Reinforcement detailing of Columns from ETABS output

AIM:Reinforcement detailing of columns in Etabs 2018.

The ETABS file for a G+4 building is provided. Run the analysis and design the RCC Moment Resisting Frame. The following challenge deals specifically with two columns at the following grid intersections.

1. 3A
2. 3B

• Provide details of longitudinal reinforcement for the two columns, from foundation to terrace level. Sketch the column cross sectional & elevation details or draft it using autocad software.
• Show shear reinforcement & lapping details as per special confining reinforcement provision of clause 8.1 of IS 13920 - 2016.

PROCEDURE:

• open ETABS
• Open the week7 challenge->run the analysis
• Go to eleveation->select the 3 grid section

• go to concrete frame design->show output->longitudnal reinforcement

• we only considering 3A and 3B column
• set display option->uncheck beams (to only show columns)
• select the 3A and 3B column to->right click-> show selected objects

• concrete frame design->show deatil->shear reinforcing

Column 3A

• MAximum Ast of in Grid-3A column is 6938mm^2
• so we can provide 8#-32mm dia bars= 6432mm^2
• and 2#-20mm dia bars= 628mm^2
• so the total Ast steel on longitudnal bars is 7060mm^2 > required Ast

we design the 3A grid column in AutoCAD shown below

• Longer side on the cross section parell to Y Axis and shorter side parellel to X axis
• Ties parellel to X Axis is provided because the distance between the bars exceeds 300mm on longer face
• IS 13920:2016 clause 7.4.2 fig 10B

Bars arrangements shown in section of column 3A

• "L." is special confinement used as per IS13920:2016 clause 8.1
• L.=650mm and 2 legged stirrups of 8mm @ 100mm C/C as per IS13920
• Lap splices is provided at the mid height of columns ;lap length=45*d (d=diameter of biggest longitudnal bar used)
• 45*32mm=1440mm i.e. lap length and stirrups are provided 8mm bars @120mm C/C
• Lap splices as per IS13920 clause 6.2.6.1

Column 3B

• MAximum Ast of in Grid-3B column is 5022mm^2
• so we can provide 4#-32mm dia bars= 3216mm^2 (At each corners)
• and 4#-25mm dia bars= 1960mm^2 (At mid point of each side)
• so the total Ast steel on longitudnal bars is 5176mm^2 > required Ast

• we design the 3B grid column in AutoCAD shown below

• Longer side of the cross section parellel to X Axis and shorter side parellel to Y axis

• Ties parellel to Y Axis is provided because the distance between the longitudnal bars exceeds 300mm on longer face

• IS 13920:2016 clause 7.4.2 fig 10B

Longitudnal reinforcement design of 3B column

• orientation of this column is along X axis
• lap length and special confinement are similar to the 3A column(due to same size of columns)
• 4 longitudnal bars of 32mm dia used at corners
• 4 longitudnal bars of 25mm dia used at the mid of the side faces