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# Couldn't find the equations in LRFD

## Couldn't find the equations in LRFD

(OP)
hi all,
I'm studying the Akbar R. Tamboli's LRFD book to better grasp concept of LRFD approach, downloaded the latest version of AISC LRFD specification from AISC site(Specification for Structural Steel Buildings). In the book there is the example of "Three Way Moment Connection" many checks has been performed and had posed many equations to verify that beam to column connection requires the stiffeners, doubler plates etc in order to keep limit states(bearing, BSR, flexure etc..) at required limits. But I can't locate these equations in the downloaded LRFD specification file ?
Couple of them are listed below :

min. column sitiffener width
ws = Bfb/2-Twc/2

column web yielding formula
Pwy = Pwo + tƒ Pwi

column minimum stiffener length
Dc/2-Tc

stiffener plate buckling check
Ts>=Ws*squareroot(Fy)/95

and many other limit considerations for doubler plates
For example : the books says that panel zone strength could be increased if deflections is acceptable and if considered in analysis and refers to formula "AISC LRFD Specification Eq. K1-11 or Eq. K1-12" ( 3*Bfc*Tfc^2/(Db*Dc*Twc) ) which will act as multiplier for basic strangth fi*Vv. But when I'm trying to find that formula I come across completely with different under the K section.

Probably the book is old or I'm refering to completely wrong specification.

Regards,

### RE: Couldn't find the equations in LRFD

What steel specification are you using?  The following references are for the 2005 ASD/LRFD specification, found in the 13th edition manual.

min. column sitiffener width
ws = Bfb/2-Twc/2

Section J10.8, on page 16.1-121.

column web yielding formula
Pwy = Pwo + tƒ Pwi

This is in the manual portion, not the specification.  Pwo and Pwi are allegedly helpful values corresponding to parts of the web local yielding equation.  Pwo and Pwi are the old 9th edition ASD variable names.  They are called R1 and R2 in the 13th edition, on page 9-18 and Table 9-4, starting on page 9-38.

column minimum stiffener length
Dc/2-Tc

Section J10.8, on page 16.1-121.

stiffener plate buckling check
Ts>=Ws*squareroot(Fy)/95

Limiting b/t ratio, Table B4.1, case 3, on page 16.1-16.  0.56(E/Fy)^0.5 = 95/Fy^0.5

### RE: Couldn't find the equations in LRFD

(OP)

>What steel specification are you using?  The following references are for the 2005 ASD/LRFD specification, found in the 13th edition manual

I'm using "Specification for Structural Steel Buildings, March 9, 2005" downloaded from aisc.org page don't know whih edition it's but I presume that it should be the latest version.

>min. column sitiffener width ws = Bfb/3-Twc/2 Section >J10.8, on page 16.1-121
.....
.....

My bad, I was looking for something like equation but it's been written there.

>and many other limit considerations for doubler plates For example : the books says that panel zone strength could be increased if deflections is acceptable and if considered in >analysis and refers to formula "AISC LRFD Specification >Eq. K1-11 or Eq. K1-12" ( 3*Bfc*Tfc^2/(Db*Dc*Twc) ) which >will act as multiplier for basic strangth fi*Vv. But when I'm >trying to find that formula I come across completely with different under the K section.

How about that formula K1-11 or K1-12 in specification  Section K1.6 on page 16.1-126.

Regards,

### RE: Couldn't find the equations in LRFD

K1-11 and K1-12 are references to the old 3rd edition LRFD specification.  For the 2005 specification, these are equations J10-11 and J10-12.

### RE: Couldn't find the equations in LRFD

(OP)
thanks,

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