V. AISI 2016 Cylindrical Tubular Section
Determine the flexural strength of a closed cylindrical tubular member subjected to axial compression and bending moment according to AISI S100 2016 specification.
Reference
Cold-Formed Steel Design: AISI Manual. 2013 ed. Washington, D.C.: American Iron and Steel Institute, 2014. Example II-8.
Details
The member is a 10' simply-supported span. The section is a 8" diameter closed cylindrical tube with a wall thickness of 0.1".
Axial loads:
- Dead load: PDL = 7.5 kips
- Roof live load: PLR = 20 kips
Transverse loads:
- Wind load: PW = 50 kips (concentrated load at mid-span)
Section properties:
- Area: A = 2.482 in2
- Moment of inertia: I = 19.37 in4
- Section modulus: Sf = 4.841 in3
- Radius of gyration:
Material properties:
- E = 29,500 ksi
- G = 11,300 ksi
- Fy = 42 ksi
- Fu = 58 ksi
Validation
Design forces:
Governing load combination is DL + RLL + WL
Mu = 1.0 (5 kips) (120 in)/4 = 150 in·kips
Section Dimension Checks
Check the outside diameter to wall thickness ratio:
D / t = 8.0 / 0.1 = 80
Hence, OK.
Determine Axial Capacity
Determine the governing equation for Fn :
Since:
Determine Flexural Capacity
Nominal flexural strength (resistance) for yielding and global buckling:
Allowable flexural strength (ASD):
Design flexural strength (LRFD):
Results
| Result Type | Reference | STAAD.Pro | Difference | Comments |
|---|---|---|---|---|
| Flexural strength, ASD (in·kips) | 140 | 139.481 | negligible | |
| Flexural strength, LRFD (in·kips) | 221 | 221.286 | negligible |
STAAD.Pro Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2024\Samples \Verification Models\09 Steel Design\US\AISI\AISI 2016 Cylindrical Tubular Section.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 06-Apr-20
END JOB INFORMATION
INPUT WIDTH 79
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 0 10 0;
MEMBER INCIDENCES
1 1 2;
UNIT INCHES KIP
DEFINE MATERIAL START
ISOTROPIC STEEL
E 29500
POISSON 0.3
DENSITY 0.000283
ALPHA 6.5e-06
DAMP 0.03
TYPE STEEL
STRENGTH RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY COLDFORMED AMERICAN
1 TABLE ST PIPE OD 8 ID 7.8
CONSTANTS
MATERIAL STEEL ALL
UNIT FEET KIP
SUPPORTS
2 FIXED BUT FY MX MZ
1 FIXED BUT MX MZ
UNIT INCHES KIP
LOAD 1 LOADTYPE Dead TITLE LOAD CASE 1
MEMBER LOAD
1 CON GY 7.5 0
1 CON GY -7.5 120
LOAD 2 LOADTYPE Roof Live TITLE LOAD CASE 2
MEMBER LOAD
1 CON GY 20 0
1 CON GY -20 120
LOAD 3 LOADTYPE Wind TITLE LOAD CASE 3
MEMBER LOAD
1 CON GX 5
LOAD COMB 4 ULC D+0.45W+0.75L
1 1.0 3 0.45 2 0.75
LOAD COMB 7 ULC, 1 DEAD + 1 ROOF LIVE
1 1.0 2 1.0
LOAD COMB 8 ULC, DEAD + 0.6 WIND
1 1.0 3 0.6
PERFORM ANALYSIS
LOAD LIST 4 7 8
PARAMETER 1
CODE AISI 2016
METHOD LRFD
FYLD 42 ALL
TRACK 2 ALL
CHECK CODE ALL
PARAMETER 2
CODE AISI 2016
METHOD ASD
FYLD 42 ALL
TRACK 2 ALL
CHECK CODE ALL
FINISH
STAAD.Pro Output
STAAD.Pro CODE CHECKING - (AISI S100-16) [LRFD] (v1.0)
********************************************************
ALL UNITS ARE IN "INCH" AND "KIP " (U.N.O.)
