Column Design Rule As Per ACI Code

Here we will learn some basic knowledge about column design rule as per ACI CODE

STRENGTH OF CONCRETE

Ø Compressive strength of concrete, (𝑓𝑐′)   shall not be less than 17 MPa.
Ø Modulus of elasticity, 𝐸𝑐, for concrete shall be permitted to be taken as Wc〗^1.50.043√𝑓𝑐′ (in MPa) for values of W𝑐 between 1440 and 2560 kg/m3.
Ø For normal weight concrete, 𝐸𝑐 shall be permitted to be taken as 4700√𝑓𝑐′ (in MPa).
 
DESIGN STRENGTH OF REINFORCEMENT
Ø Design strength of reinforcement represented by the values of 𝑓𝑦  used in design calculations shall not exceed 550 MPa .
Ø for transverse reinforcement 𝑓𝑦 may exceed 420 MPa .
Ø Modulus of elasticity, 𝐸𝑠, for reinforcement shall be permitted to be taken as 200,000 MPa.
 
 

STRENGTH REDUCTION FACTOR πœ™

For compression-controlled sections,

Ø Members with spiral reinforcement conforming  Γ  0.75

Ø  Other reinforced members  Γ  0.65

Column Design Rule

LIMITS OF REINFORCEMENT FOR COMPRESSION MEMBERS

Ø The area of longitudinal reinforcement, 𝐴𝑠𝑑, shall be not less than 0.01𝐴𝑔 or more than 0.06𝐴𝑔.

Ø Minimum number of longitudinal bars in compression members shall be ,      

 

  •       4 for bars within rectangular or circular ties
  •        3 for bars within triangular ties
  •         6 for bars enclosed by spirals conforming  
Column Design Rule
Ø MOMENTS OF INERTIA, 𝐼= 0.70𝐼𝑔
ØFor compression members, the clear distance between longitudinal bars shall be not less than

  •          1.5 bar diameters
  •           40 mm (1.5in)
  •       1.33 times of maximum nominal size of coarse aggregate.
Ø Minimum cross-sectional dimension for a Column: is  9″x 12″ (225 MM x 300 MM) which is the minimum recommended size.
Ø Required Reinforcement for a Column: minimum 1% and maximum 8% of Cross sectional area of column.
 
 
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