EXAMPLE 7.8.1. ESTIMATING COLUMN REINFORCEMENT (LOW-RISE)

Estimate the reinforcement and tie wire needed for the 8 columns of a two storey residential building. Depth of column into the footing is 1.0 meters and the height of each floor from ground to second and from second floor to roof is 3.00m. Column dimensions are 0.30m x 0.30m. Use 8pcs D16mm vertical reinforcement and D12mm ties are spaced at 3 @ 0.05m; 4 @ 0.075m; 4@0.10m; and rest @ 0.15m to center line.

MAIN REINFORCEMENT:

As the number of bars in a column is already given, determine the length of each bar.

So:

 


LATERAL TIES:


     

     

To easily visualize the number of ties, draw a line representing the height of the column. Place the lateral ties from the spacing given in the plans.

The center line is located at the midlength of the column and the lateral ties will be mirrored at the other side from this line.

For the column length: Footing to Ground floor, there are 7 ties needed until center line. If these ties are mirrored to the upper half, there will be a middle (remaining) space of 0.10m. Note that 0.10m is still within the range of the next lateral tie spacing.

Thus for footing to Ground flr:

     

For Ground floor to Second flr:

   

There are 240 ties from Second flr to Roof beam.

Finally, 





#16 GI TIE WIRE

The required tie wire depends on the number of intersections between the main reinforcement and the lateral ties.

For every column, there are 8 main bars and 74 lateral ties (14+30+30).


      


     


With the combination of D16mm and D12mm to be tied, it is safer to take a longer tie wire, use 30cm.



In summary:

Materials required:

      64    pcs       D16mm by 7.50m
      592 pcs        D12mm x 1.10m
      27   kg         #16 GI Tie Wire




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