of fine aggregate by fly ash & quarry dust and coarse aggregate by rubber, slag from steel industry, granite and construction & demolition (C&D) debris concrete. The column specimens are to be tested under axial compression to investigate the effects of waste materials. The effects of steel tube dimensions and the strength of concrete are examined. 24 specimens were tested with strength of concrete as 20 MPa and D/t ratio 23.65. The columns were 113.5 mm outer dimension and 4.8 mm in thickness are 300, 600 & 900 mm in length. The test results are to be compared with the values predicted by Eurocode4, Australian Standards and American Codes and new theoretical models will be suggested for the design. From the test results it was observed that the load carrying capacity of steel tubular columns filled with various waste materials concrete is greater than the conventional concrete.

Flexural performances of steel–concrete composite section of self-anchored suspension bridge: Experimental and theoretical research

This paper aims to clarify the flexural performance and the cracking load, the ultimate bearing capacity calculation theories of the steel–concrete composite section of the self-anchored suspension bridge. A refined local finite-element (FE) model of the steel–concrete composite section was built to evaluate the mechanical performance of key parts under three unfavourable load conditions. A test model of the steel–concrete composite section with a length × width × height of 7 m × 1.833 m × 1.2 m was fabricated according to the scale of 1: 3, and a four-point negative bending test was carried out. The test results show that the test model is in the elastic stage, and the residual displacement ratio is 0.7 % under the design load condition. Under the overload condition (2.3 times the design load), the experimental model is in the elastic–plastic stage, and the residual displacement ratio is 19 %. At the same time, the stress of each component still meets the requirements. Under the two conditions, the deformation angle of the composite section is small, and the stiffness transition is stable. The relative slip between the top steel plate and the concrete in the composite section is small (no more than 0.25 mm). The stress of the top steel plate and bottom steel plate of the composite section gradually decreases during the transfer from the steel stiffening beam to the concrete side. The bearing plate is the main bearer of the force transmission of the steel–concrete composite section, accounting for about 51.24 %, while the top steel plate, bottom steel plate and shear connectors share the remaining load. The steel–concrete composite section of the test model has reasonable force, smooth force transmission and good deformation coordination performance. In addition, the calculation methods of cracking load and ultimate bearing capacity of the prestressed steel–concrete composite section were proposed. The theoretically calculated value of the ultimate bearing capacity of the steel–concrete composite section is in good agreement with the FEA value, and the difference does not exceed 10 %.

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

Experimental study on the flexural performance of steel-concrete composite section of self-anchored suspension bridge

In order to study the flexural performance of the steel-concrete composite section of self-anchored suspension bridge, a test model of the steel-concrete composite section was fabricated according to the scale of 1 : 3 based on the Wushui Bridge, and a four-point negative bending test was carried out. The results show that the residual displacement ratio is 0.7%, and the experimental model is in the elastic stage under the design load condition, which incidate that the component is safe under normal service condition. Under the overloading condition, the residual displacement ratio is 19%, the experimental model is in the elastic-plastic stage, but the stress of materials still meets the requirements. Under the two conditions, the deformation angle of the composite section is small and the stiffness transition is stable. The relative slip between the steel plate and concrete in the composite section is small (no more than 0.25 mm). The stress in the top steel plate and bottom steel plates of the composite section are gradually decreases during the transfer from the steel stiffening beam to the concrete side. The design of the steel-concrete composite section is reasonably loaded, and the mechanical properties are smoothly transferred.

