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.
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.
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 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.
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
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 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.
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.
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 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.
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
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 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.
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.
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.
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.
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.
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.
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.
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.
Buckling of slender composite concrete filled steel columnsRadhwan Faraj
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.
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.
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- 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.
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- 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 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 presents an experimental and analytical study comparing the structural behavior of composite concrete slabs with profiled steel decking. 18 full-scale slab specimens were tested under different shear span lengths to evaluate the longitudinal shear bond strength between the concrete and steel deck. The experimental results were compared to analytical calculations using the m-k method and partial shear connection method from Eurocode 4. The m-k method was found to provide a more conservative estimate of load-carrying capacity than the partial shear connection method, with generally good agreement between experimental and analytical values.
Experimental Testing Of Partially Encased Composite Beam ColumnsIJERA Editor
The past few decades have seen outstanding advances in the use of composite materials in structural applications. There can be little doubt that, within engineering circles, composites have revolutionized traditional design concepts and made possible an unparalleled range of new and exciting possibilities as viable materials for construction. In addition to the well-known advantages of composite columns, partially encased composite columns offered simplified beam-to-column connection as well as reduced or omitted shuttering thus achieved more cost effective construction. Some companies have patented these new types of partially encased composite column made of light welded steel shapes; moreover, the Canadian Institute of Steel construction CISC has recognized and codified this type of columns. In This paper, Partially Encased Composite Beam Columns is introduced; experimental studies are made on five partially encased beam columns to investigate the behavior of eccentrically loaded partially encased composite columns using different parameters.
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.
Flexural behavior of composite reinforced concrete t beams cast in steel cha...IAEME Publication
The document summarizes an experimental study on the flexural behavior of composite reinforced concrete T-beams with horizontal transverse bars as shear connectors. Three large-scale beam specimens were fabricated, loaded until failure, and their load-deflection responses were measured. Results showed that beams with horizontal bar shear connectors had substantially higher ultimate bending capacity, flexural stiffness, and integrity compared to previous studies using headed stud connectors. The use of horizontal bars as shear connectors provides improved flexural performance of composite concrete beams cast in steel channels.
This document reviews research on the bond strength between steel and concrete in concrete-filled steel tubes (CFSTs). It summarizes several studies that investigated factors affecting bond strength like cross-sectional dimensions, steel type, concrete properties, temperature, and interface characteristics. The review finds that 70% of bond strength comes from friction at the interface, while 30% comes from chemical adhesion and mechanical interlocking. It also identifies ways to improve bond strength, such as using expansive concrete, increasing concrete strength, and adding perforations to the steel tube interior.
State of The Art Report on Steel-Concrete In filled Composite ColumnIJERA Editor
Steel-concrete composite systems for buildings are composed of concrete components that interact with
structural steel components within the same system. By their integral behavior, these components give the
required attributes of strength, stiffness and stability to the overall system. Composite members, as individual
elements of a system, have been in use for a considerable number of years. They consist of composite columns
or trusses, encased or filled composite columns, and steel deck reinforced composite slabs. In this paper, a
review of the research carried out on composite columns with infills is given with emphasis on experimental
work.
This document summarizes an experimental study on the behavior of interior beam-column joints in reinforced concrete frames wrapped with fiber-reinforced polymer (FRP). Sixteen beam-column joint specimens were tested under cyclic loading, with variations in reinforcement detailing per Indian codes IS 456-2000 and IS 13920-1993, and use of FRP wrapping and fiber-reinforced concrete. The results showed that joints designed according to IS 13920-1993 had smaller cracks and higher load capacity than those per IS 456-2000. FRP wrapping and fiber-reinforced concrete improved joint ductility, increasing maximum deflection by up to 25% compared to unwrapped specimens. Specimens with two layers of FRP wrapping and 0.
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.
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.
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.
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.
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.
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.
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.
Buckling of slender composite concrete filled steel columnsRadhwan Faraj
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.
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.
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- 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.
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- 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 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 presents an experimental and analytical study comparing the structural behavior of composite concrete slabs with profiled steel decking. 18 full-scale slab specimens were tested under different shear span lengths to evaluate the longitudinal shear bond strength between the concrete and steel deck. The experimental results were compared to analytical calculations using the m-k method and partial shear connection method from Eurocode 4. The m-k method was found to provide a more conservative estimate of load-carrying capacity than the partial shear connection method, with generally good agreement between experimental and analytical values.
Experimental Testing Of Partially Encased Composite Beam ColumnsIJERA Editor
The past few decades have seen outstanding advances in the use of composite materials in structural applications. There can be little doubt that, within engineering circles, composites have revolutionized traditional design concepts and made possible an unparalleled range of new and exciting possibilities as viable materials for construction. In addition to the well-known advantages of composite columns, partially encased composite columns offered simplified beam-to-column connection as well as reduced or omitted shuttering thus achieved more cost effective construction. Some companies have patented these new types of partially encased composite column made of light welded steel shapes; moreover, the Canadian Institute of Steel construction CISC has recognized and codified this type of columns. In This paper, Partially Encased Composite Beam Columns is introduced; experimental studies are made on five partially encased beam columns to investigate the behavior of eccentrically loaded partially encased composite columns using different parameters.
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.
Flexural behavior of composite reinforced concrete t beams cast in steel cha...IAEME Publication
The document summarizes an experimental study on the flexural behavior of composite reinforced concrete T-beams with horizontal transverse bars as shear connectors. Three large-scale beam specimens were fabricated, loaded until failure, and their load-deflection responses were measured. Results showed that beams with horizontal bar shear connectors had substantially higher ultimate bending capacity, flexural stiffness, and integrity compared to previous studies using headed stud connectors. The use of horizontal bars as shear connectors provides improved flexural performance of composite concrete beams cast in steel channels.
This document reviews research on the bond strength between steel and concrete in concrete-filled steel tubes (CFSTs). It summarizes several studies that investigated factors affecting bond strength like cross-sectional dimensions, steel type, concrete properties, temperature, and interface characteristics. The review finds that 70% of bond strength comes from friction at the interface, while 30% comes from chemical adhesion and mechanical interlocking. It also identifies ways to improve bond strength, such as using expansive concrete, increasing concrete strength, and adding perforations to the steel tube interior.
State of The Art Report on Steel-Concrete In filled Composite ColumnIJERA Editor
Steel-concrete composite systems for buildings are composed of concrete components that interact with
structural steel components within the same system. By their integral behavior, these components give the
required attributes of strength, stiffness and stability to the overall system. Composite members, as individual
elements of a system, have been in use for a considerable number of years. They consist of composite columns
or trusses, encased or filled composite columns, and steel deck reinforced composite slabs. In this paper, a
review of the research carried out on composite columns with infills is given with emphasis on experimental
work.
