This document summarizes research analyzing test data on 1817 composite concrete-filled steel columns. The test results are compared to calculations according to Eurocode 4 design methods. Several key findings are presented:
1) Test results for circular composite columns generally corresponded well with Eurocode 4 calculations. Test capacities of rectangular columns agreed with calculations when concrete strength was below 75 MPa.
2) Preloading composite members did not influence load-bearing capacity.
3) Analysis of stress distributions, preloading effects, and stress-strain curves was also examined.
4) Test/calculation ratios from the data indicate Eurocode 4 methods are generally conservative, with average ratios above 1.0 for different column types.
Concrete filled steel tubes subjected to axial compressioneSAT Journals
Abstract Concrete-filled steel tubular columns have excellent earth-quake resistant properties such as high strength and ductility and large energy absorption capacity. For concrete-filled steel tubes (CFST), local buckling commonly observed in bare steel columns is effectively prevented, giving a higher capacity. However if the concrete core and the steel tube are loaded simultaneously the steel tube expands more than the concrete core under moderate loads since Poisson’s ratio is higher for the steel section. The objective of this paper is To evaluate the accuracy of codal design approach by comparing experimental results with the analytical results obtained using EC4, ACI-318 and AISC-LRFD, for prediction of load carrying capacity of CFST columns under axial compression. Based on this the experimental programme is conducted on concrete filled steel tubes of length 300mm, thickness 1 to 3mm for circular, square and rectangular cross section with three different grades of concrete.200 T capacity Compression testing machine is used for experimental investigation.. The experimental results are compared with analytical results obtained by stated code of practices. From this it is concluded that EC4 gives conservative results. From which it is observed that EC4 gives conservative results with experimental results and it is concluded that EC4 provisions may be used for further analytical study to develop an expression to predict the section capacity CFST columns. As the grade of concrete increases the load carrying capacity is also increases. This paper presents the details of study carried out and the conclusions arrived. Keywords: CFST, high strength, local buckling, analytical, ACI-318, EC4, AISC-LRFD.
This document is a seminar report submitted by Alok B. Rathod for the degree of Master of Technology in Structural Engineering at Bhartiya Vidya Bhavan’s Sardar Patel College of Engineering in Mumbai, India. The report reviews the development of concrete-filled steel tubular structures, including their material properties and behavior under various loads. It summarizes research on their static, dynamic, and fire performance, as well as construction and durability. Design criteria from different codes are examined and examples of CFST applications in buildings, bridges, and other structures are provided.
This document provides an introduction and literature review on concrete filled steel tube (CFST) columns. Some key points:
1) CFST columns utilize the advantages of both steel and concrete by using a steel hollow section filled with concrete. They are widely used in building construction.
2) Previous research has shown CFST columns have improved structural performance due to confinement of the concrete core by the steel tube. They also have construction advantages due to their simple erection sequence.
3) The literature review covers the behavior of CFST under different load cases like axial, bending, and combined loads. It also discusses design concepts, analytical methods, and codes/standards for CFST columns.
The document summarizes a numerical study on the behavior of concrete-filled steel tube columns under axial loads. A finite element model was developed using ABAQUS to simulate the composite action between the steel tube and concrete core. The model considers the nonlinear stress-strain behavior of confined concrete and elastic-plastic behavior of steel. The results of the model were validated by comparing ultimate loads to experimental data, with a maximum difference of 5-10%. Analytical calculations from codes like ACI and Eurocode were also compared to the experimental and numerical ultimate loads.
This document summarizes analytical studies on concrete filled steel tubes. A finite element model of a rectangular concrete filled steel tube short column was created using ANSYS software. The model was validated against experimental data. Both eigenvalue and nonlinear buckling analyses were performed to determine the ultimate axial load capacity of the column. The eigenvalue analysis provides the theoretical buckling strength, while the nonlinear analysis is more accurate as it considers factors like imperfections and plastic behavior. The results from the ANSYS model were used to develop an approximate formula for calculating the ultimate load of rectangular concrete filled steel tube short columns based on material properties.
This document provides an overview of concrete filled steel tubes (CFT). It discusses the history and components of CFT, how steel tubes confine concrete and improve its properties. Comparisons are made between CFT and steel or reinforced concrete columns. Applications discussed include tall buildings, bridges and the Canton Tower. Advantages of CFT include increased strength and ductility over steel or concrete alone. Limitations relate to limited knowledge of CFT behavior and determining combined properties.
CONCRETE FILLED STEEL TUBULAR COLUMNS USING GS SHEETAL AMIN AZIZ
1) The document presents the findings of an experimental investigation on concrete filled steel tubular columns using galvanized steel sheet strengthened with self-compacting concrete.
2) The investigation found that confined columns exhibited less axial deformation than unconfined columns under the same loads and failed initially at the top and bottom before failing in the middle.
3) It was concluded that confined columns provided higher strength than unconfined columns and failed due to shear stresses, while further research is needed on casting methods and numerical modeling to better understand column behavior.
Concrete filled steel tubes subjected to axial compressioneSAT Journals
Abstract Concrete-filled steel tubular columns have excellent earth-quake resistant properties such as high strength and ductility and large energy absorption capacity. For concrete-filled steel tubes (CFST), local buckling commonly observed in bare steel columns is effectively prevented, giving a higher capacity. However if the concrete core and the steel tube are loaded simultaneously the steel tube expands more than the concrete core under moderate loads since Poisson’s ratio is higher for the steel section. The objective of this paper is To evaluate the accuracy of codal design approach by comparing experimental results with the analytical results obtained using EC4, ACI-318 and AISC-LRFD, for prediction of load carrying capacity of CFST columns under axial compression. Based on this the experimental programme is conducted on concrete filled steel tubes of length 300mm, thickness 1 to 3mm for circular, square and rectangular cross section with three different grades of concrete.200 T capacity Compression testing machine is used for experimental investigation.. The experimental results are compared with analytical results obtained by stated code of practices. From this it is concluded that EC4 gives conservative results. From which it is observed that EC4 gives conservative results with experimental results and it is concluded that EC4 provisions may be used for further analytical study to develop an expression to predict the section capacity CFST columns. As the grade of concrete increases the load carrying capacity is also increases. This paper presents the details of study carried out and the conclusions arrived. Keywords: CFST, high strength, local buckling, analytical, ACI-318, EC4, AISC-LRFD.
This document is a seminar report submitted by Alok B. Rathod for the degree of Master of Technology in Structural Engineering at Bhartiya Vidya Bhavan’s Sardar Patel College of Engineering in Mumbai, India. The report reviews the development of concrete-filled steel tubular structures, including their material properties and behavior under various loads. It summarizes research on their static, dynamic, and fire performance, as well as construction and durability. Design criteria from different codes are examined and examples of CFST applications in buildings, bridges, and other structures are provided.
