www.sefindia.org

[sspawar]

Dear Sefians,
At many places in You Tubes and web sites, and forums, stirrups cutting length, bend and hooks  are explained in many ways following the thumb rules (of no basis) and many times with misconceptions which lead the questioners and seekers at no point and confused.
Some say for each 45 degree bend one D is deducted from overall length, some say it should be added, some say hook length will be 9d or 10d or 6d or anything.
Some say IS code gives insufficient information hence can’t be followed exclusively.
I tried to explain on basis of IS code 2502 through a illustration which gives a complete picture how each and every length can be defined and calculated.
Regards

[vikram.jeet]

I think , we must differentiate between ANCHORAGE VALUE OF BEND /HOOK and LENGTH OF BAR consumed in bend (bend allowance / hook (hook allowance).

ANCHORAGE value of  bend is 8*bar dia for each 90 degree bend and for hook it is 16*bar dia. ( I.e. 4 *dia for every 45 deg bend)

Bend / Hook Allowance

Keeping in view the radius of bar ( cold twisted) being 4D and extra straight portion beyond bend / hook as also 4D

additional length consumed in 90 degree bend is around                    = 2π * (4D)/4 + 4D ~ 10D
Net bend allowance (since radius 4D is already taken in Bar straight Length ) = 6D

Similarly for hook  it works to around = 2π* (4D)/ 2 + 4D ~ 16 D
Net hook allowance = 12D
Above is based on inner radius of bend / hook  and π value taken approx as 3.0 . But it may be slightly higher taking centerline radius of bar and value of π as 3.142.

[sspawar]

Dear Sefians and Vikram Jeet Sir,
In the above topic I was only concerned of BBS preparation in light of IS 2502 for bend and hook of mainly of stirrups.
Whereas Design requirement  of reinforcement detailing regarding anchorage etc should be followed as per  IS 456 Clause 26.  

I further elaborated by sketch the stirrups of 135 degree hook detailing and last para of earlier pdf attachment is edited. Who have downloaded earlier PDF may go through the edited /updated PDF attachment in respect of 135 degree bend.

Regards

[vikram.jeet]

Dear Pawar saheb,

I appreciate you for bringing this delicate aspect into limelight as there always exist confusion and definitely your attachment is useful to all of us on sefi .

For BBS purpose / reinf quatty calculations   , the enlightenment of additional allowance  for  bars will end up in correct cutting of bars as also actual quatty consumption.

Please keep it up and best regards

[sspawar]

Dear Sefians,

I added a explanatory note here in continuation for stirrups having 90 degree bends at the end instead of 135 degree hooks.
Also has been given references of IS 456 and IS 13290.

Regards

[sspawar]