V. AISC ASD - Design of Steel Beam with Web Opening
Design the web reinforcement for a web opening in a steel beam.
Details
Design Method : ASD
Beam No : 5
Beam Section : W21X50
- d = 20.83 in
- tw = 0.38 in
- bf = 6.53 in
- tf = 0.535 in
- Z = 110 in3
- L = 10 ft
Weld Properties : E90XX
Fy,weld = 90 ksi
Weld Stress = 54 ksi
Opening Type: Rectangular
Number of openings : 1
- Section location of Opening : 0.6
- a0 = 20 in
- h0 = 10 in
- e = 0 in ( concentric opening )
- Fy = 36 ksi
Capacity check at web hole assuming an unreinforced opening:
Loading :
- Vu = 34.46 kip
- Mu = 2,510.7 kip-inch
Tee Properties :
- st = 5.415 in
- sb = 5.415 in
Calculations
Validation
Check for local buckling of compression flange :
width to thickness ratio
limiting ratio Hence O.K
Check for web buckling :
width to thickness ratio of web
limiting ratio Hence O.K
Check for opening dimensions to prevent web buckling :
Since , a0 / h0 = 2 < 3.0
h0 / d = 0.4801 < 0.7
Opening parameter Hence OK
Check for Tee dimension :
Aspect Ratio:
,
Hence OK
Calculation of Maximum Moment Capacity :
For unperforated section Mp = FyZ = 3,960 kip-inch
Hence OK
Calculation of Maximum Shear Capacity
For unreinforced opening :
Ratio of nominal shear capacity of tees :
Hence OK
Vm = Vmb+Vmb = 38.618 kips Hence OK
Check against Maximum Shear capacity :
Since , Hence OK
Check against Moment Shear Interaction:
Not OK… Try with a Reinforced web opening .
Capacity check at web hole assuming a reinforced opening:
Reinforcement should be selected to reduce R to 1.0
Let us assume,
- Thickness of Reinforcement tr = 0.1875 in
- Width of Reinforcement br = 0.25 in
Check for local buckling of compression flange :
width to thickness ratio of web reinforcement
limiting ratio Hence O.K
Area of Reinforcement Ar = trbr = 0.0469 in2
Calculation of Maximum Moment Capacity :
For unperforated section Mp = FyZ = 3,960 kip-inch
Since twe = 0 < Ar
Hence OK
Calculation of Maximum Shear Capacity :
Hence Ok
,
,
Hence OK
Check against Maximum Shear capacity :
Since , kips Hence OK
Check against Moment Shear Interaction :
Hence OK
Calculation of length of Fillet Weld :
For reinforcing bars on one side of the web :
Hence OK
a0 / h0 = 2 ≤ 2.5 Hence OK
,
Hence OK
Hence OK
(strength of weld within the length of the opening)
(length extended on each side of the opening)
Thus, Length of bar = a0 + 2L1 = 30 in
(strength of weld for extension on each side of opening)
Strength of Weld Rwr = max(Rwr1, Rwr2) = 3.375 kips
Fillet Weld Size = 0.0044 in (rounded to nearest weld size of 0.0625 in = 1/16 in)
Corner Radii :
Minimum Radii
Results
| Result Type | Reference | STAAD.Pro | Difference | Comments | |
|---|---|---|---|---|---|
| Interaction Ratio, R | 0.99 | 1.00 | negligible | ||
| Reinforcement bar (required at web opening) | Length, in | 30 | 30 | none | |
| Width, in | 0.25 | 0.25 | none | ||
| Thickness, in | 0.1875 | 0.1875 | none | ||
| Fillet Weld Size, in | 1/16 | 0.0625 (1/16") | none | ||
Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2026\Samples \Verification Models\09 Steel Design\US\AISC\AISC ASD - Design of Steel Beam with Web Opening.std is typically installed with the program.