This document provides an introduction and literature review on concrete filled steel tube (CFST) columns. Some key points:
1) CFST columns utilize the advantages of both steel and concrete by using a steel hollow section filled with concrete. They are widely used in building construction.
2) Previous research has shown CFST columns have improved structural performance due to confinement of the concrete core by the steel tube. They also have construction advantages due to their simple erection sequence.
3) The literature review covers the behavior of CFST under different load cases like axial, bending, and combined loads. It also discusses design concepts, analytical methods, and codes/standards for CFST columns.
The document summarizes a numerical study on the behavior of concrete-filled steel tube columns under axial loads. A finite element model was developed using ABAQUS to simulate the composite action between the steel tube and concrete core. The model considers the nonlinear stress-strain behavior of confined concrete and elastic-plastic behavior of steel. The results of the model were validated by comparing ultimate loads to experimental data, with a maximum difference of 5-10%. Analytical calculations from codes like ACI and Eurocode were also compared to the experimental and numerical ultimate loads.
This document summarizes analytical studies on concrete filled steel tubes. A finite element model of a rectangular concrete filled steel tube short column was created using ANSYS software. The model was validated against experimental data. Both eigenvalue and nonlinear buckling analyses were performed to determine the ultimate axial load capacity of the column. The eigenvalue analysis provides the theoretical buckling strength, while the nonlinear analysis is more accurate as it considers factors like imperfections and plastic behavior. The results from the ANSYS model were used to develop an approximate formula for calculating the ultimate load of rectangular concrete filled steel tube short columns based on material properties.
This document provides an overview of concrete filled steel tubes (CFT). It discusses the history and components of CFT, how steel tubes confine concrete and improve its properties. Comparisons are made between CFT and steel or reinforced concrete columns. Applications discussed include tall buildings, bridges and the Canton Tower. Advantages of CFT include increased strength and ductility over steel or concrete alone. Limitations relate to limited knowledge of CFT behavior and determining combined properties.
CONCRETE FILLED STEEL TUBULAR COLUMNS USING GS SHEETAL AMIN AZIZ
1) The document presents the findings of an experimental investigation on concrete filled steel tubular columns using galvanized steel sheet strengthened with self-compacting concrete.
2) The investigation found that confined columns exhibited less axial deformation than unconfined columns under the same loads and failed initially at the top and bottom before failing in the middle.
3) It was concluded that confined columns provided higher strength than unconfined columns and failed due to shear stresses, while further research is needed on casting methods and numerical modeling to better understand column behavior.
This document provides an introduction and overview of the contents of a book on the behavior and modeling of concrete-filled steel tubular (CFST) columns and beam-columns. The document outlines 6 chapters that will be included in the book, covering topics such as: the fiber element method for modeling CFST short columns; analysis of uniaxially loaded CFST slender beam-columns; modeling of biaxially loaded CFST beam-columns; modeling the effects of preloads on CFST columns; and modeling the cyclic behavior of CFST slender beam-columns. The document acknowledges contributions from various researchers and expresses thanks for their support.
The document discusses concrete filled steel tube (CFST) columns under axial compressive loads. It summarizes that CFST columns have higher load capacity than hollow steel tubes due to the composite action between steel and concrete. Experimental tests were conducted on circular and square CFST columns with varying concrete grades and heights. The results showed that square CFST columns had higher load capacity than circular columns. Ultimate load also increased with higher concrete grade. Failure modes included local and overall buckling. CFST columns provide advantages like increased strength, reduced construction costs, and improved fire resistance compared to reinforced concrete columns.
Parametric Study of Square Concrete Filled Steel Tube Columns Subjected To Co...IJERA Editor
The Concrete Filled Steel Tube (CFST) member has many advantages compared with the conventional concrete structural member. This study presents on the behaviour of concrete-filled steel tube (CFST) columns under axial load by changing parameters. The parameters are thickness of steel tube, Grade of concrete and length of column. The study was conducted using ANSYS 13 finite element software. All the columns are 60 X 60 mm in size. The thickness of the tube is taken as 2, 3, 4, 5 and 6 mm for thickness variation. The grades of concrete infill are M25, M30, M40, M50, M60 and M70 used for grade variation. Lengths of columns are taken as 900, 1200, 1500, 1800, 2100, and 2400 mm for length variation. Buckling load is compared with Euro code 4 (1994).
Experimental investigation on triple blended scc filled steel tubes with and ...eSAT Journals
Abstract
Concrete filled steel tubular columns are gaining its popularity in engineering practice. However, local buckling is the main criteria which effects on strength and ductility for the composite columns. In order to enhance their overall performance, one of the most effective measures is to provide stiffeners for the steel tubes. In the present research, experimental studies have been devoted to investigating the behavior of self-compacting Concrete Filled Steel Tube (CFST) stub columns strengthened by single or double stiffeners. A total of 36 stub columns specimen under monotonic compression load were tested in order to discover the best configuration of column system where (specimen having zero stiffeners, single stiffener, double stiffeners) each for hollow steel and with SCC in-filled are tested for 7 days, 28 days and 56 days strength with circular cross-sections of dimensions 300mm height x100mm diameter x 2mm thickness. The experimental results indicated that the use of Stiffeners strengthen the CFST has a significant effect on the overall behavior of CFST such as enhancement on its strength and ductility. Also the Stiffeners confinement delays local buckling of steel tube, prevents a sudden strength reduction caused by the local buckling of the steel tube, and increases lateral confinement of the concrete core. It is found that the best configuration of Stiffeners in the Steel tubes is providing it in transverse direction with single and double stiffeners at a height of h/2 and h/3 respectively.
This is my M.Tech Project presentation. The project was carried out at R.V College of Engineering and B.M.S College of Engineering, Bangalore. In this project, the axial load carrying capacity of CFST Columns was studied and the experimental results were compared with Eurocode-4 and AISC-LRFD-2005. The flexural capacity of CFST frames was also carried out.
The document presents a finite element analysis of concrete filled steel tube (CFT) beams subjected to flexure. A numerical model was developed using ANSYS to predict the flexural behavior and moment capacity of circular and rectangular CFT beams. The model considered the material properties of steel and concrete, and incorporated the interaction between concrete and steel. Results of the numerical analysis for moment capacity were compared to experimental data. For circular CFT beams, the predicted capacities matched well with experimental values. The analysis showed rectangular CFTs can provide good confinement of the concrete core.
