HOW TO CALCULATE CUTTING LENGTH OF BENT UP BAR ?
TO CALCULATE CUTTING LENGTH OF BENT UP BAR THE FIRST THING YOU SHOULD KEEP IN YOUR MIND, IS CAREFULLY OBSERVE THE DRAWING AND AVAILABLE DATA.
KNOWN DATA,
Dia of bar = 12mm
Clear span= 6000mm
Clear cover = 25mm
Ld = development length=40d =
40X12=480mm
Slab thickness = 200 mm
(FORMULA:- Cutting length of bent up
bar= clear span +inclined length-bends )
NOW,
CLEAR SPAN IS 6000 mm (GIVEN)
INCLINED LENGTH =?
NOTE:-If the bar is cranked at 45˚ then its
inclined length is 0.42H
& if the bar
is cranked at 30˚ then its inclined length is 0.27H
HERE, the angle formed is 45˚
THEREFORE,
INCLINED LENGTH =0.42H
WHERE, H=slab thickness -2(clear cover)-dia
of bar
=200-2(25)-12 =138mm
IN THIS FIGURE, WE CAN SEE THAT THERE ARE 4, 45˚ AND 2, 90˚ BENDS
AND AS WE KNOW FOR 1 FORTY FIVE DEGREE WE DEDUCT 1d, AND FOR 1 NINTY DEGREE WE DEDUCT 2d.
NOW LETS PUT ALL THE VALUES IN THE MAIN FORMULA
Cutting length of bent up bar= clear span +inclined length-bends
clear span +Ld +0.42H-bends
=clear
span + 2(Ld)
+2(0.42H) -4(1d)-2(2d)
=6000+2(480)+2(0.42X138)-4(1X12)-2(2X12)
=6979.9 mm
=6.977 m
=7m
THEREFORE CUTTING LENGTH OF BENTUP BAR IS 7M.