This document summarizes an experimental study on the behavior of interior beam-column joints in reinforced concrete frames wrapped with fiber-reinforced polymer (FRP). Sixteen beam-column joint specimens were tested under cyclic loading, with variations in reinforcement detailing per Indian codes IS 456-2000 and IS 13920-1993, and use of FRP wrapping and fiber-reinforced concrete. The results showed that joints designed according to IS 13920-1993 had smaller cracks and higher load capacity than those per IS 456-2000. FRP wrapping and fiber-reinforced concrete improved joint ductility, increasing maximum deflection by up to 25% compared to unwrapped specimens. Specimens with two layers of FRP wrapping and 0.
This study experimentally investigated the effect of steel fibers on the flexural behavior and ductility of high-strength concrete hollow beams. Eight square beams (four solid and four hollow) were cast with concrete containing 0%, 0.5%, 1.0%, or 1.5% steel fibers by volume. The hollow beams had a central square hole that reduced the cross-sectional area by about 28%. All beams were tested under four-point bending until failure. Test results showed that beams with steel fibers failed in flexure, while the beam without fibers failed in flexural-shear. In general, hollow beams exhibited better ductility than solid beams. Hollow beams with up to 1.0% fibers had lower cracking, yielding,
FINITE ELEMENT ANALYSIS OF STEEL BEAM-CFST COLUMN JOINTS CONFINED WITH CFRP B...IRJET Journal
This document discusses a finite element analysis of steel beam-concrete filled steel tube (CFST) column joints confined with carbon fiber reinforced polymer (CFRP) belt and rebar. A literature review is conducted on square and circular CFST columns. The study aims to determine the optimal arrangement of CFRP joint belt and rebar in connecting beams and CFST columns. Various CFRP belt layouts are modeled and analyzed using ANSYS software to improve the load carrying capacity of the beam-column connection system. The structural components are modeled using different element types and materials properties. Boundary conditions and meshing are applied to simulate the structural behavior under an applied load. The analysis results will help identify the best CFRP belt
This document summarizes a master's thesis that experimentally and numerically studied the pull-out behavior of steel fibers in concrete. Experiments were conducted on straight and hooked steel fibers under various lateral pressures. The experiments showed large variations in results partly due to local crushing of the cement matrix. A numerical model was developed using an interface damage model and contact simulation to model fiber-concrete bonding. The model studies the influence of heterogeneous concrete properties on hooked fiber pull-out behavior by varying cement, aggregate, and interface strengths and toughnesses. Simulated results agreed with experiments, showing local concrete fracture influences pull-out behavior.
IRJET- Experimental Investigation on Bond Strength in Self-Compacting Con...IRJET Journal
The document summarizes an experimental study on the bond strength between self-compacting concrete and steel tubes in concrete-filled steel tube (CFST) columns. 27 push-out tests were conducted on circular CFST specimens varying cross-sectional dimensions, steel type, concrete type (normal vs self-compacting), concrete age, and height-to-diameter ratio. A literature review covered previous studies investigating effects of dimensions, steel type, concrete strength and interfaces on bond strength. The objectives were to use self-compacting concrete in CFSTs, determine bond strength for different ratios and properties, and model bond strength prediction.
Ultimate Behavior of Lightweight High Strength Concrete Filled Steel Tube (LW...IOSR Journals
This document summarizes research on the ultimate behavior of lightweight high strength concrete filled steel tube (LWHCFST) bridges. The researchers conducted compression tests on LWHCFST cylinders to determine the concrete's strength and modulus of elasticity. They then used finite element analysis to model an example arch bridge made with hollow steel tubes, normal strength concrete filled steel tubes, and LWHCFST. The analysis found that the bridge failed under the highest load when made with LWHCFST, indicating it can support longer spans than alternatives while maintaining strength. In conclusion, LWHCFST is beneficial for bridge design by reducing weight without compromising load capacity.
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.
Behaviour of Steel Fibre Reinforced Concrete Beam under Cyclic LoadingIOSR Journals
Abstract: This paper describes the influence of steel fibre distribution on the ultimate strength of concrete
beams. An experimental & analytical investigation of the behaviour of concrete beams reinforced with
conventional steel bars and steel fibres under cyclic loading is presented. It is now well established that one of
the important properties of steel fibre reinforced concrete (SFRC) is its superior resistance to cracking and
crack propagation. As a result of this ability to arrest cracks, fibre composites possess increased extensibility
and tensile strength, both at first crack and at ultimate load and the fibres are able to hold the matrix together
even after extensive cracking. The net result of all these is to impart to the fibre composite pronounced post –
cracking ductility which is unheard of in ordinary concrete. The transformation from a brittle to a ductile type
of material would increase substantially the energy absorption characteristics of the fibre composite and its
ability to withstand repeatedly applied, shock or impact loading. Tests on conventionally reinforced concrete
beam specimens, containing steel fibres in different proportions, have been conducted to establish loaddeflection
curves. It was observed that SFRC beams showed enhanced properties compared to that of RC beams
with steel fibres. The experimental investigations are validated with the analytical studies carried out by finite
element models using ANSYS.
Keywords: Steel fiber, concrete, properties, crack, ductility, technology.
Final paper for thesis on Steel tubular columnAL AMIN AZIZ
This thesis paper was completed by myself at the time of my Graduation in Civil Engineering from RUET. I am now publishing this paper so that it could help someone and they can run the further implementation of the future scope of this paper.
Flexural and Torsional Behavior of Concrete Filled Tubular Flange GirderIRJET Journal
This document summarizes research on concrete filled tubular flange girders (CFTFGs). CFTFGs have a steel tube filled with concrete as the upper flange, which increases stiffness and allows the section to carry more load compared to a standard steel beam. The document reviews several studies that analyzed the flexural and torsional behavior of CFTFGs using finite element analysis and experiments. The studies found that filling the flange with concrete improves strength and stability. However, the moment capacity is reduced under axial tensile forces in the steel. The concrete filling also limits the axial tensile resistance to the plastic capacity of the steel alone.
Comprehensive study of high strength fiber rienforced concrete under pull out...IAEME Publication
This document presents a study on the pullout strength of high-strength steel fiber reinforced concrete. Concrete cubes containing steel fibers ranging from 0.5% to 5% by weight of cement were tested. The following key points are discussed:
1) Workability decreases with higher fiber content, so superplasticizer was used. Steel fibers increase the ductility and bond strength of concrete.
2) New expressions for predicting pullout strength as a function of fiber volume fraction and bond strength were proposed based on regression analysis.