Dynamic behavior of composite filled circular steel tubes with light weight c...eSAT Journals
Abstract An experimental and analytical investigation of concrete-filled steel tubular (CFST) columns is presented. composite circular steel tubes- with light weight concrete as infill for three different grades of light weight concrete say M20,M30 and M40 are tested for ultimate load capacity and axial shortening , under cyclic loading. steel tubes are compared for different lengths, cross sections and constant thickness. From this research study it is expected that ,regression models which were developed with minimum number of experiments based on taguchi’s method predicted the axial load carrying capacity very well and reasonably well at ultimate point. Cross sectional area of steel tube has most significant effect on ultimate load carrying capacity also it is observed that, as length of steel tube increased- load carrying capacity decreased. Keywords: Composite Columns, Hallow Steel Tubes, Light Weight Concrete Filled Steel Tubes, light weight concrete
This study used finite element analysis to model concrete-filled steel tube beams that were partially wrapped with carbon fiber reinforced polymer (CFRP) sheets. The objectives were to investigate how CFRP wrapping length and number of layers affected structural behavior. Models of square and circular cross-section beams were created and verified. The analysis found that beams wrapped along 50% of their length saw reduced capacity with additional CFRP layers due to delamination failures. Beams wrapped along 75-100% saw increased capacity with more CFRP layers up to their ultimate strengths. Circular beams saw better strength improvements than square beams when wrapped with 1-3 CFRP layers.
The document summarizes a study on the effect of shape of cross-section on the performance of concrete filled steel fluted columns. Twenty-six concrete filled steel fluted columns with different cross-sectional shapes (triangular and rectangular flutes) and L/D ratios were tested. It was found that:
1) Rectangular fluted columns performed better than triangular fluted columns, supporting more load by 1-10%.
2) The moment of inertia was increased by 17-40% for rectangular fluted columns and 9-23% for triangular fluted columns, compared to plain columns.
3) The development length (width) of the fluted columns was 14-34% greater than plain
This document summarizes an experimental study on the behavior of built-up steel-concrete composite columns with angle sections under axial and eccentric loading. The study included testing composite columns with conventional concrete, fiber reinforced concrete, and additional reinforcement. Load-deflection behavior, moment-curvature relationships, and load-moment interaction diagrams are presented and discussed. Key findings include the concrete carrying most of the load and failing in compression before steel yields, and fiber reinforced and reinforced specimens exhibiting higher load capacities than conventional concrete specimens.
IRJET- Effects of Different Parameters on Inelastic Buckling Behavior of ...IRJET Journal
This document discusses a study that analyzed the buckling behavior of composite concrete-filled steel tube columns with different parameters. The study used finite element analysis to model composite columns with double I-beam cross sections. It investigated the effects of eccentric loading, slenderness ratio, and distance between steel profiles on buckling capacity. The results showed that filling steel sections with concrete delays steel yielding and increases column capacity. Greater concrete surface area and lower slenderness ratio also led to higher strength due to increased confinement effects.
IRJET- A Study on Concrete Filled Steel Tubular Column Steel Beam Connect...IRJET Journal
This document summarizes a study on the behavior of steel beam to concrete filled steel tubular column connections using different types of concrete. Specifically, it examines connections using light weight concrete and normal concrete with an external diaphragm. Two specimens of each concrete type were tested under static loading. The results showed panel zone deformation in the beam-column joints for both light weight and normal concrete. However, light weight concrete connections performed better in terms of seismic performance and energy dissipation compared to normal concrete connections. The aim of the study was to develop a more economical concrete filled steel tubular structure system by utilizing lighter concrete materials.
The document provides an overview of corrosion of steel in concrete. It discusses how steel is usually protected from corrosion by the alkaline environment of concrete but can corrode due to carbonation or chloride attack breaking down the protective layer. The corrosion process involves steel dissolving at the anode and oxygen being consumed at the cathode. This leads to a volume increase and the formation of rust, causing cracking and spalling of concrete. It also describes "black rust" that can occur in low-oxygen conditions without visible damage. The document aims to explain the basics of corrosion mechanisms to help understand investigation and repair techniques.
Advanced Design of Composite Steel-Concrete Structural elementIJERA Editor
Composite framing system consisting of steel beams acting interactively with metal deck-concrete slab and concrete encased composite columns, has been as a viable alternative to the conventional steel or reinforced concrete system in the high-rise construction. However, in Indian context, it is comparatively new and no appropriate design codes are available for the same. Complications in the analysis and design of composite structures have led numerous researchers to develop simplified methods so as to eliminate a number of large scale tests needed for the design. In the present work, a simplified method of composite slabs, beams and columns design is used and software is developed with pre- and post- processing facilities in VB.NET. All principal design checks are incorporated in the software. The full and partial shear connection and the requirement for transverse reinforcement are also considered. To facilitate direct selection of steel section, a database is prepared and is available at the back end with the properties of all standard steel sections. Screen shots are included in the paper to illustrate the method employed for selecting the appropriate section and shear connectors and thus to verify the design adequacy.
The Structural Behaviour of Concrete Filled Steel Tubular columnsIRJET Journal
This document describes a study comparing the structural behavior of concrete-filled steel tubular columns made with different steel materials through numerical analysis and experimental testing. Six column specimens were tested - two each made with stainless steel, mild steel, and cold-formed steel tubes. Both short and long columns were analyzed. The numerical analysis found that stainless steel columns had the highest load-carrying capacity. The experimental results supported this, with stainless steel columns outperforming the other materials. There was good agreement between the numerical and experimental load values, with errors generally below 5%. The study concluded that stainless steel provided the best performance for concrete-filled steel tubular columns subjected to axial loads.
IRJET- Review on Steel Concrete Composite ColumnIRJET Journal
1. The document reviews research on steel-concrete composite columns, where steel columns are infilled with concrete. Wire mesh is welded inside steel columns to improve bond between steel and concrete.
2. Three composite columns and three reinforced concrete columns of the same size were tested and compared. The composite columns showed better structural behavior than reinforced concrete columns in terms of ultimate strength, ductility, energy absorption capacity, and stiffness.
3. The literature review discussed previous research on composite columns that found infilling concrete inside steel tubes improves tensile strength and load capacity compared to hollow steel tubes. Previous studies also showed that composite columns experienced less damage than steel-only columns under the same loads.
Comparative Analysis between Tube in Tube Structure and Conventional Moment R...IRJET Journal
This document compares the performance of a conventional moment resisting frame structure to a tube-in-tube steel structure through computer modeling and analysis. Five 50-story building models are analyzed: a conventional frame, two tube-in-tube structures with different column spacing, and two tube-in-tube structures with additional X bracing. The analyses indicate that the tube-in-tube structures perform better in resisting lateral loads but have greater displacements. Reducing column spacing and adding bracing in the tube-in-tube models increases their stiffness and decreases displacements and drift, while increasing base shear and accelerations. The tube-in-tube structure with close column spacing and bracing provides the best performance against static and dynamic loads
IRJET- Behaviour of CFST Column Element with & without Shear Studs under ...IRJET Journal
This document summarizes research on the behavior of concrete-filled steel tube (CFST) columns. It discusses how CFST columns offer benefits like strength, ductility and construction efficiency compared to traditional hollow steel tubes or reinforced concrete columns. The paper reviews past research on the load-carrying capacity of CFST columns according to different design codes. It also describes finite element models and experiments that were conducted to analyze the behavior of CFST columns under axial compression loads. In particular, the research presented in the paper compares the performance of CFST column models with and without shear studs in different positions.