Behavior of partial-length stiffened and full-length stiffened CFDST columns under axial load

Purpose Concrete-filled double skin tube (CFDST) columns are considered one of the most effective steel-concrete composite sections owing to the higher load carrying capacity as compared to its counterpart concrete-filled tube (CFT) columns. This paper aims to numerically investigate the performance of axially loaded, circular CFDST short columns, with the innovative strengthening technique of providing stiffeners in outer tubes. Circular steel hollow sections have been adopted for inner as well as outer tubes, while varying the length of rectangular steel stiffeners, fixed inside the outer tubes only, to check the effect of stiffeners in partially and full-length stiffened CFDST columns. Design/methodology/approach The behaviour of these CFDST columns is investigated numerically by using a verified finite element analysis (FEA) model from the ABAQUS. The behaviour of 20-unstiffened, 80-partially stiffened and 20-full-length stiffened CFDST columns is studied, while varying the strength of steel (fyo = 250–750 MPa) and concrete (30–90 MPa). Findings The FEA results are verified by comparing them with the previous test results. FEA study has exhibited that, there is a 7%–25% and 39%–49% increase in peak-loads in partially stiffened and full-length stiffened CFDST columns, respectively, compared to unstiffened CFDST columns. Originality/value Enhanced strength has been observed in partially stiffened and full-length stiffened CFDST columns as compared to unstiffened CFDST columns. Also, a significant effect of strength of concrete has not been observed as compared to the strength of steel.

Study on Composite Column Under Monotonic and Cyclic Loading

Nowadays, composite beams and columns were used as structural members for their higher strength and rigidity for load-carrying structures. Generally, the concrete-encased composite column has a compound section formed by the steel section and the surrounding concrete will be made by a composite. Based on the studies of steel encased concrete sections based on experimental and computational analysis over static and dynamic load cases shows advantages over the conventionally use structural steel or reinforced concrete in terms of ductility and shear resistance. The structure can experience static loads as well as fatigue loads in some situations. So the behavior of structural elements under differential loading should be obtained to design them effectively. A similar shape of the column section plays a key role in resisting lateral buckling under axial compression. This paper compares the behaviour of steel concrete composite sections by varying the shape and size for both concrete infilled and encased conditions based on the earlier research works.

Experimental investigation of headed studs in steel-ultra-high performance concrete (UHPC) composite sections

Featuring high compressive and tensile strengths, ultra-high performance concrete (UHPC) is an efficient and durable alternative for conventional concrete in steel–concrete composite sections. However, few experimental studies to date have involved large diameter (≥ 25 mm) headed studs, UHPC with compressive strengths larger than 130 MPa, and relatively low strength but cost-effective UHPC. This study investigates the shear performance of steel headed studs embedded in UHPC through pushout tests with 24 specimens. Specimens included headed studs with diameters of 16 mm, 19 mm, 22 mm, and 25 mm, and either UHPC with compressive strength of 152.5 MPa or a cost-effective UHPC with a strength of 85.7 MPa (named as HPC hereafter). The results showed that smaller-diameter specimens (16 or 19 mm) failed with stud shank fracture, while the larger-diameter specimens (22 or 25 mm) failed at welding lines. Compared to HPC, UHPC did not notably increase the performance of headed shear strength. The load response consisted of a linear stage, a softening stage, and a post-peak stage lasting up to a slip of 10 mm or greater, with high variability in post-peak response among specimens with identical parameters. A global database of 120 push-out test specimens from this study and references was established, covering concrete strengths from 23.5 MPa to 152 MPa. The formulae given by AASHTO LRFD Bridge Design Specification, Eurocode-4, and Chinese code GB50017-2003 overestimated the shear capacity of headed studs by 52 %, 5 % and 53 %, respectively. The equation for the slip modulus slightly overestimated the slip modulus of headed studs. In conclusion, this study broadened the ranges of concrete strength and diameter of headed shear studs, and revealed that the existing equations of predicting shear capacity and slip modulus need improvement.

