Short Composite Columns - thesis
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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.
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Short Composite Columns - thesis
- 1. BEHAVIOUR OF CONCRETE ENCASED BUILT-UP STEEL CONCRETE COMPOSITE COLUMNS WITH ANGLE SECTIONS By S.Amudhalingam (0271101) Under the guidance of Tmt.V.M.Shanthi Lecturer in Civil Engg (Sel.Grd)
- 2. INTRODUCTION COMPOSITE COLUMNS EXPERIMENTAL PROGRAMME ANALYTICAL PROGRAMME RESULTS GRAPHS CONCLUSIONS BIBLIOGRAPHY PRESENTATION OUTLAY
- 3. General SteelSteel and concreteand concrete Concrete is efficient in compression and steelConcrete is efficient in compression and steel in tensionin tension Concrete encasement restrain steel against bucklingConcrete encasement restrain steel against buckling Protection against corrosion and fireProtection against corrosion and fire Steel bring ductility into the structureSteel bring ductility into the structure
- 4. COMPOSITE COLUMNS Definition Composite columns are compressive members in which steel section acts compositely with concrete. So that, both steel and concrete resist the compressive force.
- 5. abc bcy y z tf h hc cz b y z h = hc b = bc d c y z b y z t t h b e d t y z f d t y z cy cz tw tf tw tw h = hc b = bc tf TYPES OF COMPOSITE COLUMNS
- 6. OBJECTIVE OF THE PROJECT To study the behaviour of built-up steel concrete composite columns with angle sections under axial load and Uniaxial bending (two eccentricities) To study the effect of Fibre reinforced concrete and Additional reinforcement. To find the moment interaction curves for the built-up sections for ANGLE sections.
- 7. TYPES OF SECTIONS Types of specimens Dimensions of the sections Height of the specimens Types of Variation Built up Angle sections 20×20×3 mm (3 nos) 890mm Angle sections with Conventional concrete Built up angle Sections 20×20×3 mm (4 nos) 890 mm Angle sections with Fibre reinforced concrete Built up Angle sections 20×20×3 mm (4 nos) 890 mm Angle sections with Additional reinforcement
- 8. BUILT UP ANGLE SECTION WITH SINGLE LACING
- 9. EXPERIMENTAL PROGRAMME MATERIAL PROPERTIES Cement _ Ordinary Portland Cement (43 grade) Fine Aggregate – Passing through 4.75 mm sieve Coarse Aggregate – 6 mm Water – Potable Water Steel – Cold rolled Steel Sections of 3mm thickness MIX DESIGN - IS METHOD 1 : 1.67 : 2.71 : 0.45
- 11. ANALYTICAL PROCEDURE PLASTIC RESISTANCE OF THE ENCASED SECTIONS Pp =Aa fy /γa +αc Ac fck / γc Aa, Ac = Area of steel and concrete fy = Yield strength of steel fck = characteristic compressive strength of cube αc =strength coefficient
- 12. MAXIMUM MOMENT OF RESISTANCE OF THE SECTION Mmax = PyZpa +0.5PckZpc Py = Yield strength of steel Pck = characteristic strength of concrete Zpa,Zpc = plastic section modulus for steel and concrete section
- 13. ANGLE SECTION Sl. no Types of loading First crack load in KN Maximum load in KN T/E % of increase Maximum deflection in mm T/E Position Theoretic al Experimen tal Theoret ical Experi mental 1 Axial 360 406 718 0.565 12.91 1.64 1.78 0.91 L/2 2 Eccentricity @15mm 320 406 584 0.695 18.5 1.82 1.96 0.89 L/2 3 Eccentricity @20 mm 370 372 430 0.84 0.6 2.02 1.99 0.96 L/2
- 14. ANGLE SECTION WITH REINFORCEMENT Sl. no Types of loading First crack load in KN Maximum load in KN T/E % of increase Maximum deflection in mm T/E Position Theoretic al Experimen tal Theoret ical Experi mental 1 Axial 480 435 758 0.574 42.6 2.24 2.36 0.92 L/2 2 Eccentricity @15mm 640 354 656 0.539 46.1 2.59 2.89 0.86 L/2 3 Eccentricity @20 mm 446 435 647 0.672 32.8 2.86 3.04 0.79 L/2
- 15. ANGLE SECTION WITH FIBRE REINFORCED CONCRETE Sl. no Types of loading First crack load in KN Maximum load in KN T/E % of increas e Maximum deflection in mm T/E Positio n Theoreti cal Experimen tal Theore tical Experi mental 1 Axial 618 376.72 694 0.5428 45.72 2.82 3.12 0.79 L/2 2 Eccentricity @15mm 430 376.72 543 0.693 31.7 3.14 3.32 0.74 L/2 3 Eccentricity @20 mm 526 376.72 532 0.708 29.2 3.35 3.64 0.71 L/2
- 16. RESULTS AND DISCUSSIONS Load Deflection graph for angle section under axial load 0 50 100 150 200 250 300 350 400 450 0 0.1 0.2 0.3 0.4 0.5 0.6 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction l/4 y direction l/2 y direction 3l/4 y direction
- 17. Load deflection graph for Angle section under e - 15mm 0 10 20 30 40 50 60 70 80 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 Delfection in mm LoadinKN l/4 x 3l/4 x l/2 x
- 18. Load and Deflection of angle section with 20mm eccentricity 0 50 100 150 200 250 300 350 400 0 0.5 1 1.5 2 2.5 3 Deflection in mm Loadinmm l/4 x direction l/2 x direction 3l/4 x direction
- 19. Load deflectiongraph for angle section with additional reinforcement under axial load 0 100 200 300 400 500 600 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction l/2 y direction