IRJET- Study on the Structural Behavior of Concrete Encased Steel Composi...IRJET Journal
This document summarizes a study on the structural behavior of concrete-encased steel composite columns. Theoretical, analytical, and experimental investigations were conducted. The finite element software ANSYS was used for analytical modeling. In experiments, reinforced concrete columns were compared to concrete-encased steel columns with varying steel section orientations. The results showed that concrete-encased steel composite columns exhibited higher load capacity and less axial shortening compared to reinforced concrete columns. The orientation of the encased steel section also affected the structural behavior. In general, the study demonstrated that concrete-encased steel composite columns provide improved structural performance over conventional reinforced concrete columns.
The document compares the design buckling resistance of a steel column according to three different structural design standards: SANS 10162-1:2005/CAN/CSA-S16-01:2005 (South African/Canadian standard), Eurocode 3, and AS 4100:1998/NZS3404:1997 (Australian/New Zealand standard). It finds that while the standards have some similarities in their classification of cross-sections and consideration of effective lengths and imperfections, there are also differences. A worked example calculates the design buckling resistance of a specific steel column according to the South African standard and finds the capacity varies with the slenderness ratio and standard used.
Every industry focus to build and improve the
chimney to create the eco-friend organization as well as to
satisfy the strict environmental board.
IS: 4998 criteria for design of reinforced concrete chimneys
is using working stress method for chimney designing.
There are some limitations of working stress method. Also
the designing is difficult involving lengthy, cumbersome
and iterative computational effort.
So we should recognize this problem and we should use
some time saving techniques like interaction envelopes to
optimize the structural design.
Chimneys with various heights from 65m to 280m are
analyzed and designed by working stress method and limit
state method for collapse and comparison of results are
discussed in this paper. Generation of interaction curves for
hollow circular section is also discussed in this paper.
This document provides an introduction and overview of the contents of a book on the behavior and modeling of concrete-filled steel tubular (CFST) columns and beam-columns. The document outlines 6 chapters that will be included in the book, covering topics such as: the fiber element method for modeling CFST short columns; analysis of uniaxially loaded CFST slender beam-columns; modeling of biaxially loaded CFST beam-columns; modeling the effects of preloads on CFST columns; and modeling the cyclic behavior of CFST slender beam-columns. The document acknowledges contributions from various researchers and expresses thanks for their support.
The document discusses concrete filled steel tube (CFST) columns under axial compressive loads. It summarizes that CFST columns have higher load capacity than hollow steel tubes due to the composite action between steel and concrete. Experimental tests were conducted on circular and square CFST columns with varying concrete grades and heights. The results showed that square CFST columns had higher load capacity than circular columns. Ultimate load also increased with higher concrete grade. Failure modes included local and overall buckling. CFST columns provide advantages like increased strength, reduced construction costs, and improved fire resistance compared to reinforced concrete columns.
Parametric Study of Square Concrete Filled Steel Tube Columns Subjected To Co...IJERA Editor
The Concrete Filled Steel Tube (CFST) member has many advantages compared with the conventional concrete structural member. This study presents on the behaviour of concrete-filled steel tube (CFST) columns under axial load by changing parameters. The parameters are thickness of steel tube, Grade of concrete and length of column. The study was conducted using ANSYS 13 finite element software. All the columns are 60 X 60 mm in size. The thickness of the tube is taken as 2, 3, 4, 5 and 6 mm for thickness variation. The grades of concrete infill are M25, M30, M40, M50, M60 and M70 used for grade variation. Lengths of columns are taken as 900, 1200, 1500, 1800, 2100, and 2400 mm for length variation. Buckling load is compared with Euro code 4 (1994).
Experimental investigation on triple blended scc filled steel tubes with and ...eSAT Journals
Abstract
Concrete filled steel tubular columns are gaining its popularity in engineering practice. However, local buckling is the main criteria which effects on strength and ductility for the composite columns. In order to enhance their overall performance, one of the most effective measures is to provide stiffeners for the steel tubes. In the present research, experimental studies have been devoted to investigating the behavior of self-compacting Concrete Filled Steel Tube (CFST) stub columns strengthened by single or double stiffeners. A total of 36 stub columns specimen under monotonic compression load were tested in order to discover the best configuration of column system where (specimen having zero stiffeners, single stiffener, double stiffeners) each for hollow steel and with SCC in-filled are tested for 7 days, 28 days and 56 days strength with circular cross-sections of dimensions 300mm height x100mm diameter x 2mm thickness. The experimental results indicated that the use of Stiffeners strengthen the CFST has a significant effect on the overall behavior of CFST such as enhancement on its strength and ductility. Also the Stiffeners confinement delays local buckling of steel tube, prevents a sudden strength reduction caused by the local buckling of the steel tube, and increases lateral confinement of the concrete core. It is found that the best configuration of Stiffeners in the Steel tubes is providing it in transverse direction with single and double stiffeners at a height of h/2 and h/3 respectively.
This is my M.Tech Project presentation. The project was carried out at R.V College of Engineering and B.M.S College of Engineering, Bangalore. In this project, the axial load carrying capacity of CFST Columns was studied and the experimental results were compared with Eurocode-4 and AISC-LRFD-2005. The flexural capacity of CFST frames was also carried out.
The document presents a finite element analysis of concrete filled steel tube (CFT) beams subjected to flexure. A numerical model was developed using ANSYS to predict the flexural behavior and moment capacity of circular and rectangular CFT beams. The model considered the material properties of steel and concrete, and incorporated the interaction between concrete and steel. Results of the numerical analysis for moment capacity were compared to experimental data. For circular CFT beams, the predicted capacities matched well with experimental values. The analysis showed rectangular CFTs can provide good confinement of the concrete core.