Compounding effect between influences of fine and coarse recycled aggregates on non-uniform shrinkage behavior of steel-concrete composite slab section

The steel-recycled aggregate concrete (RAC) composite slab is a practical structural member for applying RAC with the fine recycled aggregate (FRA). Despite its advantages, the non-uniform shrinkage (NUS) of composite slabs makes its long-term behaviour the critical factor controlling its design. The use of recycled aggregates would further enlarge the influence of the NUS, while no study has focused on the influence of FRA. Therefore, this paper aims to investigate the influence of FRA on the RAC NUS with different coarse recycled aggregate (CRA) contents. Fifteen RAC slab specimens were fabricated to monitor the shrinkage strain development, considering the replacement ratios of CRA and FRA (rCRA and rFRA), slab thickness, and moisture-transferring boundary conditions. Experimental results showed that 1) the FRA significantly increased both the shrinkage strain value and its gradient through slab thickness, 2) the FRA and CRA had a significant compounding effect (i.e. the influence of FRA varied with rCRA) on the NUS of RAC, and the compounding effect varied with slab thickness. The test results were used to develop a model for the NUS of RAC made with both FRA and CRA. The predicted results well matched the test data from the literature and this study. Finally, a parametric analysis was conducted based on the proposed model.

Feasibility Analysis of Post-Tensioned Beam for Industrial Building: A Review

Abstract: In recent years, due to corrosion and the constant demand for increased traffic flow, there is an eagerly need for an efficient system that can be used to repair or strengthen bridges and structures with steel-concrete composite sections. There have been so many strengthening techniques used to prevent such serious structural problems. One of these most useful techniques, which has successfully proven effective in repairing and strengthening structural members, is to use the externally post-tensioned tendons technique. The various study has also provided a recently completed experimental program on scaled bridge composite steel and concrete beams strengthened with external post-tensioning tendons to explore the fundamental cyclic loading behavior. This article summarizes the design of Post-Tensioned Beam for industrial building and a comparative study between PT Beam and RCC Beam based on a literature survey. We are analyzing such structure in our research having a large span. Manual design of PT Beam for three different span lengths without any intermediate supports and manual design of RCC Beam. We are doing a comparative study of PT Beam and RCC Beam based on the results. This report is based on a study of PT Beam that will aid future research and advances in the construction industry. Keywords: Post-Tensioning Beam, RCC Beam, Industrial Building

State of the Art Report on Steel-Concrete Composite Columns Infilled with Self Compacting Concrete

This paper aims at presenting an extensive critical review of the steel-concrete composite column section infilled with Self Compacting Concrete (SCC). Modern construction widely uses Concrete filled Steel Tubes (CFST) a composite section that enhances the structural capacity of the section and improved stiffness. This paper outlines the research work carried out on the structural behaviour of composite columns with SCC infills of different grades subjected to various loadings and analyzed experimentally and numerically and summarized in the tabular form. In addition, design code formulae for predicting the ultimate load carrying behaviour of the CFST section also highlighted in this paper. Keywords: Composite columns, CFST, Self-compacting concrete, CCR, Slenderness ratio, Bond strength.

Discrete optimisation of steel-concrete composite sections in simple girder bridges

In this study, the optimisation design problem of steel-concrete composite sections in simple girder bridges is developed. Design variables including the thickness of the desk and the dimensions of the girder section are discrete variables to reflect the realistic design works. The total cost of the desk and the steel girder is the objective function that is minimised. The design requirements of the geometry, load-carrying capacity, and deformation provided in the TCVN 11823:2017 standard are used as the optimisation constraints. The above discrete optimisation is solved by using the Harmony Search (HS) algorithm. A 42(m) simple girder is studied. The numerical results show that the optimal designs save about 15% compared to using the conventional design method. It can be concluded that applying the optimisation in the design of steel-concrete composite beams brings high efficiency and it is easily applied in practice.