3) Maximum fiber content was found to be dependent on concrete strength. The inclusion of steel fibers provided a significant improvement in pullout strength.
COMPREHENSIVE STUDY OF HIGH STRENGTH FIBER REINFORCED CONCRETE UNDER PULL OUT...IAEME Publication
The present work deals with an experimental investigation and results obtained on the high strength steel fiber reinforced concrete. The effects of these fibers on workability, density, and on various strengths of high strength concrete (M60 grade concrete) are studied. Present paper emphasises on the Pullout strength of concrete. The fiber content varied from 0.5 to 5% by weight of cement at the interval of 0.5 %. Concrete cubes of 150x150x150 mm with 16mm tor bar embedded
in concrete at the centre of the cube were casted. All the specimens are water cured and tested at the age of 7 and 28 days. Workability of wet mix is found to be reduced with increased fiber content. Super plasticizer is used to increase workability.
Dynamic Analysis of Double-Skin Composite Steel PlatesIOSR Journals
1) The document analyzes dynamic finite element models of double-skin composite steel plates subjected to impact loading. A rigid penetrator impacts composite panels made of steel skins separated by a concrete core with shear stud connectors.
2) Results show that the panels have good energy absorption capacity due to the ductility of the lower steel plate and stiffness provided by lower shear studs. Increasing the upper or lower plate thickness, or concentrating more studs in the center, increases the energy absorbed before perforation.
3) The failure patterns are investigated. Under impact, the upper plate initially perforates and moves upward due to inertia effects. The upper studs increase plate stiffness. Concrete failure is more localized than under static
A Study on Effect of Sizes of aggregates on Steel Fiber Reinforced ConcreteIJERD Editor
Plain, unreinforced concrete is a brittle material, with a low tensile strength, limited ductility and
little resistance to cracking. In order to improve the inherent tensile strength of concrete there is a need of
multidirectional and closely spaced reinforcement, which can be provided in the form of randomly distributed
fibers. Steel fiber is one of the most commonly used fibers The present experimental study considers the effect
of aggregate size and steel fibers on the modulus of elasticity of concrete. Crimped steel fibers at volume
fraction of 0%.0.5%, 1.0% and 1.5% were used. Study on effect of volume fraction of fibers and change of
aggregate size on the modulus of elasticity of concrete was also deemed as an important part of present
experimental investigation. This work aims in studying the mechanical behavior of concrete in terms of modulus
of elasticity with the change of aggregate size reinforced with steel fibers of different series for M30 and M50
grade concretes. The results obtained show that the addition of steel fiber improves the modulus of elasticity of
concrete. It was also analyzed that by increasing the fiber volume fraction from 0%, to 1.5% there was a healthy
effect on modulus of elasticity of Steel Fiber Reinforced concrete.
Experimental Testing Of Partially Encased Composite Beam ColumnsIJERA Editor
The past few decades have seen outstanding advances in the use of composite materials in structural
applications. There can be little doubt that, within engineering circles, composites have revolutionized
traditional design concepts and made possible an unparalleled range of new and exciting possibilities as viable
materials for construction.
In addition to the well-known advantages of composite columns, partially encased composite columns offered
simplified beam-to-column connection as well as reduced or omitted shuttering thus achieved more cost
effective construction. Some companies have patented these new types of partially encased composite column
made of light welded steel shapes; moreover, the Canadian Institute of Steel construction CISC has recognized
and codified this type of columns.
In This paper, Partially Encased Composite Beam Columns is introduced; experimental studies are made on five
partially encased beam columns to investigate the behavior of eccentrically loaded partially encased composite
columns using different parameters
IRJET-Experimental behavior of Concrete under Compression Load with Steel Fib...IRJET Journal
This document summarizes research on the experimental behavior of concrete under compression load when partially replacing cement with steel fiber and ferrocement. The research involved casting and testing cylinders and cubes of M25 grade concrete with different mixes - some with steel fiber and ferrocement additions and others without. The results showed that concrete with a 0.5% addition of steel fiber and no ferrocement layers had the highest ultimate strain and a 16% increase in compressive strength compared to plain concrete cubes. The research concluded that steel fiber and ferrocement additions can improve the performance and properties of concrete under compression loads.
Experimental behavior of circular hsscfrc filled steel tubular columns under ...eSAT Journals
This document summarizes an experimental study that tested circular concrete-filled steel tube columns with varying parameters. 45 specimens were tested with different fiber percentages (0-2%), tube diameter-to-wall-thickness ratios (D/t from 15-25), and length-to-diameter (L/d) ratios (from 2.97-7.04). The results found that columns filled with fiber-reinforced concrete exhibited higher stiffness, equal ductility, and enhanced energy absorption compared to those filled with plain concrete. The load carrying capacity increased with fiber content up to 1.5% but not at 2.0%. The analytical predictions of failure load closely matched the experimental values.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Experimental behavior of circular hsscfrc filled steel tubular columns under ...eSAT Journals
Abstract
This paper presents an outlook on experimental behavior and a comparison with predicted formula on the behaviour of circular
concentrically loaded self-consolidating fibre reinforced concrete filled steel tube columns (HSSCFRC). Forty-five specimens were
tested. The main parameters varied in the tests are: (1) percentage of fiber (2) tube diameter or width to wall thickness ratio (D/t
from 15 to 25) (3) L/d ratio from 2.97 to 7.04 the results from these predictions were compared with the experimental data. The
experimental results) were also validated in this study.
Keywords: Self-compacting concrete; Concrete-filled steel tube; axial load behavior; Ultimate capacity.
Similar to Finite Element Analysis of Concrete Filled Steel Tube (CFT’s) Subjected to Flexure (20)
This document discusses the impact of data mining on business intelligence. It begins by defining business intelligence as using new technologies to quickly respond to changes in the business environment. Data mining is an important part of the business intelligence lifecycle, which includes determining requirements, collecting and analyzing data, generating reports, and measuring performance. Data mining allows businesses to access real-time, accurate data from multiple sources to improve decision making. Using business intelligence and data mining techniques can help businesses become more efficient and make better decisions to increase profits and customer satisfaction. The expected results of applying business intelligence include improved decision making through accurate, timely information to support organizational goals and strategic plans.
This document presents a novel technique for solving the transcendental equations of selective harmonics elimination pulse width modulation (SHEPWM) inverters based on the secant method. The proposed algorithm uses the secant method to simplify the numerical solution of the nonlinear equations and solve them faster compared to other methods. Simulation results validate that the proposed method accurately estimates the switching angles to eliminate specific harmonics from the output voltage waveform and achieves near sinusoidal output current for various modulation indices and numbers of harmonics eliminated.
