Reinforcement detailing of Columns from ETABS output

                                 Reinforcement detailing of Columns from ETABS output

                                                                                                                                         Jagadeep.M.M

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. 

AIM:

      To provide details of longitudnal reinforcement for the two columns from foundation to terrace level.Also              calculate the special confining reinforcement based on clause 8.1 of IS 13920-2016.

PROCEDURE:

• After downloading the model given on the question,open the ETABS software and open the downloaded model.
• Click on view and revise preferences.Check all the design codes are correct or not.
• Analyze and check the model.

 

• Analyse and run analysis,
• Using the above toolpath,the given model is checked for its error and warnings.The model found to be ok.
• Analysis is complete.
• Now click on design preferences and click on ok. 

• Click on design combinations and click on ok.

• Select the column od 3A & 3B.

Now click on the concrete frame design.

3-A 

Select the longitudinal reinforcement & shear reinforcement

• From base to terrace  the maximum Ast=6929 sq.mm
• So we can provide 8 bars of 32mm=8x803.84=6430.72sq.mm
•                            2 bars of 16mm=2x200.96=401.92sq.mm                                                                                                              Total Ast=6832.64sq.mm

 

3-B

Select the longitudinal reinforcement & shear reinforcement

• From base to terrace  the maximum Ast=4942 sq.mm
• So we can provide 7 bars of 28mm= 7x615.44=4308.08 sq.mm
•                             3 bars of 20mm=3x314=942 sq.mm

                                              Total Ast=5250.8sq.mm

Calculation of special confining reinforcement:

 As per clause 8.1 of IS 13920-2016,the special confining reinforcement is calculated:

As per the clause 8.1 section a,the confing reinforcement length lo should be least of

i) larger dimension of frame member(650mm)

ii) 1/6th of clear span(591mm)

iii) 450mm

So maximum of three is 650mm so Lo=650mm.

Maximum spacing of confining reinforcement:

As per clause 8.1 section b the maximum spacing of confining reinforcement shall be:

i) 1/4th of minimum member dimension(112.5mm).

ii) 6 times of smallest longitudnal bar ( 108mm).

iii) 100mm

So maximum shear link spacing maintained=100mm

So minimum special confining reinforcement should be maximum of

Ash= 631 sq.mm/m

Ash= 337 sq.mm/m

Required minimum special confining reinforcement at joint Ash=631 sq.mm

Now provide shear reinforcement at joint = (1000/100)X4 legs Xarea of 8mm dia rebar(50.3 sq.mm)=2010 sq.mm