Design of concrete structure.
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This presentation summarizes information about reinforced concrete columns. It was presented by a group of 9 students from the Department of Civil Engineering at Dhaka University of Engineering & Technology to faculty members. The presentation defines columns, classifies columns based on shape, reinforcement, and loading, and describes the effective length, buckling modes, sizing, reinforcement, cover, lapping, hoop reinforcement, and failure modes of columns. The objectives are to understand column arrangement, design specifications, and characteristics.
Design of concrete structure.
- 2. Course No. : CE-2106 Credit : 0.75 Course Title : Design of Concrete Structures-I (Sessional) Topic : Reinforced Concrete Column
- 3. Presented by : Group : B 1-1 Department of Civil Engineering Dhaka University of Engineering & Technology, Gazipur. Md. Mehedi Hasan - 161065 Md. Tayeb Hasan - 161066 Md. Momin Ali - 161067 Md. Rabeul Awal - 161068 Md. Mehedi Hasan Shamim - 161069 Md. Helal Sarker - 161071 M M Alamgir Hossain - 161072 Faysal Ahmed - 161073 Md. Morshed Alam - 161074
- 4. Presented to : Department of Civil Engineering Dhaka University of Engineering & Technology, Gazipur. Dr. Md. Khasro Miah Professor Department of Civil Engineering Suman Mia Assistant Professor Department of Civil Engineering Md. Tarek Hasan Lecturer Department of Civil Engineering
- 5. Objectives ❑ To know the arrangement of RCC Column. ❑ To know about design specification . ❑ To know about the characteristic of Column .
- 6. ★ Definition of column (BNBC-6.3.2.1) : A primarily compression member, which may or may not be designed to carry simultaneous flexural forces, shall be termed a column. ● Normally columns carry heavy compressive loads. ● Columns are used in concrete and steel buildings. What is column ?
- 8. CLASSIFICATION (On The Basis of Shape) 1. Square Section 2. Rectangular Section 3. Circular Section 4. T Section 5. L Section
- 9. CLASSIFICATION (On The Basis of Reinforcement) Tied Spiral Composite Combination
- 10. Concentrically Loaded Eccentrically Loaded 1. Concentrically Loaded Column -resultant load acting in center 2. Eccentrically Loaded Column- resultant load does not acting in center I. Uniaxial column - acting one axis II. Biaxial column - acting both axis CLASSIFICATION (On The Basis of Load) BiaxialUniaxial
- 11. EFFECTIVE LENGTH OF COLUMN Effective length of column is defined as height between the point of contraflexure of the buckled i.e. between two floors basically. No. End condition of column Effective length 01. Both ends pin ended 1.O L 02. Both ends fixed 0.5 L 03. One end fixed and the other end pinned 0.707 L 04. One end fixed and the other end free 2.0 L
- 12. BUCKLED MODE FOR DIFFERENT END CONNECTIONS
- 13. BNBC Code 8.3.5.1 specifies : ❑ Tied column: minimum size-12 inch or 300 mm ❑ Spiral Column: minimum size of dia-12 inch or 300 mm ❑ The ratio of the shortest cross-sectional dimension to the perpendicular dimension shall not be less than 0.4 SIZE OF COLUMN
- 14. Function of longitudinal bar in column • To resist any tension that might develop due to bending caused by transverse load, eccentric load of the moments. • To reduce the effect of creep and shrinkage due to sustained loading. • To prevent or delay sudden collapse.
- 15. MINIMUM LONGITUDINAL BARS OF COLUMN (According to BNBC – 6.3.6.3) 1.Minimum of 6 bars in circular arrangement enclosed by spiral reinforcement. 2.Minimum of 4 bars in rectangular arrangement enclosed by ties reinforcement. 3.Minimum of 3 bars in triangular arrangement enclosed by ties reinforcement
- 16. Amount of Reinforcement (According to BNBC - 6.3.6.1) 1% to 6% in main bar (According to ACI -10.6.1.1) 1% to 8% in main bar
- 17. MINIMUM SPACING FOR LONGITUDINAL BAR (According to BNBC - 8.1.6.3) ★ 1.5 times of bar diameter or ★ 1.33 times of coarse aggregate size or ★ 25 mm (1 inch) Largest value is used for spacing.
- 18. FUNCTIONS OF TIES ★ To hold the longitudinal bars in position ★ To prevent the highly stressed ★ To prevent buckling
- 19. RULES OF TIE ARRANGEMENT (According to ACI Code:10.7.6.1) Lateral Tie Longitudinal Bar #3 or 10 mm <=32mm #4 or 12 mm >=36mm ★ Maximum 4 bars are used if longitudinal bars are bundled. ★ Lateral ties should not be less than 10mm.
- 20. MINIMUM SPACING FOR TIES (According to ACI Code:25.7.2.1) ★S = 16*dia of longitudinal bar ★S = 48*dia of lateral bar ★S = Least lateral dimension of column smallest value is used for spacing. Minimum spacing for spirals (ACI:25.7.3) ★Pitch = 1.0 inch to 3.0 inch (25mm to 75mm)
- 21. • Covering in contact with earth : 3 in or 75mm. • If shuttering is used, covering in contact with earth : 2.5 in or 62.50mm. • ( According to BNBC- 8.1.7.2 ) • When concrete surface not exposed to weather or in contact with ground the minimum cover is 30 mm to 40 mm or minimum 1 inch MINIMUM COVERING FOR COLUMN
- 22. LAPPING Lapping means overlapping of two bars side by side to. Lapping is usually done where minimum bending stress is encountered. Lapping length = 48*dia of main bar
- 23. HOOP LENGTH & SPACING Web reinforcement provide at support section (using largest value) 1. l0 = L/6 (L= clear height between two floors) 2. l0 = maximum dimension 3. l0 = 18 inch Spacing of tie bar (using smallest value) 1. S = 8*dia of main bar 2. S = 24*dia of tie bar 3. S = 0.5*maximum dimension 4. S = 12 inch
- 24. BUNDLE BAR ( According to BNBC-8.1.6.8 ) ★ Groups of parallel reinforcing bars bundled to act as a single unit shall be limited to four. ★ Bundled bars shall be enclosed within stirrups or ties. ★ Where spacing limitations and minimum concrete cover are based on bar diameter, a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area.
- 25. FAILURE MODE OF COLUMN 1.LONG COLUMN Long columns fail by buckling
- 26. 2.INTERMEDIATE COLUMN • Intermediate columns fail by a combination of crushing and buckling
- 27. 3.SHORT COLUMN • Short columns fail by crushing
- 28. THANK YOU