This document summarizes a research paper that designed and implemented a dual tone multi-frequency (DTMF) based GSM-controlled car security system. The system uses a DTMF decoder and GSM module to allow a car to be remotely controlled and secured from a mobile phone. It works by sending DTMF tones from the phone through calls to the GSM module in the car. The decoder interprets the tones and a microcontroller executes commands to disable the ignition or control other devices. The system was created to improve car security and accessibility through remote monitoring and control with DTMF and GSM technology.
This document presents an algorithm for imperceptibly embedding a DNA-encoded watermark into a color image for authentication purposes. It applies a multi-resolution discrete wavelet transform to decompose the image. The watermark, encoded into DNA nucleotides, is then embedded into the third-level wavelet coefficients through a quantization process. Specifically, the watermark nucleotides are complemented and used to quantize coefficients in the middle frequency band, modifying the coefficients. The watermarked image is reconstructed through inverse wavelet transform. Extraction reverses these steps to recover the watermark without the original image. The algorithm aims to balance imperceptibility and robustness through this wavelet-based, blind watermarking scheme.
1) The document analyzes the dynamic saturation point of a deep-water channel in Shanghai port based on actual traffic data and a ship domain model.
2) A dynamic channel transit capacity model is established that considers factors like channel width, ship density, speed, and reductions due to traffic conditions.
3) Based on AIS data from the channel, the average traffic flow is calculated to be 15.7 ships per hour, resulting in a dynamic saturation of 32.5%, or 43.3% accounting for uneven day/night traffic volumes.
The document summarizes research on the use of earth air tunnels and wind towers as passive solar techniques. Key findings include:
- Earth air tunnels circulate air through underground pipes to take advantage of the stable temperature 4 meters below ground for cooling in summer and heating in winter. Testing showed the technique can reduce ambient temperatures by up to 14 degrees Celsius.
- Wind towers circulate air through tall shafts to cool air entering buildings at night and provide downward airflow of cooled air during the day.
- Experimental testing of an earth air tunnel system over multiple months found maximum temperature reductions of 33% in spring and minimum reductions of 15% in summer.
The document compares the mechanical and physical properties of low density polyethylene (LDPE) thin films and sheets reinforced with graphene nanoparticles. LDPE/graphene thin films were produced via solution casting, while sheets were made by compression molding. Testing showed that the thin films had enhanced tensile strength, lower melt flow index, and higher thermal stability compared to sheets. The tensile strength of thin films increased by up to 160% with 1% graphene, while sheets increased by 70%. Melt flow index decreased more for thin films, indicating higher viscosity. Thin films also showed greater improvement in glass transition temperature. These results demonstrate that processing technique affects the properties of LDPE/graphene nanocomposites.
The document describes improvements made to a friction testing machine. A stepper motor and PLC control system were added to automatically vary the load on friction pairs, replacing the manual method. Tests using the improved machine found that the friction coefficient decreases as the load increases, and that abrasive and adhesive wear increased with higher loads. The improved machine allows more accurate and convenient testing of friction pairs under varying load conditions.
This document summarizes a research article that investigates the steady, two-dimensional Falkner-Skan boundary layer flow over a stationary wedge with momentum and thermal slip boundary conditions. The flow considers a temperature-dependent thermal conductivity in the presence of a porous medium and viscous dissipation. Governing partial differential equations are non-dimensionalized and transformed into ordinary differential equations using similarity transformations. The equations are highly nonlinear and cannot be solved analytically, so a numerical solver is used. Numerical results are presented for the skin friction coefficient, local Nusselt number, velocity and temperature profiles for varying parameters like the Falkner-Skan parameter and Eckert number.
An improvised white board compass was designed and developed to enhance the teaching of geometrical construction concepts in basic technology courses. The compass allows teachers to visually demonstrate geometric concepts and constructions on a white board in an engaging, hands-on manner. It supports constructivist learning principles by enabling students to observe and emulate the teacher. The design process utilized design and development research methodology to test educational theories and validate the practical application of the compass. The improvised compass was found to effectively engage students and improve their performance in learning geometric constructions.
The document describes the design of an energy meter that calculates energy using a one second logic for improved accuracy. The meter samples voltage and current values using an ADC synchronized to the line frequency via PLL. It calculates active and reactive power by averaging the sampled values over each second. The accumulated active power for each second is multiplied by one second to calculate energy, which is accumulated and converted to kWh. Test results showed the meter achieved an error of 0.3%, within the acceptable limit for class 1 meters. Considering energy over longer durations like one second helps reduce percentage error in the calculation.
This document presents a two-stage method for solving fuzzy transportation problems where the costs, supplies, and demands are represented by symmetric trapezoidal fuzzy numbers. In the first stage, the problem is solved to satisfy minimum demand requirements. Remaining supplies are then distributed in the second stage to further minimize costs. A numerical example demonstrates using robust ranking techniques to convert the fuzzy problem into a crisp one, which is then solved using a zero suffix method. The total optimal costs from both stages provide the solution to the original fuzzy transportation problem.
1) The document proposes using an Adaptive Neuro-Fuzzy Inference System (ANFIS) controller for a Distributed Power Flow Controller (DPFC) to improve voltage regulation and power quality in a transmission system.
2) A DPFC is placed at a load bus in an IEEE 4 bus system and its performance is compared using a PI controller and ANFIS controller.
3) Simulation results show the ANFIS controller provides faster convergence and better voltage profile maintenance during voltage sags and swells compared to the PI controller.
The document describes an improved particle swarm optimization algorithm to solve vehicle routing problems. It introduces concepts of leptons and hadrons to particles in the algorithm. Leptons interact weakly based on individual and neighborhood best positions, while hadrons (local best particles) undergo strong interactions by colliding with the global best particle. When stagnation occurs, particle decay is used to increase diversity. Simulations show the improved algorithm avoids premature convergence and finds better solutions compared to the basic particle swarm optimization.
This document presents a method for analyzing photoplethysmographic (PPG) signals using correlative analysis. The method involves calculating the autocorrelation function of the PPG signal, extracting the envelope of the autocorrelation function using a low pass filter, and approximating the envelope by determining attenuation coefficients. Ten PPG signals were collected from volunteers and analyzed using this method. The attenuation coefficients were found to have similar values around 0.46, providing a potentially useful parameter for medical diagnosis.
