Reinforcement detailing of Columns from ETABS output

Aim- To Run the analysis and design the RCC Moment ResistingFrame. The ETABS file for a G+4 building is provided.

Introduction- The ETABS file for a G+4 building is provided.

The following challenge deals specifically with two columns at following grid intersection

1) 3A
2) 3B

Procedure-

-Open attached file in ETABS

-Now Run Analysis

-Select column which intersect at 3A and 3B grid

-Select elevation view along 3

-Now process concrete frame design

-Selct Display design info>Select longitudinal reinforcement>Ok

-Select Display design info>Select shear reinforcement>Ok

-Column Design as per IS13920

width >300mm

>20*20(Largest diameter longitudinal reinforcement in the beam)

Provided width of column= 400m

450mm > 400mm...........O.K.

Clause 7.1.2:

Aspect Ratio:

Width/depth >0.45

450/650 = 0.69

0.69>0.45..................O.K.

IS 456 Clause 26.5.3.1:

Minimum Reinforcement= 0.8%bD

= (0.8*450*650)/100

Ast(min)=2340mm2

Maximmum Reinforcement= 4%bD

= (4*450*650)/100

Ast(max)=11700mm2

Ast(min) < Ast(prov) < Ast(max)

2340mm2<4213mm2<11700mm2

Provide 9 no's 25mm dia bars.

PITCH (SPACING):

IS 456 Clause 26.5.3.1

g) Spacing <300mm

TRANSVERSE REINFORCEMENT:

IS 13920 Clause 7.4.2:

Spacing= min(300mm, least lateral dimension/2)

= min (300mm, 450/2)

= min (300mm,225mm)

Provide 2 legged 10mm dia at 200mm c/c

SPECIAL CONFINING REINFORCEMENT:

Lo not less than-

1. Larger column dimension = 650mm
2. 1/6 of clear span of column = 491mm
3. 450 mm

Provide Lo of 650mm

Confinement spacing not more than-

1. ¼ of smaller column dimension = 450/4 = 112mm
2. 6 times of dia of column main bar= 6*25 = 150mm
3. 100mm

Provide 100mm spacing

Ash = 180mm2

Anchorage Length:

`L_d=(0.87*f_y*d)/(4*tau_(bd)`

= `(0.87⋅415⋅d)/(4⋅(1.6)⋅1.4)`

= 40d

Anchorage Length = Ld +10d -8d

(Allowance for 90 degree bend = 8d)

X =42d

X =42*25

X =1050mm

Result-

• Provided details of longitudinal reinforcement for the two columns (3A and 3B), from foundation to terrace level.

• Shown the column cross sectional & elevation details using AutoCAD software.
• Shown shear reinforcement & lapping details as per special confining reinforcement provision of clause 8.1 of IS 13920 - 2016.