# Design of slender columns as per IS 456-2000

Assistant Professor at PSG College of Technology à PSG College of Technology
7 Feb 2018
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### Design of slender columns as per IS 456-2000

• 1. by S.Praveenkumar Assistant Professor Department of Civil Engineering PSG College of Technology Coimbatore Design of Slender Columns
• 3.  The design of a slender column can be carried out by followingThe design of a slender column can be carried out by following simplified methodssimplified methods 1) The Strength Reduction Coefficient method1) The Strength Reduction Coefficient method 2) The Additional moment Method2) The Additional moment Method 3) The Moment Magnification Method3) The Moment Magnification Method The reduction coefficient method, given by IS 456-2000 isThe reduction coefficient method, given by IS 456-2000 is recommended for working stress design for service load and is basedrecommended for working stress design for service load and is based on allowable stresses in steel and concrete.on allowable stresses in steel and concrete. The additional moment method is recommended by Indian and BritishThe additional moment method is recommended by Indian and British codes.codes. The ACI Code recommends the use of moment magnification method.The ACI Code recommends the use of moment magnification method. 3 Methods of Design of Slender ColumnsMethods of Design of Slender Columns
• 4. 4 Page no:71,72-IS 456-2000
• 5. Determination of Total MomentDetermination of Total Moment 5
• 6. 6
• 7. Bending of columns in framesBending of columns in frames 7 (a) Braced (b) unbraced
• 8. Procedure for Design of Slender ColumnProcedure for Design of Slender Column Step-1-Step-1- Determine the Effective Length and Slenderness Ratio in eachDetermine the Effective Length and Slenderness Ratio in each directiondirection Step-2-Step-2- (a) Determine Initial Moment (M(a) Determine Initial Moment (Muiui) from given primary end) from given primary end moments Mmoments Mu1u1 and Mand Mu2u2 in each direction.in each direction. (b) Calculate e(b) Calculate eminmin and Mand Mu,minu,min in each direction.in each direction. (c) Compare moments computed in steps (a) and (b) above and take the(c) Compare moments computed in steps (a) and (b) above and take the greater one of the two as initial moment Mgreater one of the two as initial moment Muiui ,in each direction.,in each direction. Step-3-Step-3- (a) Compute additional moment (M(a) Compute additional moment (Maa) in each direction, using) in each direction, using equationequation 8
• 9. (b) Compute total moment (M(b) Compute total moment (Mutut ) in each direction from using equation) in each direction from using equation without considering reduction factor (kwithout considering reduction factor (kaa)) (c) Make Preliminary design for P(c) Make Preliminary design for Puu and Mand Mutut and find area of steel. Thus p isand find area of steel. Thus p is known.known. Step-4-Step-4- (a) Obtain P(a) Obtain Puzuz. Also obtain P. Also obtain Pbb in each direction, for reinforcementin each direction, for reinforcement ration p determined above.ration p determined above. (b) Determine the value of k(b) Determine the value of kaa in each direction.in each direction. (c) Determine the Modified design value of moment in each direction(c) Determine the Modified design value of moment in each direction MMutut = M= Muiui + k+ kaa MMaa 9