|-----------------------------------------------------------------------------|
| MEMBER: 1 SECTION:ST PIP E LEN: 120.000 LOC: 60.000 |
| STATUS: PASS RATIO: 0.657 REF: Eq. H1.2-1 LC: 4 |
|-----------------------------------------------------------------------------|
| DESIGN FORCES: |
| Location: 60.000 Criteria: Eq. H1.2-1 LC: 4 |
| Fx:(C) 22.500 Fy: 1.125 Fz: -0.000 |
| Mx: 0.000 My: -0.000 Mz: -67.500 |
|-----------------------------------------------------------------------------|
| SECTION PROPERTIES: |
| Ag: 2.48186 Az: 1.24093 Ay: 1.24093 |
| Cz: 0.00000 Cy: 0.00000 |
| Iz: 19.36467 Iy: 19.36467 J: 38.72935 |
| Sz: 4.84117 Sy: 4.84117 |
| Rz: 2.79330 Ry: 2.79330 Cw: 0.00000 |
|-----------------------------------------------------------------------------|
| MATERIAL INFO: |
| Fy: 42.000 Fu: 58.000 E: 29500.000 G: 11300.000 |
|-----------------------------------------------------------------------------|
| DESIGN PROPERTIES: |
| Member Length: 120.000 Lz: 120.000 Ly: 120.000 Lb: 0.000 |
| DESIGN PARAMETERS: |
| Kz: 1.000 Ky: 1.000 NSF: 1.000 |
|-----------------------------------------------------------------------------|
| CRITICAL SLENDERNESS: |
|-----------------------------------------------------------------------------|
| LC : 4 Actual : 42.960 Allowable : 300.000 Ratio : 0.143 |
|-----------------------------------------------------------------------------|
STAAD SPACE -- PAGE NO. 5
STAAD.Pro CODE CHECKING - (AISI S100-16) [LRFD] (v1.0)
********************************************************
ALL UNITS ARE IN "INCH" AND "KIP " (U.N.O.)
| - MEMBER: 1 (Contd.....) |
| |
|-----------------------------------------------------------------------------|
| Limit States | Load# |Location| Demand | Capacity |Ratio| Reference |
|--------------------|-------|--------|----------|----------|-----|-----------|
| Tension | - | - | - | 93.814 | - |Sec. D2 |
| Yielding | - | - | - | 93.814 | - |Sec. D2 |
| Rupture | - | - | - | 107.961 | - |Sec. D3 |
| Compression | 7 | 10.00 | -27.500 | 78.700 |0.349|Sec. E3 |
| Local Comp | 7 | 10.00 | -27.500 | 78.700 |0.349|Sec. E3 |
| Axial Comp | 7 | 10.00 | -27.500 | 79.259 |0.347|Sec. E2 |
| Bending | 8 | 60.00 | -90.000 | 181.828 |0.495|Sec. F3 |
| Major Local Bend | 8 | 60.00 | -90.000 | 181.828 |0.495|Sec. F3 |
| Minor Local Bend | - | - | - | 181.828 | - |Sec. F3 |
| CYL TUB Major | 8 | 60.00 | 90.000 | 221.286 |0.407|Sec. F2.3 |
| Shear | 8 | 0.00 | 1.500 | 29.708 |0.050|Sec. G2 |
| Major Shear (Z) | - | - | - | 29.708 | - |Sec. G2 |
| Minor Shear (Y) | 8 | 0.00 | 1.500 | 29.708 |0.050|Sec. G2 |
| Interaction | 4 | 60.00 | - | - |0.657|Eq. H1.2-1 |
| (Bend+Ten) Int1 | 8 | 60.00 | - | - |0.492|Eq. H1.1-1 |
| (Bend+Ten) Int2 | 8 | 60.00 | - | - |0.495|Eq. H1.1-2 |
| (Bend+Comp) | 4 | 60.00 | - | - |0.657|Eq. H1.2-1 |
| (Bend+Shear) Z | 8 | 60.00 | - | - |0.498|Sec. H2 |
|-----------------------------------------------------------------------------|
56. PARAMETER 2
57. CODE AISI 2016
58. METHOD ASD
59. FYLD 42 ALL
60. TRACK 2 ALL
61. CHECK CODE ALL
STEEL DESIGN
WARNING # 8 ~ The specified value of FU for member # 1 seems out of range.
Reset back to default value.