Dynamic behavior of composite filled circular steel tubes with light weight c...eSAT Journals
Abstract An experimental and analytical investigation of concrete-filled steel tubular (CFST) columns is presented. composite circular steel tubes- with light weight concrete as infill for three different grades of light weight concrete say M20,M30 and M40 are tested for ultimate load capacity and axial shortening , under cyclic loading. steel tubes are compared for different lengths, cross sections and constant thickness. From this research study it is expected that ,regression models which were developed with minimum number of experiments based on taguchi’s method predicted the axial load carrying capacity very well and reasonably well at ultimate point. Cross sectional area of steel tube has most significant effect on ultimate load carrying capacity also it is observed that, as length of steel tube increased- load carrying capacity decreased. Keywords: Composite Columns, Hallow Steel Tubes, Light Weight Concrete Filled Steel Tubes, light weight concrete
This study used finite element analysis to model concrete-filled steel tube beams that were partially wrapped with carbon fiber reinforced polymer (CFRP) sheets. The objectives were to investigate how CFRP wrapping length and number of layers affected structural behavior. Models of square and circular cross-section beams were created and verified. The analysis found that beams wrapped along 50% of their length saw reduced capacity with additional CFRP layers due to delamination failures. Beams wrapped along 75-100% saw increased capacity with more CFRP layers up to their ultimate strengths. Circular beams saw better strength improvements than square beams when wrapped with 1-3 CFRP layers.
The document summarizes a study on the effect of shape of cross-section on the performance of concrete filled steel fluted columns. Twenty-six concrete filled steel fluted columns with different cross-sectional shapes (triangular and rectangular flutes) and L/D ratios were tested. It was found that:
1) Rectangular fluted columns performed better than triangular fluted columns, supporting more load by 1-10%.
2) The moment of inertia was increased by 17-40% for rectangular fluted columns and 9-23% for triangular fluted columns, compared to plain columns.
3) The development length (width) of the fluted columns was 14-34% greater than plain
This document summarizes an experimental study on the behavior of built-up steel-concrete composite columns with angle sections under axial and eccentric loading. The study included testing composite columns with conventional concrete, fiber reinforced concrete, and additional reinforcement. Load-deflection behavior, moment-curvature relationships, and load-moment interaction diagrams are presented and discussed. Key findings include the concrete carrying most of the load and failing in compression before steel yields, and fiber reinforced and reinforced specimens exhibiting higher load capacities than conventional concrete specimens.
IRJET- Effects of Different Parameters on Inelastic Buckling Behavior of ...IRJET Journal
This document discusses a study that analyzed the buckling behavior of composite concrete-filled steel tube columns with different parameters. The study used finite element analysis to model composite columns with double I-beam cross sections. It investigated the effects of eccentric loading, slenderness ratio, and distance between steel profiles on buckling capacity. The results showed that filling steel sections with concrete delays steel yielding and increases column capacity. Greater concrete surface area and lower slenderness ratio also led to higher strength due to increased confinement effects.
IRJET- A Study on Concrete Filled Steel Tubular Column Steel Beam Connect...IRJET Journal
This document summarizes a study on the behavior of steel beam to concrete filled steel tubular column connections using different types of concrete. Specifically, it examines connections using light weight concrete and normal concrete with an external diaphragm. Two specimens of each concrete type were tested under static loading. The results showed panel zone deformation in the beam-column joints for both light weight and normal concrete. However, light weight concrete connections performed better in terms of seismic performance and energy dissipation compared to normal concrete connections. The aim of the study was to develop a more economical concrete filled steel tubular structure system by utilizing lighter concrete materials.
The document provides an overview of corrosion of steel in concrete. It discusses how steel is usually protected from corrosion by the alkaline environment of concrete but can corrode due to carbonation or chloride attack breaking down the protective layer. The corrosion process involves steel dissolving at the anode and oxygen being consumed at the cathode. This leads to a volume increase and the formation of rust, causing cracking and spalling of concrete. It also describes "black rust" that can occur in low-oxygen conditions without visible damage. The document aims to explain the basics of corrosion mechanisms to help understand investigation and repair techniques.
Advanced Design of Composite Steel-Concrete Structural elementIJERA Editor
Composite framing system consisting of steel beams acting interactively with metal deck-concrete slab and concrete encased composite columns, has been as a viable alternative to the conventional steel or reinforced concrete system in the high-rise construction. However, in Indian context, it is comparatively new and no appropriate design codes are available for the same. Complications in the analysis and design of composite structures have led numerous researchers to develop simplified methods so as to eliminate a number of large scale tests needed for the design. In the present work, a simplified method of composite slabs, beams and columns design is used and software is developed with pre- and post- processing facilities in VB.NET. All principal design checks are incorporated in the software. The full and partial shear connection and the requirement for transverse reinforcement are also considered. To facilitate direct selection of steel section, a database is prepared and is available at the back end with the properties of all standard steel sections. Screen shots are included in the paper to illustrate the method employed for selecting the appropriate section and shear connectors and thus to verify the design adequacy.
The Structural Behaviour of Concrete Filled Steel Tubular columnsIRJET Journal
This document describes a study comparing the structural behavior of concrete-filled steel tubular columns made with different steel materials through numerical analysis and experimental testing. Six column specimens were tested - two each made with stainless steel, mild steel, and cold-formed steel tubes. Both short and long columns were analyzed. The numerical analysis found that stainless steel columns had the highest load-carrying capacity. The experimental results supported this, with stainless steel columns outperforming the other materials. There was good agreement between the numerical and experimental load values, with errors generally below 5%. The study concluded that stainless steel provided the best performance for concrete-filled steel tubular columns subjected to axial loads.
IRJET- Review on Steel Concrete Composite ColumnIRJET Journal
1. The document reviews research on steel-concrete composite columns, where steel columns are infilled with concrete. Wire mesh is welded inside steel columns to improve bond between steel and concrete.
2. Three composite columns and three reinforced concrete columns of the same size were tested and compared. The composite columns showed better structural behavior than reinforced concrete columns in terms of ultimate strength, ductility, energy absorption capacity, and stiffness.
3. The literature review discussed previous research on composite columns that found infilling concrete inside steel tubes improves tensile strength and load capacity compared to hollow steel tubes. Previous studies also showed that composite columns experienced less damage than steel-only columns under the same loads.
Comparative Analysis between Tube in Tube Structure and Conventional Moment R...IRJET Journal
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Every industry focus to build and improve the
chimney to create the eco-friend organization as well as to
satisfy the strict environmental board.
IS: 4998 criteria for design of reinforced concrete chimneys
is using working stress method for chimney designing.
There are some limitations of working stress method. Also
the designing is difficult involving lengthy, cumbersome
and iterative computational effort.
So we should recognize this problem and we should use
some time saving techniques like interaction envelopes to
optimize the structural design.
Chimneys with various heights from 65m to 280m are
analyzed and designed by working stress method and limit
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Buckling of slender composite concrete filled steel columns
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Buckling of slender composite concrete‐filled steel
columns
C. Douglas Goode , Artiomas Kuranovas & Audronis Kazimieras Kvedaras
To cite this article: C. Douglas Goode , Artiomas Kuranovas & Audronis Kazimieras Kvedaras
(2010) Buckling of slender composite concrete‐filled steel columns, Journal of Civil Engineering
and Management, 16:2, 230-237
To link to this article: http://dx.doi.org/10.3846/jcem.2010.26
Published online: 14 Oct 2010.