Influence of residual stress models prescribed in design codes for steel I-section behavior

Non-uniform cooling of steel cross-sections during the manufacturing process generates a state of residual stresses in the cross-section. Design codes describe the distribution of these stresses in different ways. This work aims to numerically investigate the influence of these models on the behavior of bare steel and steel-concrete composite sections by the curves: flexural stiffness-bending moment, moment-curvature and yield curves (initial and full yield). These procedures are important for the study of the simplified curves used in some methodologies of the refined plastic hinge method (RPHM) analysis. The study will use the strain compatibility method (SCM), where, if the axial strain of the cross-section point is known, the section stiffness is obtained using the tangential Young's modulus derived from the materials constitutive relationship. A fiber discretization algorithm is applied and the residual stresses are explicitly inserted into the fibers automatically. The methodology was calibrated using the moment-curvature relationship and the flexural stiffness-bending moment curve. These results were numerically stable and good convergence with literature data was obtained. In general, the residual stress model of the American standard (AISC, 2016) defines a larger elastic region within the interaction diagrams then European model (CEN, 2005). The results obtained showed that the initial yield curves for steel I-sections under minor axis bending require revision for application to RPHM, mainly due to the loss of symmetry in relation to the M axis in the normal force-bending moment (NM) interaction diagram.

Numerical investigation of steel-concrete composite beams using flexible shear connectors

<abstract> <p>This paper focuses on the investigation of the flexural behaviour of steel-concrete composite beams through non-linear finite element analysis. Both geometries, as well as material non-linearity, are considered. Steel-concrete composite beams are typically made consisting of a hot-rolled I-section steel beam and a concrete slab that is connected monolithically by using a shear connector. A shear connector is one of the key elements for developing the composite action used in steel-concrete composite structures. This paper deals with the flexible shear connectors such as studs and channels designed as per the Indian standards 11384. Initially, the FE models are validated by making comparisons with the experimental test results obtained by previous researchers, as available in the literature. In the present study, thirty three-dimensional simply supported composite beams are created and analysed using finite element commercial software package ANSYS15 workbench version subjected to two-point loads. The degree of shear connection, the strength of steel section and the geometry of stud and channel connectors are the primary parameters considered for the present research work, and the results are compared. The overall flexural response is provided, including failure modes, load-central deformation behaviour, and interface slip, as well as the effects of yield strength of steel, the geometry of the stud and channel shear connector along with the degree of shear interaction, are evaluated. The results show that the degree of interaction, the geometry of shear connectors and steel yield strength have significant influence. Subjected to flexure, steel-concrete composite beam section with channel connector is less evaluated so far; therefore, in the present research work, channel shear connector is taken into account to evaluate the flexural behaviour with the consideration of varying grades of steel section along with the degree of interaction and to compare the results with a different section of shear connectors.</p> </abstract>

Utilization of industrial waste materials in concrete-filled steel tubular columns

The idea of this particular study is to utilize industrial waste materials in an effective manner so as to give strength to steel tubular columns. Composite construction using steel - concrete has emerged as one of the fastest methods of construction in India. The inherent advantage of the steel-concrete composite section lies in that the two principal elements - the steel and the concrete are normally used in a manner so that full potential of both may be realized and the best utilization of their respective properties can be made. In this paper, an attempt was made with steel tubular columns in-filled with plain concrete, partial replacement of fine aggregate by fly ash & quarry dust and coarse aggregate by rubber, slag from the steel industry, granite and construction & demolition (C&D) debris concrete. The column specimens are to be tested under axial compression to investigate the effects of industrial waste materials. The effects of the steel tube and the strength of concrete are examined. 24 specimens were tested with the strength of concrete as 20 MPa and D/t ratio 25.40. The columns were 114.3 mm in diameter and 4.5 mm in thickness are 300, 600 & 900 mm in length. Strength characteristics and failure modes are to be discussed. The test results are to be compared with the values predicted by Eurocode 4, Australian Standards and American Codes and new theoretical models will be suggested for the design. From the test results, it was observed that the load-carrying capacity of steel tubular columns in-filled with various industrial waste materials concrete is greater than the conventional concrete. Hence this research would give a solution for effective utilization of industrial waste materials such as rubber, granite, C&D debris, steel slag, fly ash and quarry dust in concrete.