STAAD SPACE -- PAGE NO. 6
STAAD.Pro CODE CHECKING - (AISI S100-16) [ASD ] (v1.0)
********************************************************
ALL UNITS ARE IN "INCH" AND "KIP " (U.N.O.)
|-----------------------------------------------------------------------------|
| MEMBER: 1 SECTION:ST PIP E LEN: 120.000 LOC: 60.000 |
| STATUS: PASS RATIO: 0.995 REF: Eq. H1.2-1 LC: 4 |
|-----------------------------------------------------------------------------|
| DESIGN FORCES: |
| Location: 60.000 Criteria: Eq. H1.2-1 LC: 4 |
| Fx:(C) 22.500 Fy: 1.125 Fz: -0.000 |
| Mx: 0.000 My: -0.000 Mz: -67.500 |
|-----------------------------------------------------------------------------|
| SECTION PROPERTIES: |
| Ag: 2.48186 Az: 1.24093 Ay: 1.24093 |
| Cz: 0.00000 Cy: 0.00000 |
| Iz: 19.36467 Iy: 19.36467 J: 38.72935 |
| Sz: 4.84117 Sy: 4.84117 |
| Rz: 2.79330 Ry: 2.79330 Cw: 0.00000 |
|-----------------------------------------------------------------------------|
| MATERIAL INFO: |
| Fy: 42.000 Fu: 58.000 E: 29500.000 G: 11300.000 |
|-----------------------------------------------------------------------------|
| DESIGN PROPERTIES: |
| Member Length: 120.000 Lz: 120.000 Ly: 120.000 Lb: 0.000 |
| DESIGN PARAMETERS: |
| Kz: 1.000 Ky: 1.000 NSF: 1.000 |
|-----------------------------------------------------------------------------|
| CRITICAL SLENDERNESS: |
|-----------------------------------------------------------------------------|
| LC : 4 Actual : 42.960 Allowable : 300.000 Ratio : 0.143 |
|-----------------------------------------------------------------------------|
STAAD SPACE -- PAGE NO. 7
STAAD.Pro CODE CHECKING - (AISI S100-16) [ASD ] (v1.0)
********************************************************
ALL UNITS ARE IN "INCH" AND "KIP " (U.N.O.)
| - MEMBER: 1 (Contd.....) |
| |
|-----------------------------------------------------------------------------|
| Limit States | Load# |Location| Demand | Capacity |Ratio| Reference |
|--------------------|-------|--------|----------|----------|-----|-----------|
| Tension | - | - | - | 62.418 | - |Sec. D2 |
| Yielding | - | - | - | 62.418 | - |Sec. D2 |
| Rupture | - | - | - | 71.974 | - |Sec. D3 |
| Compression | 7 | 10.00 | -27.500 | 51.438 |0.535|Sec. E3 |
| Local Comp | 7 | 10.00 | -27.500 | 51.438 |0.535|Sec. E3 |
| Axial Comp | 7 | 10.00 | -27.500 | 51.804 |0.531|Sec. E2 |
| Bending | 8 | 60.00 | -90.000 | 120.977 |0.744|Sec. F3 |
| Major Local Bend | 8 | 60.00 | -90.000 | 120.977 |0.744|Sec. F3 |
| Minor Local Bend | - | - | - | 120.977 | - |Sec. F3 |
| CYL TUB Major | 8 | 60.00 | 90.000 | 139.481 |0.645|Sec. F2.3 |
| Shear | 8 | 0.00 | 1.500 | 19.545 |0.077|Sec. G2 |
| Major Shear (Z) | - | - | - | 19.545 | - |Sec. G2 |
| Minor Shear (Y) | 8 | 0.00 | 1.500 | 19.545 |0.077|Sec. G2 |
| Interaction | 4 | 60.00 | - | - |0.995|Eq. H1.2-1 |
| (Bend+Ten) Int1 | 8 | 60.00 | - | - |0.739|Eq. H1.1-1 |
| (Bend+Ten) Int2 | 8 | 60.00 | - | - |0.744|Eq. H1.1-2 |
| (Bend+Comp) | 4 | 60.00 | - | - |0.995|Eq. H1.2-1 |
| (Bend+Shear) Z | 8 | 60.00 | - | - |0.748|Sec. H2 |
|-----------------------------------------------------------------------------|
62. FINISH