This document describes the simulation and design of a process to recover monoethylene glycol (MEG) from effluent waste streams of a petrochemical company in Iran. Aspen Plus simulation software was used to model the process, which involves separating water, salts, and various glycols (MEG, DEG, TEG, TTEG) using a series of distillation columns. Sensitivity analyses were performed to optimize column parameters such as pressure, reflux ratio, and boilup ratio. The results showed that MEG, DEG, TEG, and TTEG could be recovered at rates of 5.01, 2.039, 0.062, and 0.089 kg/hr, respectively.
This document presents a numerical analysis of fluid flow and heat transfer characteristics of ventilated disc brake rotors using computational fluid dynamics (CFD). Two types of rotor configurations are considered: circular pillared (CP) and diamond pillared radial vane (DP). A 20° sector of each rotor is modeled and meshed. Governing equations for mass, momentum, and energy are solved using ANSYS CFX. Boundary conditions include 900K and 1500K isothermal rotor walls for different speeds. Results show the DP rotor has 70% higher mass flow and 24% higher heat dissipation than the CP rotor. Velocity and pressure distributions are more uniform for the DP rotor at higher speeds, ensuring more uniform cooling. The
This document describes the design and testing of an automated cocoa drying house prototype in Trinidad and Tobago. The prototype included automated features like a retractable roof, automatic heaters, and remote control. It aims to address issues with the traditional manual sun drying process, which is time-consuming and relies on human monitoring of changing weather conditions. Initial testing with farmers showed interest in the automated system as a potential solution.
This document presents the design of a telemedical system for remote monitoring of cardiac insufficiency. The system includes an electrocardiography (ECG) device that collects and digitizes ECG signals. The ECG signals undergo digital signal processing including autocorrelation analysis. Graphical interfaces allow patients and doctors to view ECG data and attenuation coefficients derived from autocorrelation analysis. Data is transmitted between parties using TCP/IP protocol. The system aims to facilitate remote monitoring of cardiac patients to reduce hospitalizations through early detection of health changes.
The document summarizes a polygon oscillating piston engine invention. The engine uses multiple pistons arranged around the sides of a polygon within cylinders. As the pistons oscillate, they compress and combust air-fuel mixtures to produce power. This design achieves a very high power-to-weight ratio of up to 2 hp per pound. Engineering analysis and design of a prototype 6-sided engine is presented, showing it can produce 168 hp from a 353 cubic feet per minute air flow at 12,960 rpm. The invention overcomes issues with prior oscillating piston designs by keeping the pistons moving in straight lines within cylinders using conventional piston rings.
More from International Journal of Engineering Inventions www.ijeijournal.com (20)
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELijaia
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
AI for Legal Research with applications, toolsmahaffeycheryld
AI applications in legal research include rapid document analysis, case law review, and statute interpretation. AI-powered tools can sift through vast legal databases to find relevant precedents and citations, enhancing research accuracy and speed. They assist in legal writing by drafting and proofreading documents. Predictive analytics help foresee case outcomes based on historical data, aiding in strategic decision-making. AI also automates routine tasks like contract review and due diligence, freeing up lawyers to focus on complex legal issues. These applications make legal research more efficient, cost-effective, and accessible.
Build the Next Generation of Apps with the Einstein 1 Platform.
Rejoignez Philippe Ozil pour une session de workshops qui vous guidera à travers les détails de la plateforme Einstein 1, l'importance des données pour la création d'applications d'intelligence artificielle et les différents outils et technologies que Salesforce propose pour vous apporter tous les bénéfices de l'IA.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Software Engineering and Project Management - Introduction, Modeling Concepts...Prakhyath Rai
Introduction, Modeling Concepts and Class Modeling: What is Object orientation? What is OO development? OO Themes; Evidence for usefulness of OO development; OO modeling history. Modeling
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VARIABLE FREQUENCY DRIVE. VFDs are widely used in industrial applications for...PIMR BHOPAL
Variable frequency drive .A Variable Frequency Drive (VFD) is an electronic device used to control the speed and torque of an electric motor by varying the frequency and voltage of its power supply. VFDs are widely used in industrial applications for motor control, providing significant energy savings and precise motor operation.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Finite Element Analysis of Concrete Filled Steel Tube (CFT’s) Subjected to Flexure
1. International Journal of Engineering Inventions
e-ISSN: 2278-7461, p-ISSN: 2319-6491
Volume 3, Issue 12 (July 2014) PP: 18-28
www.ijeijournal.com Page | 18
Finite Element Analysis of Concrete Filled Steel Tube (CFT’s)
Subjected to Flexure
Vijay laxmi B. V.1
, Manoj Kumar Chitawadagi2
1
corresponding Author: Asst. Prof (Civil Engineering), College Of Kls’s Vdrit, Haliyal-581329,
Karnataka State, India
2
prof of Civil Engineering, Bvbcet, Hubli-580031, Karnataka State, India
Abstract: This paper presents a study on flexural behaviour of concrete filled steel tube based on the former
work carried out by Manojkumar. An ANSYS model is developed that can predict the behaviour of concrete
filled steel tube to determine moment carrying capacity at ultimate point for beam Concrete filled steel tube
beams are studied and verified by the finite element program ANSYS against experimental data. The Main
parameters affecting the behaviour and strength of concrete filled beams are geometrical parameters, material
nonlinearities, loading, boundary conditions and degree of concrete confinement. To account for all these
properties ANSYS model is developed. The main parameters varied in analysis study are D/t ratio,
characteristic strength of infilled concrete. The proposed model predicts ultimate moment capacity for CFT
beams. In the numerical analysis, circular and rectangular CFT cross sections are considered using different
grades of concrete. The predicted values are compared with experimental results. Numerical analysis has
shown that for rectangular CFT’s a good confining effect can be provided. Moment capacity results obtained
from the ANSYS model are compared with the values predicted by Lin Han (2004) and different codes such as
AISC-LRFD (1999) and EC4 (1994).
Keywords: Concrete filled steel tubes, beams, circular tubes, rectangular tubes, composite section, ultimate
moment capacity, finite element analysis (FEA) and two-point load.
I. Introduction
Concrete filled steel tube is a composite material which is currently being increasingly used in the
construction of buildings. The use of concrete-filled steel tubular beams in high rise buildings has become
popular in recent years. Concrete filled steel tube beams can provide excellent seismic resistant structural
properties such as high strength, high ductility and large energy absorption capacity. A reasonable
understanding for the behaviour of such columns and beams under earthquake loading is very important. [Hin
Lu et.al ,2009] presented a finite element analysis (FEA) modeling to study the flexural performance of circular
concrete filled thin walled steel tubular beam. The composite action between the steel tube and its concrete core
was analyzed.
