Reinforcement detailing of Columns from ETABS output

CHALLENGE - 8

ANSWERS

1. AIM & INTRODUCTION:

• To Know the design of RC column using ETAB analysis.
• To know the basics of column reinforcement details with respect to primary standards.
• To ensure the ductility reinforcement required as per IS 13920-2016 has been satisfied in reinforcement drawing.

LONGITUDINAL REINFORCEMENT OF COLUMN AT GRID 3A (mm2)

SHEAR REINFORCEMENT OF COLUMN AT GRID 3A (Cm2/1000mm)

LONGITUDINAL REINFORCEMENT OF COLUMN AT GRID 3B (mm2)

SHEAR REINFORCEMENT OF COLUMN AT GRID 3B (Cm2/1000mm)

SPECIAL CONFINING REINFORCEMENT FROM IS:13920-2016:(Clause 8.1)

L₀ not less than of the following:

1. Larger lateral dimension of column = 650mm
2. 1/6 of the clear span of the member = 3000/6 = 500mm
3. 450mm

Out of 650mm,500 & 450mm, selecting max value as 650mm

Confinement spacing not more than of the following:

a) ¼ of minimum column dimension = 450/4 = 112.5mm

b) 6 times the diameter of smallest longitudinal reinforcement of bars

= 6x25 = 200mm

c) 100mm

Out of 112.50mm,200 & 150mm, selecting min value as 100mm

The amount of confinement rebar:

For rectangular column:

Sv = 100mm

h = (600-2x50+2x10)/3 = 173

Fck = 25 N/mm2

Fy = 500 N/mm2

Ag = 600x450 = 270000 mm2

Ak = 3.14/4 x D² = 3.14/4x 390² = 119399 mm²

Ash = [0.18x100x173x25/500(270000/119399 – 1)]

Amount of confinment reinforcement = 196 mm²

Assume 3 leg ties of 8mm dia bar

i.e Area of 3leg tie is 3 x 50.5 = 151 mm²

Lo is 650 mm and 100mm spacing which comes out to be 6x151 = 906 mm²

Hence 906 > 196 . OK

REINFORCEMENT DETAILS OF COLUMN 3A