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. 

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.

PROCEDURE:-

• Open the challange 7 attachment which are provided to us.
• Check model and Run analysis.

• Select the 3A and 3B columns  from all stories as shown a in below.
• Click on concrete frame design to design the frame
• Click on concrete frame design and select display design information

• Below showing longitudinal reinforcement of the columns 3A and 3B.

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

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

 1. For GRID  3A :

•  From Base to first  floor the maximum Ast = 7027 mm2
•  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 x 314

                                                                             = 628 mm2

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

                                                        =7058.72 mm2 >7027 mm2 .Hence okay.

• First Floor

•  Second Floor

•  Third Floor

 RESULT:

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

For GRID  3B :

•  From Base to Terrace floor the maximum $A_{st}$   = 5046 mm2
•  So , Provide 8 bars of 25 mm diameter for the column  = 8 x 490.87 x 8

                                                                                 = 3927 mm2

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

                                                                                 = 1607.68 mm2

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 mm2. Hence okay

• Base to First Slab

•  First Floor

•  Second Floor

•  Third Floor

•  FINAL OUTPUT:

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 and Shear reinforcement details obtained from the results have been drafted in AutoCAD software.