INVESTIGATION OF THE EXPERIMENTAL AND NUMERICAL FLEXURAL BEHAVIOR OF INNOVATIVE TOTALLY ENCASED COMPOSITE BEAMS

Composite steel-concrete beams have been widely used in long span construction and high rise buildings due to their favorable behavior in terms of high strength, stiffness, and ductility. In this research, the flexural behavior of an innovative steel-concrete composite section is investigated experimentally and verified numerically using ABAQUS software. The studied section is composed of steel tubular specimen or steel hollow pipe totally encased in concrete in the absence of any flexural or shear reinforcement. Instead, steel mesh wraps are used around the tubular steel specimen to provide sufficient steel-concrete bond. All of the studied beams have the same 3m length and T-section dimensions to provide adequate comparison of results. The influence of using different percentages of steel mesh wraps around the steel specimen and the structural steel shape effect on the failure mode and ultimate flexural capacity were investigated. It was found that the ABAQUS model has provided excellent simulation of the flexural response of the studied beams with acceptable difference in results as compared to those obtained from experimental testing. Besides, the presence of steel mesh wraps at highly compressive damaged locations have prevented concrete spalling and crushing in these zones by ensuring sufficient steel-concrete bond.

Seismic Performance of a New Type Steel-Concrete Composite Shear Wall

Using steel-concrete composite section is an efficient method for improving the behaviour of shear wall under seismic action. In consideration of the complex configuration of traditional composite shear wall and the time-consuming constructing process, based on the existing research, partially encased composite section was introduced into shear wall system. The partially encased composite shear wall (PECSW) is composed of a steel bone, some horizontal links and a group of concrete columns. The steel bone is a steel web, welded with vertical ribs and flanges in both side at certain interval. The horizontal links connect the flanges (or vertical ribs) and vertical ribs. Concrete is poured on both sides of steel web, between flanges (or vertical ribs) and vertical ribs, formulating several independent long concrete columns. The PECSW can be bulk prefabricated in the factory and transported to the site to install. Because of no vertical rebar in PECSWs, the PECSW structure, which consists of PECSWs and other precast concrete structural elements, can be assembled quickly. This paper reports an experimental study on the seismic behaviour of the PECSW under cyclic lateral loading. Two full-scale single-bay, single-story specimens were constructed. The bearing capacity, energy consumption, stiffness and other performance data had been discussed based on the results of experiment. To explore the possibility of simplifying configuration of PECSW, the web of one specimen was welded with stud shear connectors on both side while the web of another specimen wasn’t. The test results show that the PEC shear wall has a good seismic behaviour. Both specimens followed bending failure mode. The concrete columns offered the vertical bearing capacity as well as the flexural bearing capacity. The concrete and the horizontal links between flanges and ribs provided effective support against local buckling of the flanges, once broken occurred between the links and the flanges, the flanges buckled severely, and the bearing capacity of PECSW fell accordingly. The initial stiffness, yield drift, peak point bearing capacity, accumulated energy dissipation of the PECSW specimens with and without stud shear connectors was basically identical. Then, parametric studies were conducted through numerical simulation so that the contribution of links and the stud shear connectors can be evaluated. According to the research above, the concrete part in the PECSW can postpone local buckling of steel sheet. The horizontal links in the PECSW support interaction between steel and concrete, provide concrete anchorage to steel bone. In general, the PECSW has commendable seismic behaviours and deserve further study.

Behavior of CSC-Type Shear Connectors under Pry-Out Shear Test: Analytical Study

The use of cold-formed steel (CFS) shapes in steel-concrete composite sections has increased over the past 20 years in the construction industry worldwide. This system has constructive advantages such as high load-bearing capacity, high stiffness and ductility, ease of transportation and assembly, and full usage of the capacity of the materials. Additionally, CFS sections are considered a sustainable alternative in construction.The capacity of the system depends on the effectiveness of shear connectors during the transfer of stress between materials. Currently, the push-out experimental test follows a standardized procedure to evaluate the capacity of shear connectors in composite sections, but CFS shapes have demonstrated premature failures by local buckling, thus questioning the applicability of the experimental test for such configurations.In this research, the capacity of the proposed confined shear connectors (CSC) is evaluated in composite systems, through the alternative pry-out test methodology. From numerical models, the effects of the steel shape thickness, the thickness of concrete slabs, the compressive strength of concrete and the separation between connectors in composite systems are studied. The analysis concluded that, under this test methodology, the separation between connectors does not represent statistically significant changes in the final capacity of the composite system.

