Reinforcement detailing of Columns from ETABS output

Reinforcement detailing of Columns from ETABS output

 

 

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

 

 

Aim: to know how the quantity of steel required in given column section, or details of given two RC beam 

 

Introduction: work on the check satisfaction, its satify the IS with analys values, to ensure the load capacity of member over the load demand 

 

Procedure: 

step 1) 

open the plan provided in challenge 

in etabs 2018 

open first floor plan 

 

step 2)

Analys the structure 

by clicking on run anlyasis tab

we get the maximum and minimum deflection 

 

 

step 3) concrete frame design 

click on concrete frame design button to know the longitudinal and axial reinforcement of all the frames 

like column and beams 

 

 

 

step 4) check shear reinforcement as well

 go to concrete frame option

droup down the button and click on the 

display design frame 

 

step 5) reinforcement detaling on auto cad 

 Longitudnal reinforcement for the two columns from foundation to terrace:

Grid A

From base to terrace  the maximum Ast=6926 sq.mm

So we can provide 8 bars of 32mm=8x803.84=6430.72sq.mm

                           3 bars of 16mm=3x200.96

                                                  =602.88sq.mm

                                         Total Ast=7033.6sq.mm

 

 

 

Grid B

From base to terrace  the maximum Ast=4942 sq.mm

So we can provide 7 bars of 28mm= 7x615.44

3 bars of 20mm=3x314

Total Ast=5250.8sq.mm

 

 

 

 

 

step 6) special confining reinforcement   

As per clause 8.1 of IS13920-2016, the special confining reinforcement is calculated and verified with the drawing detail.

As per cluase 8.1 section a), the confining reinforcement length $l_o$should be at least

i) larger dimension of frame member (650mm)

ii) 1/6th of clear span (575mm)

iii) 450mm

So $l_o$= 650mm

As per cluase 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 longitudinal rebar (120mm)

iii) 100mm

So maximum shear link spacing maintained = 100mm

 

Minimum special confining reinforcement should be maximum of (a) and (b)

(a) $A_{sh}$= 0.18 $s_{v}h\left(\frac{f_{ck}}{f_y}\right)(\left(\frac{A_g}{A_k}\right)-1)$

(b) $A_{sh}$= 0.05 $s_{v}h\frac{f_{ck}}{f_y}$

 

(a) $A_{sh}$= 631 sq.mm/m

(b) $A_{sh}$= 337 sq.mm/m

 

Required minimum special confining reinforcement at joint $A_{sh}$= 631 sq.mm

Provided shear reinforcement at joint = $\left(\frac{1000}{100}\right)$x 4 legs x area of 8mm dia rebar (50.3 sq.mm) = 2010 sq.mm

Hence OK.

 

 

Result: detailing of given column RC member is done with check on special confining reinforcemnt is done for shear reinforcement,

             

      Detailing of grid A3 column                                                                                                                                             

                                                                                  

 

 

 

 

Detailing of grid B3 column