- 20. Load - Deflection for angle-sectionwith additional reinforcement under 15 mm eccentricity 0 50 100 150 200 250 300 350 400 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 direction
- 21. Load - Deflection graph for angle section with additional reinforcement under 20 mm eccentricity 0 100 200 300 400 500 600 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction
- 22. Load - deflection graph for fibre reinforced angle section under axial load 0 100 200 300 400 500 600 700 0 0.5 1 1.5 2 2.5 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction l/2 y direction
- 23. Load - deflection for fibre reinforced angle section under 15 mm eccentricity 0 100 200 300 400 500 600 0 0.5 1 1.5 2 2.5 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction
- 24. Load - deflection for fibre reinforced angle section under 20 mm eccentricity 0 50 100 150 200 250 300 350 400 450 500 0 0.5 1 1.5 2 2.5 3 Deflection in mm LoadinKN l/4 x direction l/2 x direction 3l/4 x direction
- 25. Moment curvature for Angle section with Fibre reinforced concrete under e-15mm 0 1 2 3 4 5 6 7 0.000000 0.000001 0.000002 0.000003 0.000004 0.000005 Curvature in Radians MomentinKN.m
- 26. Moment curvature of Angle section with Fibre reinfroced Concrete under e-20mm 0 2 4 6 8 10 12 0.000000 0.000020 0.000040 0.000060 0.000080 0.000100 0.000120 Curvature in radians MomentinKN.m
- 27. Moment curvature for Angle section with reinforcement under e-15mm loading 0 1 2 3 4 5 6 0.000000 0.000002 0.000004 0.000006 0.000008 0.000010 0.000012 0.000014 0.000016 Curvature in radians MomentinKN.m
- 28. Moment Curvature diagram for Angle section with reinforcement under e-20mm 0 1 2 3 4 5 6 7 8 9 0.000000 0.000010 0.000020 0.000030 0.000040 0.000050 0.000060 0.000070 0.000080 0.000090 0.000100 Curvature in radians MomentinKN.m
- 29. Moment curvature for Angel section with 15 mm eccentricity 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.000000 0.000002 0.000004 0.000006 0.000008 0.000010 0.000012 0.000014 Curvature in radians MomentinKN.m
- 30. Moment curvature for Angle section with e-20mm 0 1 2 3 4 5 6 7 8 0.000000 0.000020 0.000040 0.000060 0.000080 0.000100 0.000120 Curvature in radians MomentinKN.m
- 31. C o mp a r i s o n o f M a x . D e f l e c t i o n f o r v a r i o us s p e c i me n s 0 100 200 300 400 500 600 0 0. 5 1 1. 5 2 2. 5 3 D e f l e c t i o n i n m m A ngl e under ax i al l oad A ngl e under e-15 mm A ngl e under 20 mm A ngl e r ei nf or c ed under ax i al l oad A ngl e r ei nf or c ed under e-15mm A ngl e r ei nf or c ed under e- 20mm Fi br e angl e s ec t i on under ax i al Fi br e angl e under e-15mm Fi br e angl e under e-20mm
- 32. LOAD MOMENT INTERACTION DIAGRAM FOR ANGLE SECTION 0 50 100 150 200 250 300 350 400 0 1 2 3 4 5 6 MOMENT IN kN-M LOADINkN C D B A Mpl Mmax Pp Pc 0.5Pc M P
- 33. CONCLUSIONS Steel elements are not yielding throughout the complete loading condition. Instead, concrete material failure occurred at a load level close to the maximum axial load. Failure occurred by crushing of the concrete at the compression face of the cross section. The maximum load was attained without any distortion of the built-up section or slip between steel and concrete elements.
- 34. The composite column will take more loads and the bare steel skeleton will fail by elastic instability at lower load value. The concrete can be relied upon to transfer the shear between the steel element and concrete. Experimental load carrying capacity is more than the theoretical load carrying capacity . when eccentricity is more, variation in the prediction of load carrying capacity is more. When eccentricity is less, variation is also less. This concludes that the theoretical is conservative
- 35. The deflections obtained experimentally compared satisfactorily with theoretical values. Theoretical solution slightly underestimated the value of the collapse load. No significant torsional displacement could be detected at mid height of the column. Among all the specimens, built-up angle section with fibre reinforced concrete is found to take more load.
- 36. SCOPE OF THE FUTURE STUDY Experimental study on behavior of composite column with different cross-sections can be carried out. In this thesis work, baby chips were used as coarse aggregate. Study can be done by varying sizes of coarse aggregate. The study can be extended to slender composite columns. The effect of shear connectors can be studied for future work. Using cold formed and hot rolled steel sections, various other shapes can be carried out and tested.
- 37. REFERENCES Furlong R.W. “Strength of steel encased concrete beam-columns”, Journal of Structural Division, ASCE,1967:93(ST5):pp 115- 130. N.E.Shanmugam,B.Lakshmi “State- of – art – report on composite columns”, Journal of Constructional Steel Research. Munoz , “Biaxially loaded concrete-encased composite columns”, Journal of Structural engineering,ASCE,1997,pp1576- 1585. www.fb-embureyplus.com
- 38. Thank you!!!