BAR BENDING SCHEDULE FOR COLUMN DETAILED PRACTICAL GUIDE

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In this post, we are going to explain “How to make bar bending schedule for Column?”

This article will be quite long. Brace Yourself.

First of all, there are some criteria & assumptions that need to be met while making bar bending schedule for a column. Let’s get started.

Loads Acting on Column

We hope that you know the typical load action on a column.

Just take a look at the below diagram.

If you see the internal forces and moment diagram, the column has maximum moments at top and bottom and less at centre.

Never tie a column at top & bottom where the critical moment is high. Always tie the column at centre.

For practical always tie the bars at 5 feet height. Since every roof should not be more than 10 feet.

·         Minimise the cutting of bar and lapping as often as possible.

·         Always lap alternate bars at a time.

·         Always overlap top bars with bottom bars.

·         Maintain sufficient end to end spacing between the laps.

Bar Bending Schedule for Column

From the diagram,

·         Slab Thickness – 125 mm & 100 mm

·         Floor height – 3000 mm or 3 m

·         Ground Floor Level – 3300 mm

·         Footing Height – 300 mm

·         Development Length – 50d

·         Column has 6 numbers of 20 mm dia bars

·         8mm stirrups @ 150 mm C/C

·         Footing Clear Cover – 40 mm

·         Slab Clear Cover – 25 mm

Step 1 – Find the length of Vertical Bar

Length of Vertical bar = Development length (Ld) + Height of Ground Level + Floor Heights (1,2,3)+ Slab Thicknesses + Overlap Length (Det.B)

= (50×20)+3300+ (3×3000)+(3×125)+100 +(50×20)

= 14775 mm or 14.78 m

Now we know the length of one vertical bar. Normally column reinforcement drawings won’t come with lapping details.

Step 2 – Find out lapping

As we know that lapping length required is 50d = 50 * Diameter of the bar = 50×20 = 1000 mm.

We know that each bar is 12.25 m or 40 feet length (approx).

Total Length of Vertical Bar = 14.2 m which is more than 12.25 m so each rod will be lapped at least once to attain the required length.

So we have added the lapping length with the total length = 14775+1000 = 15775 mm or 15.78 m

As we mentioned earlier in this post, consider the points while lapping the bar. There is no one correct method we can use. Just remember the lines.

·         Never tie a column at top & bottom

·         Always lap at alternate bars

·         Always overlap top bars with bottom bars

Step 3 – Cutting Length of Stirrups

Length of One Hook = 9d (As per Estimating and Costing in Civil Engineering P.No.214)

Cutting length of Stirrup = Perimeter of stirrup + Number of Bends + Number of Hooks

= 2(a+b) + 3 numbers of 90 degree bends + 2 numbers of hooks

= 2(500+200)+(3 x2d)+(2x9d)= 2×700+3x2x20+2x9x20

Cutting length of Stirrup = 1880 mm

Step 4 – Number of Stirrups

Number of stirrups required = (Total length of Column/spacing of stirrups)+1

      = (3300+125+3000+125+3000+125+3000+100)/150 + 1

Number of stirrups                = 85 no.s

Step 5 – Bar Bending Schedule

	Diameter of Bar	Numbers	Cutting Length	Total Length
Vertical bar	20 mm	6	14.2 m	85.2 m
Stirrups Bar	8 mm	85	1.88 m	159.8 m

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