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 of 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 the special confining reinforcement provision of clause 8.1 of IS 13920 - 2016.

AIM

To analyse and design the RCC moment-resisting frame of the given ETABS file and provide details of longitudinal reinforcement for the two columns (3A and 3B) from foundation level to terrace level.

To sketch the column cross-sectional & elevation details or draft it using AutoCAD software.

To show shear reinforcement & lapping details as per the special confining reinforcement provision of clause 8.1 of IS 13920-2016.

PROCEDURE

Open the given ETABS file.

Then check the model for errors and carry out the analysis.

Once the analysis is complete, carry out the design procedure.

Go to Concrete frame design, then Design preferences.

Go to Concrete frame design, then Design combinations.

Go to Concrete frame design, then Start design check

Go to Concrete Frame Design> Display Design Info> Longitudinal Reinforcing

Go to Concrete Frame Design> Display Design Info> Shear Reinforcing

Now, we need to draft the column reinforcement details on AutoCAD.

COLUMN 3A

Longitudinal Reinforcement

The maximum A_st required in the column is 7027 mm².

Hence providing 12 bars of 28 mm diameter

= 615.44*12 =7385mm² >7027mm²

Shear Reinforcement

Provide 8mm diameter lateral ties @150mm c/c

Confinement Arrangement

The length of the confinement region (L₀) is the maximum of the following

1. Larger lateral dimensions of the member where yielding occurs
2. 1/6th of the clear column span
3. 450 mm

Therefore, we shall consider the confinement region up to 600 mm from the beam bottom towards the mid-span on either side of the column.

Shear Spacing within the confinement region is the least of the following

1. 1/4th of the smaller lateral dimension of column
2. 6 x diameter of smallest longitudinal bar
3. 100mm

Therefore, provide 100mm c/c spacing within the confinement zone and go with 150mm c/c for the mid-zone of the column.

COLUMN 3B

Longitudinal Reinforcement

The maximum A_st required in the column is 5046 mm².

Hence providing 8 bars of 25 mm diameter = 490.625*8 = 3925mm²

And 4 bars of 20 mm diameter = 314*4 = 1256mm²

Total = 3925 + 1256 =5181 mm² > 5046 mm²

Shear Reinforcement

Provide 8mm diameter Lateral Ties @150mm c/c

Confinement Arrangement

The length of the confinement region (L₀) is not less than

1. Larger lateral dimensions of the member where yielding occurs
2. 1/6th of the clear column span
3. 450 mm

Therefore, we shall consider the confinement region up to 600 mm from the beam bottom towards the mid-span on either side of the column.

Shear Spacing within the confinement region is not more than

1. 1/4th of the smaller lateral dimension of the column
2. 6 x diameter of smallest longitudinal bar
3. 100mm

Therefore, provide 100mm c/c spacing within the confinement zone and go with 150mm c/c for the mid-zone of the column.