Reinforcement detailing of Columns from ETABS output

Reinforcement Detailing of Columns from ETABS output.

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 Providing details of longitudinal reinforcement for the two columns from foundation to Terrace level.

Introduction:

Column reinforcement according to IS: 13920 code book clause 7

Longitudinal Reinforcement:

• Minimum dimension of a column shall not be less than 20db largest diameter of longitudinal reinforcement bar in the beam which is passing through column and 300mm.
• Aspect ratio i.e., B / D should not be less than 0.45
• In lap splices

1. Spacing of link shall not exceed 100mm.
2. Lap splices should not be less than development length of largest reinforcement bar.

• Lap splices shall be provided at center of column height, not within joint or not within a distance of 2d from joint.

1. Not more than 50% of area of steel bars shall be spliced at any one section.
2. Lap splices shall not be used for bars of diameter more than 32mm.

Procedure:

Step: -1

• Open a G+4 Etabs file.
• Click the concrete frame design tool.
• Select the display design info option.
• Choose design output as longitudinal reinforcement.

Step: -2

• After, selecting the longitudinal reinforcement click elevation view.
• To avoid the confusions, click tick mark on ribbon and uncheck. Beam.

Step: -3

• Now need to calculate the reinforcement details of 3A & 3B.

Step: -4

• For shear reinforcement, click the concrete frame design tool.
• Choose shear reinforcing.
• Click apply & OK.

Step: -5

After selecting the shear reinforcement option, the shear reinforcement values are obtained at each column.

Longitudinal Reinforcement & Shear Reinforcement of Column at Grid-3A from Etabs (450x650):

Storey Assignment tab to refer elevation of column.

Step: -6

Note:

1. Minimum Longitudinal Reinforcement as per IS-456-2000 clause 26.5.3.1 As = 2340 mm2.
2. Minimum Shear Reinforcement as per IS-13920-2016 clause 7.4.2- 8mm dia @ 300mm c/c

GRID A:

Calculation for Longitudinal Reinforcement:

• From base to first floor the maximum Ast is = 6926 mm²

= 6926 / 10 = 692 mm²

= Considering 32 mm dia = Ast = 804 mm²

• So, we can provide 10# of 32 mm dia Longitudinal bar= 10 x 804 = 8040 mm²

Calculation for Shear Reinforcement:

• From base to first floor the maximum shear value is = 720 mm²

=(1000/Sv) X L x Ast

= 1000/200 x 2 x 78.55

=785.5 mm²

• So, we can provide 10mm dia @200 mm spacing shear.

GRID B:

Calculation for Longitudinal Reinforcement:

• From base to first floor the maximum Ast is = 5046 mm²

  = 5046 / 8 = 630.75 mm²

  = Considering 32 mm dia = Ast = 804 mm²

• So, we can provide 8#32 mm dia Longitudinal bar = 8 x 804 =6432 mm²

Calculation for Shear Reinforcement:

• From base to first floor the maximum shear value is = 720 mm²

=(1000/Sv) X L x Ast

= 1000/200 x 2 x 78.55

=785.5 mm²

• So, we can provide 10mm dia @200 mm spacing shear.

Therefore, it can be satisfied the entire span.

Step: -7

Elevation & Cross sectional details of Column using AutoCAD:

Beam Elevation @ Grid-3A Beam Elevation @ Grid-3B

Beam cross section @ Grid-3A Beam cross section @ Grid-3B

RESULT.

• The Columns are designed successfully in detail from the ETABS software.
• Provided the details of longitudinal reinforcement for the two columns (3A & 3B) successfully.
• And calculated the value of Maximum Ast in columns using the ETABS.
• And also provided the column cross sectional & Elevation details using the AutoCAD software.