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Citing articles: 10 View citing articles
2. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT
2010
16(2): 230–236
BUCKLING OF SLENDER COMPOSITE CONCRETE-FILLED STEEL COLUMNS
C. Douglas Goode1
, Artiomas Kuranovas2
, Audronis Kazimieras Kvedaras3
1
University of Manchester, Manchester, M13 9PL, UK
2, 3
Vilnius Gediminas Technical University, Saulėtekio al. 11, LT-10223 Vilnius, Lithuania
E-mails: 1
cdgoode@ukonline.uk; 2
artiomas.kuranovas@vgtu.lt; 3
audronis-kazimieras.kvedaras@vgtu.lt
Received 30 Oct. 2009; accepted 11 Feb. 2010
Abstract. The paper presents the analysis of the experimental data of 1817 on concrete-filled steel tubes – CFSTs. These
results are compared with the predicted results of the load-bearing capacity of calculations of slender elements according
to the methods suggested by Eurocode 4. The following types of tested CFSTs were analysed: circular and rectangular
hollow section stub and long columns fully filled with concrete, which were with or without applied moments at the ends
of specimen. During the results obtained in the result of the tests on the load bearing capacity for circular concrete-filled
steel tubular columns correspond with the calculated values based on methods presented by Eurocode 4. The experimental
values of load bearing capacity for members of concrete-filled rectangular hollow sections agree very well with the theo-
retical values where the concrete cylinder strength is below 75 N/mm2
. The analysis demonstrated that preloading of con-
crete-filled hollow section members does not influence the load bearing capacity.
This paper also presents the examination of stress state distribution for concrete-filled hollow section members, influence
of concrete preloading and of longitudinal stress strain curves.
Keywords: concrete-filled steel columns, buckling, slenderness, load-bearing capacity, Eurocode 4, analysis, comparison,
test results.
1. Introduction
Steel structural hollow sections are the most efficient of all
the structural sections in resisting compression load. And
filling these sections with plain concrete significantly in-
creases load-bearing capacity. CFST columns have a num-
ber of advantages as follows: a) it combines tension prop-
erties of steel and compression properties of concrete and
provides the hollow steel sections with greater strength and
stiffness, b) the confinement of concrete by steel enhances
failure strength of concrete, c) column size may be reduced
more than necessary for pure steel or RC column and pro-
vide greater floor area for use, d) the steel tube provides the
permanent formwork for concrete, e) steel tube column can
be erected rapidly for a number of storey heights, allowing
to add floors before filling tubes with concrete, f) good
seismic resistance because of good ductility and high en-
ergy absorbing properties, etc. (Kvedaras et al. 2006, 2009;
Partaukas and Bareisis 2009; Benzaid et al. 2008;
Soundararajan et al. 2008; Kuranovas et al. 2007; Goode
2007; Kuranovas and Kvedaras 2007; Kudzys et al. 2006;
Kuranovas 2006; Eurocode 4 2005; Han et al. 2004;
Baochung and Hiroshi 2003; Gopal and Manoharan 2003;
Han and Yao 2002, 2003; Han and Yang 2003; Chung et
al. 2001; Han 2000; DL/T5085 1999; Zhang and Zhong
1999; Zhong 1999).
The main disadvantage is the degradation of steel
properties when exposed to fire, but these elements may
be protected by spraying fire retardants to outer surface of
the steel tube or by using plasterboard and rock-wool
insulation. Furthermore, load-bearing capacity under fire
may be improved by using internal reinforcement bars.
Different approaches and design philosophies were
adopted in different design codes of different count-
ries. But still in present time it is a lack of information
for designers: investigations, test results, FEM and struc-
tural analyses are necessary to derive more precise and
evaluating safer methods for such type elements. That’s
why C. D. Goode started collecting data for database,
analysed it and proposed new suggestions how to predict
more precisely load-bearing capacity of various type
CFST elements under various type loading.
2. Codes and test data
Different limitations on the compressive strength of con-
crete, steel yield strength, diameter-to-thickness ratio;
steel ration and confining coefficient are prescribed in
different codes (Xinbo et al. 2006). These limitations are
compared in Table 1 (Kuranovas et al. 2009); where
ckcaya fAfA /5,1=ξ , is the 150 mm cube compres-
sive strength of concrete; – is the yield strength of
steel tube, , are areas of steel tube and concrete
core respectively, is steel ratio; and E is the elasticity
modulus of steel tube.
ckf
ayf
aA cA
aa
JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT ISSN 1392–3730 print / ISSN 1822–3605 online
http:/www.jcem.vgtu.lt doi:10.3846/jcem.2010.26
230
3. Journal of Civil Engineering and Management, 2010, 16(2): 230–236 231
Table 1. Comparison of the limitations in different codes
Item
CHN-JCJ
01-89
CHN CECS
CHN-DL/T
5085
ckf 30~50 30~80 30~80
ayf 235~345 235~420 235~390
atD/ ~ 20~ ayf/23590 20~100
aa 0,04~0,16 – 0,04~0,20
ξ – 0,03~0,3 –
Item
AISC-
LRFD(99)
Eurocode 4 JAN-AIJ(97)
ckf 26~65 25~60
ayf ≤ 415 235~355
atD/ ayfE /8≤ ayf/23590≤ ayf/35280≤
aa ≥ 0,04 – –
ξ – – –
The limitations and conditions for composite co-
lumns and composite compression members according to
EC4 are: a) the steel grade should be S235 to S460,
b) concrete of strength classes C20/25 to C50/60, c) local
buckling can be neglected if )/23552/( yfht > and
)/23590/( yfDt > for columns of circular and rectan-
gular cross section respectively.
Overall buckling is allowed for in the EC4 by intro-
ducing a buckling factor related to the relative slender-
ness
χ
λ by the European buckling curve:
⎟
⎠
⎞⎜
⎝
⎛ λ−ϕ+ϕ=χ )(/1 22
,
where: ))2.0(1·(5.0 2
λ+−ϕα+=ϕ and
crRdPl NN /,=λ ,
21.0=α – for any added reinforcement being ≤ 3% and
34.0=α – for 3% < sρ ≤ 6%;
cas AA /100×=ρ ;
fsdscdcdyaRdPl fAfAfAN ++= ,, – plastic compres-
sion resistance;
22
/)( LEIN effcr π= – the elastic critical load;
ccmssaaeff IEIEIEEI 6.0)( ++= .
When columns are loaded by end moment two me-
thods of analysis can be applied:
1. Simplified method, where the second-order ef-
fects are allowed for by multiplying the first-order ap-
plied moments by a factor ‘k’;
2. More precisely method, where the second order
effect is analysed.