In the present era, creation of infrastructure facilities for the development of a country is the most
important task of Civil Engineers. A multistoried building plays a vital role in the development of infrastructure
facilities. In the light of construction of high rise buildings concrete filled steel tubes is one of such an
innovative new building material, which can sustain worst combination of loads, with high stiffness and
facilitating speeder construction and maintaining economy. [Arivalagan and kandasamy, 2010] presented
analytical study on square CFT’s beams using ANSYS and verified with experimental data. Concrete filled steel
tubular structures are one of the modifications to combined load-bearing structures, which are known as
composite or sometimes as complex structures. In addition to the enhancement in structural properties a
considerable amount of time can be reduced due to the prevention of permanent formwork.
[Hu et.al ,2010] conducted a study on proper material constitutive model for CFT’s column of circular
cross section and subjected to pure bending moment was proposed. These material models were implemented
into the FE program and verified against the experimental data. The concrete forms an ideal core to withstand
the compressive loading in the typical applications and it delays and often prevents local buckling of the steel,
particularly in rectangular CFT’s. [Gho and Lu, 2004] presented a study on steel hallow section infilled with
concrete has higher strength and larger stiffness than the conventional structural steel section and reinforced
concrete Additionally, it has been shown that the steel tube confines the concrete core, which increases the
compressive strength for circular CFT’s and the ductility for rectangular CFT’s therefore, it is more
advantageous to use CFT’s. For the columns subjected to the large compressive loading. In contrast to
reinforced columns with transverse reinforcement, the steel tube also prevents spalling of the concrete and
minimizes congestion of reinforcement in the connection region, particularly for seismic design. Elchalakani
et.al (2001) presented an experimental investigation of flexural behaviour of circular concrete filled steel tube
(D/t=12-110) subjected to large deformation under pure bending. It was found that concrete filling of the steel
2. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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tube enhances strength, ductility and energy absorption for thinner sections. [Han, 2004] proposed a model that
can predict the behaviour of concrete filled hollow structural section.
This paper is an attempt to analyze the flexural performance of CFT’s beam in a detailed way by using
FEA modeling. The commercial FEA package ANSYS is used in the numerical simulation. This investigation
aims to use the FEA modeling to analyze the flexural behaviour, interaction of concrete and steel and load
transfer mechanism in circular and rectangular CFT’s under pure bending. Material models of concrete and
steel, interface model to simulate the concrete and steel interface, element type, mesh, boundary condition and
loading. FEA modeling is then used to investigate the stress strain in steel tube and concrete core and the
interaction of concrete and steel tube in CFT’s subjected to pure bending. Finally the results of experiments are
compared with numerical analyses and proposed FE models are verified against the experimental data obtained
by the author.
II. Experimental reference model.
Design concrete mix’s with characteristic strength of 20, 30 and 40 Mpa using locally available
Portland Pozzolana cement (PPC), crushed granite jelly (12mm down) and river sand were used. Mix designs of
these three grades of concrete are made based on the guidelines of IS 10262-1978. Mix proportions adopted for
the three grades of concrete and 28 days cube strength determined in the laboratory for these mixes are shown in
Table 1 Since the steel tube openings are small in size, in order to ensure proper compaction, a higher degree of
workability (80-100mm) slump was adopted for these concrete mixes. This was accomplished by using silica
fume and a superplasticiser as admixtures. Standard 100mm solid cubes were used to test the compressive
strength of the concrete.
Mild steel tubes, cold-formed with yield strength of 250Mpa and 1000mm long were used in the
investigation. Flexure test specimens were tested in a 200kN capacity loading frame. In the test setup, at each
load point and at the supports of the specimen a set of rollers were placed to allow free rotation. Thus the beam
specimens were tested under a simple support condition. The load was applied along two lines spaced at one
third of the effective span from either support. Linearly varying displacement transducers were placed at mid-
span and at the two loading points. The load was increased gradually until the specimen fails and the
corresponding ultimate moment capacity was calculated. LVDT readings are recorded at appropriate load
increments and the lateral deflection of the middle segment of the test beam subjected to pure bending was
calculated using LVDT data.
If δ1 and δ2 are the deflections under the point loads applied on the test beam. Then net deflection (δn)
of the pure bending segment of the test beam is given by
n = m - (
2
21
)
Table (1): Concrete Mix proportions
Sl.
No
Mix
Designa
tion
Binder(B) Kg/m3
Cement silica
fume
Proportions
B:FA:CA
W/B
ratio
Super plasticizer
(%)
(by wt of binder)
28
compressive
strength
(N/mm2
)
Slump
(mm)
1 M20 370 - 1:1.98:2.51 0.55 1.0 27.8 100
2 M30 390 20 1:1.80:2.28 0.45 2.0 42.0 90
3 M40 410 20 1:1.76:2.16 0.40 2.2 51.0 80
III. Finite Element Method
3.1 Finite Element material model
3.1.1 STEEL TUBE and CONCRETE CORE
In the present analysis, average stress strain curve obtained from material tests were used to model both
steel and concrete core, assuming isotropy of the material. The behavior of the steel tube is simulated by an
elastic perfectly plastic model. The material considered as mild steel possessing yield strength (fy) of 250Mpa,
elastic modulus (E) of 200Gpa and for concrete elastic modulus (E) of 5000√fck. The elastic properties are
completely defined by giving the Young’s Modulus (E) and the Poisson’s ratio (ν). By isotropic hardening rule,
multilinear stress strain curve was used to model steel. The main parameter for the multilinear stress strain curve
is the experimentally measured yield stress (fy), the ultimate stress (fsu) and the ultimate strain (εsu). For steel,
first part of the linear curve represents the elastic part up to the proportional limit stress with measured value of
young modulus, Poisson’s ratio equal to 0.3 and density as 7850kg/mm3
. For concrete the Poisson’s ratio (νc) of
0.2 and density as 2500kg/mm3
3. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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3.1.2 Element, mesh, contact between steel and concrete, boundary condition
The choice of the element type and mesh size that provide consistent results with less computational
time is also important in simulating structures with interface elements. Use of fine mesh size provides accurate
results. Type of element for steel tube and concrete is selected from element library in ANSYS. Based on the
geometric characteristics of concrete and steel an appropriate element type for the analysis is selected. Beam
188 type element is chosen for concrete and steel. A fine mesh of 3D quadratic BEAM 188 element was used
for concrete and steel. Surface to surface contact technique was used to model the interaction between the outer
surface of the concrete and the inner surface of the hollow steel tube. The CFT beam is analyzed as full model.
The boundary conditions applied for the nodes lying on the planes of symmetry. Beams are supported by rollers.
The right surface of beam is supported with v=0 but allowing displacement to take place in u and z direction.