Cyclic loading behavior on strengthened composite beams using external post-tensioning tendons (experimental study)

In recent years, due to corrosion and the constant demand for increased traffic flow, it emerged that there is a need for an efficient system that can be used to repair and / or strengthen bridges and structures with steel–concrete composite section. There have been many strengthening techniques used to prevent such serious structural problems. One of these techniques, which has proven effective in repairing and strengthening structural members, is to use externally post-tensioned tendons. This study provides a recently completed experimental program on scaled bridge composite steel–concrete beams strengthened with external post-tensioning tendons to investigate the fundamental cyclic loading behavior. In addition to studying the effect of the strengthening system, there was another major factor under study which was the degree of shear connection. The study mainly relied on testing the beams under the influence of cyclic loads in addition to changing the degree of shear contact. Reducing the degree of shear connection simulates a form of composite action loss of composite beams due to cyclic loads. The study results provides modes of failure, characteristic points, load–deflection curves, slip between steel beam top flange and the concrete flange, the shear connector strains, and the concrete and steel beam bottom flanges strains. Based on the experimental results, adding external post-tensioning enhanced the overall performance of the composite beams under cyclic loading by significantly reducing strains of the shear studs, the concrete flange, and the steel I-beam at all loading stages. The strengthened specimens experienced an increase in the ultimate capacity and residual stiffness comparable to non-strengthened specimens, attributable to significant loss of composite action between concrete flange and steel beam through cyclic load test.

Alternative Fastening Mechanism for Shear Connectors with Cold-Formed Steel Shapes Involved in Composite Sections

Over the past few decades, the use of steel-concrete composite sections has increased globally, in order to take advantage of compression strength in concrete and tensile strength in steel, ensuring its fastening through stress transfer elements denominated shear connectors. The main connection systems endorsed by the current design codes are used by applying welding as fastening mechanism to fix connectors. However, this thermal procedure produces concentration of residual stresses during cooling process, and risk of perforation in Cold-Formed Steel sections (CFS), affecting the behavior efficiency of the composite sections. In this research, self-drilling screws are proposed as an alternative mechanical system for connectors fastening. An experimental program was carried out to validate capacity and performance of the system, through Full-Scale Beam Tests. According to results, self-drilling screws are a viable alternative to be used as fastening mechanism in shear connectors for CFS and concrete composite sections. Composite system achieved to develop full capacity, even in inelastic range, without disconnection between materials. Self-drilling screws remained fixed on steel shapes without mechanical damage, allowing greater deformations, than structural service conditions.

Axial slenderness limits for duplex and lean duplex stainless steel-concrete composite columns

The present study is focused on the local stability of concrete-filled and partially-encased stainless steel sections, fabricated from duplex and lean duplex plates, under axial compression. A total of 34 specimens with box, circular, and I-shaped sections are investigated. Geometrical imperfections of the fabricated stainless steel specimens are measured prior to testing. Following the experiments, a comprehensive parametric study is conducted using finite element method. Results of the experiments as well as the parametric study are then synthesised to recommend axial slenderness limits for the investigated section types. The recommended limits are compared with those stipulated by current design specifications for carbon steel-concrete composite sections. The findings are also compared with the previous data available in the literature for austenitic composite sections and the similarities and differences are highlighted and discussed. The experimental and numerical results are further investigated to calibrate effective width relations to exploit the post-local buckling reserve strength of the studied sections. To facilitate the comparison of the findings with current codified requirements and other studies, the recommendations are presented in three notations used typically by the Australian, American, and European standards.