For columns with equal end moments ‘k’ is given by:
.00.1))/(1/(10,1 , ≥−= effcru NNk
In the simplified method the calculated moment resis-
tance has been divided by the ‘k’ factor to compare with
the test result (rather than factoring the test result by ‘k’)
and the failure load predicted by the code is compared with
the test result at the same axial load/moment ratio as was
used in the test. Fig. 1 illustrates this where the Eurocode 4
curve allows for slenderness (χ), the steel grade factor
Mα , and the ‘k’ factor. Factor has been taken as 0.9,
when steel yield strength in the test was less than
420 N/mm
Mα
2
and 0.8, when greater than this.
Thus in the EC 4 curve Eu-
rocode 4 states that second-order effects need not be con-
sidered and that when the applied load divided by the elas-
tic critical load is less than 0.1, ‘k’ may be taken as unity.
./ kMM MECA ×α×χ=
This results in a ‘step’ in the interaction diagram as
when < 0.1 then k = 1 but when =
0.1 then k = 1.22. Test results by Matsui et al. are also
effcrNN effcrNN ,/,/
4. C. D. Goode et al. Buckling of slender composite concrete-filled steel columns232
Fig. 1. Typical axial load–moment interaction curve. Note: The ‘step’ in the Eurocode 4 curve is because of
that ‘second-order effects need not be considered when < 0.1 the factor ‘k’ is unity but for
= 0.1 ‘k’ = 1.22
effcrEd NN ,/
effcrEd NN ,/
JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT ISSN 1392–3730 print / ISSN 1822–3605 online
http:/www.jcem.vgtu.lt doi:10.3846/jcem.2010.26
232
5. Journal of Civil Engineering and Management, 2010, 16(2): 230–236 233
shown (Goode 2009). When the ‘second order’ method is
used the lateral deflection of the column at mid-height
caused by the end moment was added to the end eccen-
tricity of the load to give the second-order moment and it
is the load at this moment on the second-order curve
which is compared to the failure load of the column.
In this paper data of results were used to form website
database (http://web.ukonline.co.uk/asccs2) (Eurocode 4
2005), which collects together information for 1819 tests of
CFSTs and compares the test results with EC4; some typi-
cal graphs are also included into this paper.
The data collected in the database is subdivided into
“long” ( ) columns of “circular” and “square”
cross-section (Fig. 2).
4)(/ >BDL
a) b) c) d)
Fig. 2. Long CFST slenderness columns :4)(/ >BDL
a) circular CFST with no moment, b) circular with moment,
c) square CFST with no moment, d) square CFST with moment
The information required and reported for each test
is: outer diameter (D) if circular cross-section, or breath
(B) and depth (H) if rectangular one; the thickness ( ) of
the steel tube; the steel properties ( ) and, for slender
columns, modulus of elasticity ( ); the concrete proper-
ties (concrete yield strength ( ), ( in Goode 2008)
and, for long columns, its secant modulus of elasticity
( ) to )); the length ( ) of the column; the
maximum load achieved by the column in test ( = Test
failure load). For columns with an end moment the initial
eccentricity of load at the top ( ) and bottom ( ) is
required.
at
ayf
aE
cylf ckf
cE ckf4,0 L
uN
te be
Dispersions of EC4 vs. test and ratio test/EC4 vs.
concrete strength for LS and LSM are presented in
Figs 7–8 and 9–10 respectively.
Summary results of LC, LCM, LS and LSM are pre-
sented in Table 2 (Yamamoto et al. 2000), where it can be
seen that the average values of test/EC 4 for each type of
column are higher than Eurocode 4 predicts.
Dispersions EC4 vs. test and ratio test/EC4 vs. concrete
strength for slenderness elements are shown in Figs 3–10.
Fig. 3. Tests results of LC concrete-filled steel columns
compared with calculations according to (Goode 2008)
Fig. 4. Ratio test/EC4 vs. slenderness of LC concrete-filled
steel columns
Fig 5. Tests results of LCM concrete-filled columns compared
with calculations according to (Goode 2008)
Fig. 6. Ratio Test/EC4 vs. concrete cylinder strength of LCM
concrete-filled steel columns
6. C. D. Goode et al. Buckling of slender composite concrete-filled steel columns234
Fig. 7. Tests results of LS concrete-filled steel columns
compared with calculations according to (Goode 2008)
Fig. 8. Ratio test/EC4 vs. concrete strength for LS concrete-
filled steel columns
Fig. 9. Tests results of LSM concrete-filled steel columns
compared with calculations according (Goode 2008)
Fig. 10. Ratio test/EC4 vs. concrete cylinder strength of LSM
concrete-filled steel columns
The ‘failed tests’ column of Table 2 shows the pe-
rcentage of all tests failed before reaching the resistance
calculated by EC4 methods.
The last column shows this percentage for the co-
lumns, which met all conditions indicated in Eurocode 4.
Table 3 (Yamamoto et al. 2000) shows a comparison
between average test/EC 4 ratio for different concrete
strengths and also the local buckling criteria for the diffe-
rent types of column. For LC type of concrete-filled steel
column, there occurred few ‘unsafe’ results, when the
concrete cylinder strength was outside 20 to 50 N/mm2
cylinder strength permitted by Eurocode 4 than when
within this range. For the long square concrete-filled
columns, a decrease in the test/EC4 ratio may be obser-
ved after high strength concrete has been used for the
LCM type.
For circular section columns with an applied end
moment, the simplified ‘k’ factor method and the ‘second
order’ analysis showed very similar results; see Fig. 11
(Yamamoto et al. 2000). However, for rectangular col-
umns the second order analysis predicted, in general,
lower (safer) failure loads than the ‘k’ factor method and
often much lower than achieved during the tests. Note
that about 17% of all the circular and rectangular tests
failed below their predicted failure load. The average
test/EC 4 ratio for the 1027 tests analysed in this paper
was 1.14 demonstrating standard deviation of 0.114.
3. Analysis of other type structures and loadings
Hollow Sections
The 76 hollow circular section and the 24 hollow
square, 8-sided or 16-sided section columns without ben-
ding behaved in a similar way to the solid sections when
allowance was made for the hole. The average test/EC 4
ratios were 1.22 for the circular sections and 1.16 for the
other sections.
Preload and Sustained Load
Pre-load (up to 60% of the capacity of the steel) on
the steel tube before filling with concrete seems to have
no effect on the strength; the average test/ EC 4 for the 23
circular columns (11 short and 12 long) being 1.15 (Stan-
dard deviation 0.123) and for the 19 rectangular columns
(10 short and 9 long) being 1.03 (Standard deviation
0.099). The eight tests, which sustained an average load
of between 53% and 63% of their capacity for 120 or 180
days before being loaded to failure, carried a slightly
higher load before failing (average test/EC 4 = 1.25) than
their six comparison tests without sustained load (average
test/EC 4 = 1.08).