The left portion of the beam is symmetry along z direction. The load application on the concrete filled
steel tubes for beam is based on the test arrangement and modeled as point load at node. All models are
generated with a total vertical load of -10kN. An incremental load magnitude along Y direction is applied using
NEWTON RAPHSON method available in ANSYS library. Each incremental of step in the analysis a small
amount of the load is applied until the total magnitude of applied load is reached.
3.2 Basic steps involved in ANSYS
(1) Preprocessing: The major steps in preprocessing are (i) define key points/lines/areas/volumes (ii) Define
element type and material/geometric properties and (iii) mesh Lines/areas/ volumes as required. The amount of
detail required will depend on the dimensionality of the analysis i.e. 1D, 2D, ax symmetric and 3D (iv) To
define contact pairing between the two surfaces if necessary (v) To define constraints (Translational and
rotational) (vi) to define loads (point or pressure).
(2) Solver (solution): Here the analysis type is defined like static, transient depending on model we are
analyzing. Next step is to set the solution using Solution Controls. Finally solving by incremental method using
Newton Raphson solver.
(3) Post processing: In this step we can view the results (i) lists of nodal displacements (ii) element forces and
moments (iii) deformed shape and (iv) stress contour diagrams.
3.3 Methodology adopted
Finite element method has been extensively used to study the structural behaviour of steel concrete
composite section. Finite element model is developed using ANSYS 10 version.
The strength of CFT depends upon the material properties like characteristic strength of infill concrete
Young’s Modulus (E), Poisson’s ratio (ν) and stress/stain values. Geometric properties like wall thickness
(t), diameter (D) for circular, length (l), width (b), depth(d) for rectangular. Therefore, the material and
geometric properties are taken as input parameters for modeling in ANSYS and experimentally obtained
moment capacity (MExpt) is the output parameter
The circular and rectangular CFT’s models are developed by varying geometric properties using element
BEAM 188. Material properties of concrete and steel are used to develop the model.
Using BEAM188 element and material properties meshed model is developed and Boundary condition on
right and left side of CFT beam is applied by constrained along y direction i.e. v=0. The loading on CFT
beam is applied at 1/3rd
span from right support in y direction.
By Incrementing the load using Newton Raphson solver available in ANSYS, Model is analyzed and
ultimate moment, deflection values, specific stresses and strain, bending pattern results are obtained from
Finite element model.
IV. Results and Discussion
Fig (1): Flexure test on CFT beam
4. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Verification of finite element model is an important step in an analytical study. To verify the accuracy
and validity of the finite element model, the model is verified by simulating a number of experimental results.
The numerical results obtained from material and geometric nonlinear static analyses are compared with the
experimental results of the CFT. The comparison of moment carrying capacity between the test results and finite
element model results are presented herein. The experimental results consist of different diameter, length, depth,
wall thickness, strength of infill concrete of CFT. The main parameters varied in the test were thickness of steel
tube, characteristic strength of in-filled concrete, cross sectional size of the steel tube. The ultimate moment
capacity for different geometric property and infill concrete are computed using finite element analysis program.
To verify the model experimental results [Manojkumar, 2009] are considered here in and comparison is made
between experimental results with results obtained by finite element model.
4.1 Prediction of Moment capacity for circular CFT’s beam
Fig1 (a): circular CFT beam with mesh
Fig1 (b): Boundary condition with loading for circular CFT beam
6. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Table1 (b): Comparison of the prediction of ANSYS results and experimental moment capacity results
for circular CFT beam
It is observed that prediction by finite element method is consistent.
Fig1 (e): MExpt v/s MFEM for circular CFT beam under flexure
4.2 Prediction of Moment capacity for Rectangular CFT beam
Fig2(a): Rectangular CFT beam with Mesh
Sl.No MExpt
[7]
(kNm) MFEM(kNm) MExpt/MFEM
1 1.04 1.07 0.97
2 2.33 2.35 0.99
3 2.18 2.11 1.03
4 2.93 2.84 1.03
5 1.34 1.31 0.99
6 2.10 2.04 1.03
7 1.95 1.90 1.02
8 1.65 1.67 0.98
MEAN 1.00
SD 0.03
COV 3.00
7. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Fig2 (b): Boundary condition with loading for rectangular CFT beam
Fig2(c): Deformed shape of rectangular CFT beam beyond ultimate load
Fig2 (d): Bending moment diagram for rectangular CFT beam
8. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Table2 (a): Typical Input and output data for ANSYS validation (rectangular)
Table2 (b): Comparison of the prediction of ANSYS results and experimental moment capacity results
for rectangular CFT beam
Sl.No MExpt
[7]
(kNm) MFEM(kNm) MExpt/MFEM
1 1.27 1.30 0.98
2 1.87 1.80 1.03
3 2.70 2.77 0.97
4 3.76 3.73 1.01
5 5.95 5.96 0.99
6 4.14 4.09 1.01
7 1.95 1.90 1.02
8 5.20 5.18 1.00
MEAN 1.00
SD 0.02
COV 2.00
It is observed that prediction by finite element method is consistent.
Fig2 (e): MExpt v/s MFEM for rectangular CFT beam under flexure
4.3 Confinement of concrete
Concrete inside the steel tube is confined and the strength of such confined concrete depends upon its
own characteristic strength and the thickness of the steel tube. The confinement factor ξ and flexural strength
Index γ (FSI) proposed by Lin-Hai Han [2] are used to explain the effect of confinement.
Sl.No
Input parameters
Moment
Capacity
Area
A(mm2
)
Thickness
t (mm)
Length
(mm)
Cube
Strength
fck(N/mm2
)
MExpt
[7]
(kNm)
1 1250 2 1000 20 1.271
2 1250 1.65 1000 30 1.874
3 2400 2 1000 40 2.706
4 3200 1.6 1000 20 3.762
5 3200 2.65 1000 40 5.951
6 2400 2.65 1000 30 4.14
7 1250 1.65 1000 40 1.951
8 3200 2.65 1000 30 5.196
9. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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=
fckAc
fsyAs
(1)
where As and Ac are the cross sectional area of the steel and concrete core, fy and fck are the yield stress of the
steel and characteristic compressive strength of concrete.
=
fscyWscm
Mu
(2)
Where Wscm = section modulus of the composite beam, given by BD2
/6 and B2
D/6 about major (x-x) and minor
(y-y) axes respectively for composite beams with rectangular section and ПD3
/32 for circular section; Mu=
Moment capacity of the composite beams; fscy=Nominal yielding strength, of the composite sections and
flexural strength index, is given by
For concrete filled steel CHS beams
fscy = (1.14+1.02ξ). fck (3)
γm =1.1+0.48ln (ξ + 0.1) (4)
For concrete filled steel SHS and RHS beams
fscy = (1.18+ 0.85ξ). fck (5)
γm =1.04 + 0.48ln (ξ + 0.1) (6)
FSI is a measure of moment capacity of a given section with given geometric and material strength properties.
