Reinforcement detailing of Columns from ETABS output

PROJECT:- Reinforcement detailing of Columns from ETABS output

INTRODUCTION:-

The reinforcement detailing of columns consist of carrying out the design of two columns, 3A & 3B for longitudinal and shear reinforcement.

Shear reinforcement design of columns:

Shear reinforcement demand on columns is larger of,

• factored shear force demand as per linear structural analysis, and
• factored equilibrium shear force demand when plastic hinges are formed at ends of the beams given by:
• 

Longitudinal reinforcement on columns:-

• Circular column should have a minimum of 6 bars
• Rectangular columns must have a minimum of 8 bars (4 at corners and 4 at mid length)
• As per IS456-2000(design code for RCC structures), the minimum c/s area of lomgitudinal steel is 0.8% of gross cross sectional area of column.
• Bars should not be less than 12mm in diameter.

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 the challange 7 attachment which are provided to us
• After downloading open the Challenge open it in the Etabs 20 software

• Select the 3A and 3B columns from all stories as shown a in below;

• Change the view into Elevation view - 3
• And Run the Analysis

• Now we have to start the column design by selecting the "concrete frame design" an below showing;

• Below showing longitudinal reinforcement of the columns 3A and 3B after run the analysis

• Now we are separately showing longitudinal reinforcement and shear reinforcement of the columns

Longitudinal reinforcement and shear reinforcement and Diagramatical details of the column at grid 3A from ETABS;

1. Longitudinal reinforcement:-

2. Shear reinforcement:-

NOW WE HAVE TO PROVIDE DEATIL REINFORCE,MENT TO THE COLUMN;

1. For GRID 3A -

From Base to first floor the maximum Ast is = 7027mm2

So we can provide 8 no's of 32 mm diameter bar = 8 x 803.84

= 6430.72 mm2

also we can provide 2 no's of 20 mm diameter bar = 2 * 314

= 628 mm2

8 no's of 32 mm+2 no's of 20 mm = 6430.72+628

=7058.72 mm2>7027mm2 ........hence okay

Diagramatical Details of column at grid 3A are shown below -

Longitudinal reinforcement and shear reinforcement and Diagramatical details of the column at grid 3B from ETABS;

1. Longitudinal reinforcement:-

2. Shear reinforcement:-

2) For GRID 3B -

From Base to Terrace floor the maximum Ast = 5046 mm2

So , Provide 8 bars of 25 mm diameter for the column = 8 x 490.87*8

= 3927mm2

Provide 2 bars of 32 mm diameter for the column = 4 x 314.16

= 1607.68mm2

Therefore;

Provide 8 bars of 25 mm diameter for the column + Provide 4 bars of 20 mm diameter for the column =

= 3927 + 1607.68

= 5534 mm2>5046 ...........hence okay

Diagramatical Details of 3B Grid are shown below ;

Now ,Typical Beam column Joint as per special confining reinforcement provision of clause 8.1 of IS 13920 -2016

As per IS 13920 - 2016 at beam column junction:-

• For beam - The spacing from the face of the beam should not be more than 100 mm till 2d
• For Column - The spacing from the face of the column will be lo and should not be more than Least lateral dimension, (1/6)th of clear span or 450 mm

RESULT:-

• The given Etabs model has been analysed after checking the model.
• Then concrete frame design has also been carried out hence the reinforcement area required has been obtained.
• The longitudinal reinforcement details obtained from the results have been drafted in AutoCAD software.
• Similarly the shear reinforcement detiakls also have been drafted.