Yamamoto (2000) and Zhang et al.(2007) tested
short circular concrete specimens with steel encasing the
concrete and the axial load applied only to the concrete
and not to the steel. Their results show that stub columns
so loaded were able to sustain a higher load (19 tests
test/EC 4 = 1.13) than similar sections where the load
was applied uniformly over both steel and concrete (15
tests test/EC 4 = 1.03).
7. Journal of Civil Engineering and Management, 2010, 16(2): 230–236 235
Table 2. Summary of results for each type of column
% where Test/EC4 < 1
Tests which satisfy EC4Type of column
NO. OF
Tests
AVE
Test/EC4
ST. DEV.
of Test/EC4 Failed tests
% < 1 % < 1
LC 369 1.17 0.148 16% 306 11%
254 1.15 0.111 16% 198 10%LCM ‘k’ factor method
2nd
order analysis 254 1.15 0.119 22% 198 18%
LS 212 1.06 0.097 35% 76 30%
96 1.11 0.098 18% 26 19%LSM ‘k’ factor method
2nd
order analysis 96 1.20 0.148 11% 26 4%
Totals 1027 1.14 0.120 20% 830 15%
Table 3. Comparison of Test/EC4 for different concrete strengths and for local buckling criteria
fcyl ≤ 50 N/mm2
fcyl > 60 N/mm2
fcyl > 75 N/mm2 Local buckling criteria
satisfied
Local buckling ‘likely’Type of
column
Ave % < 1 Ave % < 1 Ave % < 1 No Ave % < 1 No Ave % < 1
LC 1.19 14 1.08 29 1.00 63 334 1.19 14 35 1.06 37
LR 1.05 40 1.09 26 1.04 35 130 1.07 32 82 1.05 40
LCM 1.18 10 1.05 34 1.01 56 255 1.15 16 none
LRM 1.09 31 1.10 11 0.98 75 60 1.14 13 65 1.03 42
Fig. 11. Columns with moment; comparison of ‘k’ factor analysis with 2nd order analysis
8. C. D. Goode et al. Buckling of slender composite concrete-filled steel columns236
Biaxial Bending
Only 11 tests on rectangular columns with biaxial ben-
ding are reported and these all failed at much higher loads
than predicted by Eurocode 4, average test/EC 4 was
1.52. The Code uses a straight line interaction for the
bending resistance between the two axes with an additio-
nal safety factor , (withMα Mα as 0.9 for steel grades
S235 to S355 and 0.8 for steel grades S420 and S460).
Using an elliptical interaction between the moments
about the two axes and omitting this additional safety
factor, i.e. = 1, gives much closer agreement with
the test failure load, an average test/prediction of 1.20 for
these 11 tests (Goode 2008, 2009).
Mα
4. Summary and future perspectives
Eurocode 4 predicts safe methods of strength evaluation
for slender LC and LCM concrete-filled columns and
could be safely used for concrete with cylinder strength
up to 100 N/mm2
. And C.D. Goode’s opinion that for
circular section columns the Code limitation on concrete
cylinder strength could be safely extended to 75 N/mm2
.
For rectangular section CFST columns Eurocode 4
should be used with caution, when the concrete cylinder
strength is greater than 75N/mm2
as the failure load in the
majority of tests when > 75 N/mmcylf 2
was less than that
predicted by the EC4 approach (Note: EC4 limits the
concrete strength to 50 N/mm2
).
C.D.Goode states that the concrete strength limita-
tion for rectangular section columns could be safely ex-
tended to 60 N/mm2
. When higher strength concrete is
used, its cylinder strength should be factored by 0.85,
equivalent to assumption that no enhancement of concrete
strength should be experienced due to containment.
Sections, both circular and rectangular, which have
a wall thickness thinner than permitted (Goode 2008) by
the local buckling could be used if a factor of 0.75 was
applied to the resistance predicted by Eurocode 4.
The simplified ‘k’ factor method and second order
analysis of Eurocode 4 showed similar results.
Further investigations, tests, FEM and structural
analyses are required.
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LIAUN Ų KLUPUMAS
C. D. Goode, A. Kuranovas, A. K. Kvedaras
S a n t r a u k a
šerdžių plieninStraipsnyje aptariami 1817 beton
su rezultatais, gautai
Analizuojami tokie betonšerdžių plieninių strypų bandinių tipai: pilnavidurės trumpos arba liaunos apskritojo ir stačia-
kampio skerspjūvio vamzdinės betonšerdės plieninės kolonos su jų galuose veikiančiu lenkiamuoju momentu arba be jo.
Apskritojo skerspjūvio betonšerdžių kolonų bandymų metu gautieji laikomosios galios rezultatai atitinka remiantis Euro-
code 4 pateiktais metodais apskaičiuotąsias jų reikšmes. Stačiakampio skerspjūvio betonšerdžių elementų laikomosios ga-
lios bandymais rastosios reikšmės labai gerai atitinka teorines reikšmes, kai šerdies betono ritininis stipris nesiekia
75 N/mm2
. Analizuojant nustatyta, kad išankstinis betonšerdžių elementų apkrovimas neturi beveik jokio poveikio ele-
mentų laikomajai galiai. Šiame straipsnyje taip pat nagrinėjamas betonšerdžių elementų įtempių būvių pasiskirstymas, be-
tono apspaudimo poveikis bei išilginių deformacijų ir įtempių kreivės.
Reikšminiai žodžiai: kompozitinės konstrukcijos, betonšerdės plieninės vamzdinės kolonos, Eurocode 4, skaičiavimas,
lyginimas, liaunumas, klupumas, laikomoji galia, bandymo rezultatai.
D
C
filled steel tubular columns. Research interests: steel, concrete, composite steel and concrete structures.
Artiomas KURANOVAS. PhD student at the Department of Steel and Timber Structures, Vilnius Gediminas Technical
University, Lithuania. A graduate of Civil Engineering at Vilnius Gediminas Technical University (20
Engineering (2004) at Vilnius Gediminas Technical University. He is a member of the Council on Tall Buildings and Ur-
ban Habitat (CTBUH) and the International Association for Steel-Concrete Composite Structures (ASCCS). Research in-
terests: structural mechanics, composite elements and behaviour of their components, engineering software for design of
structural elements.
Audronis Kazimieras KVEDARAS. Dr Habil Professor at the Department of Steel and Timber Structures and Director
of the Innovatory Sci
is a member of the International Association for Bridge and Structural Engineering (IABSE) and ASCCS, invited NATO
expert (1996, 2000). Research interests: steel, composite steel-concrete and timber-concrete structures.