FSI increases with increase in confinement factor up to a certain extant and this indicates that better confinement
leads to higher FSI. Hence CFT samples with higher grades of infill concrete have performed better only when
the wall thickness of the steel tube is also correspondingly increased with increase in the confinement factor. A
decrease in the FSI beyond a certain limit indicates that a increase in the wall thickness of the steel tube
combined with a lower strength of infill concrete has no beneficial effect on moment capacity of the CFT
sections.
4.4 Comparison of ANSYS results with test results, Lin-Han, EC4 and AISE-LRFD.
The moment capacity of the CFT beams are calculated based on the specification in the EC4 1994. The
safety factors in the specification were set to unity so that the prediction values obtained in the codes could be
used for the comparison with the experimental ultimate moments. [Table3 a and b] It is observed that EC4
(1994) conservatively predicts the moment capacity of CFT sections used in the present FEM analysis results.
AISC-LRFD provisions do not consider the effect of the infill concrete and hence the predicted moment
capacity values of the CFT samples are again much lower as compared to the experimental results. [Table3 a
and b]
Table 3(a): Comparison of moment capacity results obtained by ANSYS model (MFEM) with experimental
data, Lin Han model (2004) and different codes for circular CFT’s
Sl.
No
D
(mm)
t
(mm)
fck
(N/mm2
)
M(LinHan)
(kNm)
M(EC4)
(kNm)
M(AISC-LRFD)
(kNm)
M(Expt)
[7]
(kNm)
M(FEM)
(kNm)
1 44.45 1.25 40 0.684 0.699 0.583 1.04 1.02
2 44.45 2.00 40 1.071 1.031 0.902 1.34 1.36
3 57.15 1.25 40 1.169 1.2 0.977 1.65 1.62
4 63.5 1.25 30 1.384 1.467 1.211 1.95 1.90
5 57.15 1.60 40 1.448 1.48 1.235 2.10 1.97
6 63.5 1.60 20 1.631 1.743 1.521 2.18 2.17
7 57.15 2.00 30 1.712 1.752 1.533 2.33 2.30
8 63.5 2.00 40 2.210 2.241 1.892 2.93 2.79
Mean 1.300 1.339 1.137 1.799 1.763
10. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Fig 3(a): Comparison of predicted moment capacity results of ANSYS, Lin Han model (2004), EC4 (1994),
AISC-LRFD (1999) with experimental data for circular CFT’s
Table 3(b): Comparison of moment capacity results obtained by ANSYS model with experimental data,
Lin Han model (2004) and different codes for rectangular CFT’s
Sl.
No
Area
(mm2
)
t
(mm)
fck
(N/mm2
)
M(LinHan)
(kNm)
M(EC4)
(kNm)
M(AISC-LRFD)
(kNm)
M(Expt)
[7]
(kNm)
M(FEM)
(kNm)
1 1250 2 20 2.256 1.221 1.129 1.27 1.23
2 1250 2.65 30 3.219 1.567 1.446 1.87 1.91
3 1250 2.65 40 3.24 1.598 1.446 1.95 1.94
4 2400 2 40 4.077 2.272 1.944 2.70 2.64
5 3200 1.6 20 4.333 2.79 2.434 3.76 3.82
6 2400 2.65 30 5.278 2.806 2.511 4.14 4.12
7 3200 2.65 30 7.559 4.419 3.898 5.20 5.24
8 3200 2.65 40 7.795 4.534 3.898 5.95 5.89
Mean 4.280 2.382 2.115 2.984 2.986
+
Fig 3(b): Comparison of predicted moment capacity results of ANSYS, Lin Han model (2004), EC4 (1994),
AISC-LRFD (1999) with experimental data for rectangular CFT’s
11. Finite Element Analysis Of Concrete Filled Steel Tube (Cft’s) Subjected To Flexure
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Moment capacities of all the test samples are determined by the theoretical models proposed byLin-Hai
Han [2]. The model estimates quite satisfactorily the moment capacity of CFT samples tested here in, even
though they have diameters in the range of 44.45-63.5 mm. The estimates are within the experimental values
and it is found that the predicted estimates are much too conservative as compared to actual moments. [Table 3 a
and b]
V. Conclusion
An accurate finite element model for the analysis of concrete filled steel tube beams are estimated
using stress stain curves for steel tube and concrete. From the finite element analysis carried out for CFT beams
following conclusions are drawn
1. It is found that finite element model predicts moment capacity at ultimate point for circular, rectangular
CFT’s quite agree with those determined from actual experiments.
2. Coefficient of variance (COV) between results predicted from finite element model with that of
experimental results for Circular 3.00 and rectangular is 2.00 hence, the predicted value moment capacities
for circular and rectangular cross sections found to give good results without conducting experiments.
3. It can be concluded that the numerical values predicted by FEM for rectangular show better results
compared to circular CFT beams.
4. To verify the accuracy of predicted model large experimental data may be used. Such finite element models
save the cost and time of experimentation to compute moment capacity of circular, rectangular CFT’s.
5. The percentage of error for moment capacity of CFT beams predicted using ANSYS, EC4 (1994), Lin Han
formula (2004) and AISC-LRFD (1999) for circular section are 2.00, 25.56, 27.74, 36.77% respectively; for
rectangular section are 0.048, 20.19, 43.43, 29.11% respectively. This concluded that ANSYS results for
circular, rectangular have less percentage of error. Thus, it can be used to get better results without
conducting experiments.
REFERENCES
[1.] M. Elchalakani, X. L. Zhao and R. H. Grzebieta, “Concrete-filled circular steel tubes subjected to pure bending”, Journal of
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[2.] Lin-Hai Han, “Flexural behaviour of concrete-filled steel tubes”, Journal of Constructional Steel Research Vol 60 (Feb 2004) Issue
2, pp 313-337.
[3.] Wie –Min Gho and Dalin Liu, “Flexural behaviour of high strength rectangular concrete filled steel hollow sections”, Journal of
Construction Steel Research vol.60 (2004), pp 681-1691.
[4.] Lin-Hai Han, Hui Lu, Guo-Huang Yao, Fei-Yu Liao, “Further study on the flexural behaviour of concrete-filled steel tubes”,
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[5.] Soundararajan Arivalagan and Shanmugasundaram Kandasamy, “Flexural behaviour of concrete-filled steel hollow sections
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