STAAD
STAAD PLANE Design of Steel Beam with Web Opening
START JOB INFORMATION
ENGINEER DATE 18-May-05
END JOB INFORMATION
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 30 0 0; 3 0 20 0; 4 10 20 0; 5 20 20 0; 6 30 20 0; 7 0 35 0;
8 30 35 0; 9 7.5 35 0; 10 22.5 35 0; 11 15 35 0; 12 5 38 0; 13 25 38 0;
14 10 41 0; 15 20 41 0; 16 15 44 0;
MEMBER INCIDENCES
1 1 3; 2 3 7; 3 2 6; 4 6 8; 5 3 4; 6 4 5; 7 5 6; 8 7 12; 9 12 14;
10 14 16; 11 15 16; 12 13 15; 13 8 13; 14 9 12; 15 9 14; 16 11 14;
17 11 15; 18 10 15; 19 10 13; 20 7 9; 21 9 11; 22 10 11; 23 8 10;
MEMBER PROPERTY AMERICAN
1 3 4 TABLE ST W14X90
2 TABLE ST W10X49
5 6 7 TABLE ST W21X50
8 TO 13 TABLE ST W18X35
14 TO 23 TABLE ST L40404
MEMBER TRUSS
14 TO 23
MEMBER RELEASE
5 START MZ
UNIT INCHES KIP
DEFINE MATERIAL START
ISOTROPIC MATERIAL1
E 29000
POISSON 0.3
DENSITY 0.000283
ISOTROPIC STEEL
E 29732.7
POISSON 0.3
DENSITY 0.000283
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
CONSTANTS
BETA 90 MEMB 3 4
MATERIAL MATERIAL1 MEMB 1 TO 4 6 TO 23
MATERIAL STEEL MEMB 5
UNIT FEET KIP
SUPPORTS
1 FIXED
2 PINNED
PRINT MEMBER INFORMATION LIST 1 5 14
PRINT MEMBER PROPERTIES LIST 1 2 5 8 14
LOAD 1 DEAD AND LIVE LOAD
SELFWEIGHT X 1
SELFWEIGHT Y -1
JOINT LOAD
4 5 FY -15
11 FY -35
MEMBER LOAD
8 TO 13 UNI Y -0.9
6 UNI GY -1.2
CALCULATE RAYLEIGH FREQUENCY
LOAD 2 WIND FROM LEFT
MEMBER LOAD
1 2 UNI GX 0.6
8 TO 10 UNI Y -1
* 1/3 RD INCREASE IS ACCOMPLISHED BY 75% LOAD
LOAD COMB 3 75 PERCENT DL LL WL
1 0.75 2 0.75
LOAD COMB 4 75 PERCENT DL LL WL
1 2.75 2 2.75
PERFORM ANALYSIS
LOAD LIST 4
UNIT INCHES KIP
PARAMETER
CODE AISC
*WEB OPENINGS
*********************
RHOLE 0.6 MEMB 5
RDIM 20.0 10.0 MRMB 5
electrode 3
*********************
CHECK CODE MEMB 5
FINISHOutput
STAAD.Pro CODE CHECKING - (AISC 9TH EDITION) v1.0
***********************
ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE Noted)
MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/
FX MY MZ LOCATION
=======================================================================
* 5 ST W21X50 (AISC SECTIONS)
FAIL AISC- H2-1 2.268 4
50.64 T 0.00 -4151.62 120.00
OUTPUT FOR WEB OPENING
----------------------
SECTION LOAD MZ/ FY/ IR
MOM. CAP. (Mm) SHR. CAP. (Vm) ((MZ/Mm)^3+(FY/Vm)^3)^0.33
=======================================================================
0.600 4 2510.65 34.46
3634.88 39.64 1.00
REINFORCING BARS : TO BE PLACED ON ONE SIDE OF WEB
BAR DIMENSION : LENGTH = 30.00 WIDTH = 0.25 THICKNESS = .1875
FILLET WELD : SIZE REQD = 0.0625 inch LENGTH REQD = 30.00
======================= END WEB OPENING OUTPUT ========================