Steel Beam Web Stiffener Analysis Calculator

Web Yielding, Crippling, Buckling, and Stiffener Criteria for Concentrated Load or Reaction
Per AISC 9th Edition Manual (ASD)

Input Data

Beam Size:
Select:
P or R = kips
Design Parameters:
Beam Yield, Fyb = kips
Bearing Length, N = in.
Unbraced Length, Lb = ft.
Distance to P or R, x = ft.
Stiffener Thickness, ts = kips
Stiffener Yield, Fys = kips
Number of Stiff. Pairs =
Beam Properties:
d = in.
tw = in.
bf = in.
tf = in.
k = in.

Results

Gross Shear Capacity of Beam Web:
Rv = kips Rv = 0.40*Fyb*d*tw
Local Web Yielding:
Rwy = kips
Web Crippling:
Rwc = kips

Sidesway Web Buckling:
h = in. h = d-2*tf
dc = in. dc = d-2*k
(dc/tw)/(Lb/bf) =
Rwb = kips

Beam Web Stiffener Design:
(Note: stiffeners are assumed to be full depth, from flange to flange.)
Stiffener Width:
bs(min) = in. bs(min) = 2/3*bf/2-tw/2
bs = in. bs = bf/2-tw/2 (rounded down to nearest 1/2 inch)
Stiffener Thickness:
ts(min) = in. ts(min) = larger of: tf/2 or bs*SQRT(Fys)/95
Check Stiffener Slenderness and Compressive Stress:
b/t =   b/t = bs/ts
b/t(max) =   b/t(max) = 95/SQRT(Fys)
K =   (assumed effective length factor per AISC Code, page 5-82)
L = in. L = h = d-2*tf
I = in.^4
A = in.^2
r = in. r = SQRT(I/A)
fa = ksi
KL/r =   (effective slenderness ratio for compression)
Cc =   Cc = SQRT(2*p^2*29000/Fys)
Fa = ksi If KL/r <= Cc:
Fa=(1-(K*L/r)^2/(2*Cc^2))*Fys/(5/3+3*(K*L/r)/(8*Cc)-(K*L/r)^3/(8*Cc^3))
If KL/r > Cc: Fa = 12*p^2*29000/(23*(K*L/r)^2)

Stiffener Welding to Beam Flange:
Ps = kips
Lw = in.
fw = kips/in. fw = Ps/Lw
w(req'd) = in. (size) w(req'd) = fw/((SQRT(2)/2)*(0.30*70))
w(min) = in. w(min) = Min. fillet weld size from AISC Table J2.4, page 5-67
w(max) = in.

Stiffener Welding to Beam Web:
Ps = kips
Lw = in.
fw = kips/in. fw = Ps/Lw
w(req'd) = in. (size) w(req'd) = fw/((SQRT(2)/2)*(0.30*70))
w(min) =   in. w(min) = Min. fillet weld size from AISC Table J2.4, page 5-67
w(max) = in.

SUMMARY OF CHECKS:
Row No.: Results: Stress Ratio:
Gross Shear Capacity of Beam Web:
35
Local Web Yielding:
38
Web Crippling:
42
Sidesway Web Buckling:
49
Beam Web Stiffner Design:
60
76
84

92

Max. Allowable P without Stiffeners:
R(max) = kips
TABLE J2.4
Minimum Size of Fillet Welds
 Material Thickness of Thicker Part Joined (in.) Minimum Size of Fillet Weld (in.) To 1/4 inclusive 1/8 Over 1/4 to 1/2 3/16 Over 1/2 to 3/4 1/4 Over 3/4 5/16
For 1-pair of stiffeners, assumed effective width of beam
web to be included in composite section is as follows:
For 2-pairs of stiffeners, assumed effective width of beam web
to be included in composite section is as follows:
For end load/reaction (R):       12*tw+3" For 3-pairs of stiffeners, assumed effective width of beam web
to be included in composite section is as follows:
For 1-pair of stiffeners, assumed effective width of beam
web to be included in composite section is as follows:
For 2-pairs of stiffeners, assumed effective width of beam
web to be included in composite section is as follows:
For 3-pairs of stiffeners, assumed effective width of beam
web to be included in composite section is as follows:
Note on Fillet Weld Size vs. Connected Material Thickness:

The minimum connected material (base metal) thickness to
develop a given fillet weld size is
determined by equating the base metal shear strength
to the fillet weld shear strength as follows:

t(min) = (w *(SQRT(2)/2)*0.30*70*(N))/(0.40*Fy)
where: t(min) = minimum thickness of connected material (in.)
w = fillet weld leg size (in.)
N = 1 for weld on only one side of material thickness
N = 2 for weld on both sides of material thickness
Fy = yield strength of base metal (ksi)
E70XX weld electrode is assumed above (70 ksi yield)
Case 1 - For fillet weld on one side of material thickness:
t(min) = 1.031*w   (for Fy = 36 ksi material)
t(min) = 0.742*w   (for Fy = 50 ksi material)
Case 2 - For fillet weld on both sides of material thickness:
t(min) = 2.062*w   (for Fy = 36 ksi material)
t(min) = 1.485*w   (for Fy = 50 ksi material)
Note on Fillet Weld Size vs. Connected Material Thickness:

The minimum connected material (base metal) thickness to
develop a given fillet weld size is
determined by equating the base metal shear strength
to the fillet weld shear strength as follows:

t(min) = (w *(SQRT(2)/2)*0.30*70*(N))/(0.40*Fy)
where: t(min) = minimum thickness of connected material (in.)
w = fillet weld leg size (in.)
N = 1 for weld on only one side of material thickness
N = 2 for weld on both sides of material thickness
Fy = yield strength of base metal (ksi)
E70XX weld electrode is assumed above (70 ksi yield)
Case 1 - For fillet weld on one side of material thickness:
t(min) = 1.031*w   (for Fy = 36 ksi material)
t(min) = 0.742*w   (for Fy = 50 ksi material)
Case 2 - For fillet weld on both sides of material thickness:
t(min) = 2.062*w   (for Fy = 36 ksi material)
t(min) = 1.485*w   (for Fy = 50 ksi material)
If Rv < R, then increase beam size,
namely depth (d) and/or web thickness (tw).
If Rwy < P or R, then bearing
stiffeners are required for the web.
If Rwc < P or R, then bearing
stiffeners are required for the web.
If Rwb < P or R, then bearing
stiffeners are required for the web.
If ts < ts(min), then increase
stiffener plate thickness (ts).
If Fa < fa, then increase
stiffener plate thickness (ts).
If weld size > max. weld,
then increase stiffener plate thickness (ts).
If weld size > max. weld, then
increase stiffener plate thickness (ts).
If Rv < R, then increase beam size,
namely depth (d) and/or web thickness (tw).
If Rwy < P or R, then bearing
stiffeners are required for the web.
If Rwc < P or R, then bearing
stiffeners are required for the web.
If Rwb < P or R, then bearing
stiffeners are required for the web.
If ts < ts(min), then increase
stiffener plate thickness (ts).
If Fa < fa, then increase
stiffener plate thickness (ts).
If weld size > max. weld,
then increase stiffener plate thickness (ts).
If weld size > max. weld, then
increase stiffener plate thickness (ts).

Disclaimer: This calculator is not intended to be used for the design of actual structures, but only for schematic (preliminary) understanding of structural design principals. For the design of an actual structure, a competent professional should be consulted.

‘Calculations courtesy of Alex Tomanovich, PE ’