V. IS 801-Pipe subject to axial compression and bending
Verification example for a cold-formed beam subject to axial compression and bending moment according to IS:801-1975.
Details
The section used is an ST 101.6x2.6CHS (pipe) section. The beam is a 6 m span subject to axial compression and bending moments. Both ends of the span are fixed.
Material properties:
- E = 203,400 MPa
- Fy = 353.0 MPa
Design forces:
- P = ±2.5 kN
- Mz = 3.88 kN·m
- Vy = 3.88 kN
Section properties:
- Outer diameter, OD = 101.6 mm
- Thickness, t = 2.6 mm
- Area, A = 8.09 cm2
- Moment of inertia about the major axis, Izz = 99.1 cm3
- Section modulus about the major axis, Zxx = 19.51 cm3
Calculations
Verification
Compressive Stress
Radius of gyration,
Allowable compression stress:
Therefore, the allowable compressive stress:
Stress ratio in compression: 3.09 / 35.65 = 0.087
Bending Stress
Avg. diameter = 101.6 mm - 2.6 mm = 99.0 mm
Per Cl. 6.8, the maximum allowable stress in bending:
F = 0.6 × Fy = 0.6 × 353.1 = 211.9
MPa
Actual bending stress:
Tensile Stress
Allowable tension stress:
F = 0.6 × Fy = 0.6 × 353.1 = 211.9
MPa
Calculation of Allowable Shear Stress
Allowable shear stress:
Fv = 0.4 × Fy = 0.4 × 353.1 = 141.2
MPa
Shear area:
Stress ration in shear: 9.35 / 141.2 = 0.066
Results
| Result Type | Reference | STAAD.Pro | Difference | Comments |
|---|---|---|---|---|
| Allowable compression stress (MPa) | 35.65 | 35.660 | negligible | |
| Actual compression stress (MPa) | 3.09 | 3.090 | none | |
| Compression stress ratio | 0.087 | 0.087 | none | |
| Allowable bending stress (MPa) | 211.9 | 211.854 | negligible | |
| Actual bending stress (MPa) | 198.9 | 198.857 | negligible | |
| Allowable tensile stress (MPa) | 211.9 | 211.854 | negligible | |
| Actual tensile stress (MPa) | 3.09 | 3.090 | none | |
| Tension stress ratio | 0.015 | 0.015 | none | |
| Allowable shear stress (MPa) | 141.2 | 141.236 | negligible | |
| Actual shear stress (MPa) | 9.349 | 9.349 | none | |
| Shear stress ratio | 0.066 | 0.066 | none |
Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2026\Samples \Verification Models\09 Steel Design\India\IS 801-Pipe subject to axial compression and bending.STD is typically installed with the program.
The following design
parametersdesign parameters are
used:
- The effect of cold work of forming strengthening is not considered by specifying
the parameter
CWY 0
STAAD
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 02-Apr-19
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 6 0 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.05e+08
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-05
DAMP 0.03
TYPE STEEL
STRENGTH RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY COLDFORMED AUSTRALIAN
1 TABLE ST 101.6x2.6CHS
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 2 FIXED
LOAD 1 LOADTYPE None TITLE LOAD CASE 1(DL)
MEMBER LOAD
1 UNI GY -0.169
1 CON GX -5
LOAD 2 LOADTYPE None TITLE LOAD CASE 2
MEMBER LOAD
1 UNI GY -1.01
LOAD 3 LOADTYPE None TITLE LOAD CASE 3
MEMBER LOAD
1 UNI GY 1.893
LOAD 4 LOADTYPE None TITLE LOAD CASE 4
MEMBER LOAD
1 UNI GY -0.158
LOAD COMB 5 COMBINATION LOAD CASE 5
1 1.0 2 1.0
LOAD COMB 6 COMBINATION LOAD CASE 6
1 0.75 3 0.75
LOAD COMB 7 COMBINATION LOAD CASE 7
1 0.75 2 0.75 4 0.75
PERFORM ANALYSIS
LOAD LIST 5 TO 7
PARAMETER 1
CODE IS801
TRACK 2 ALL
CWY 0 ALL
CHECK CODE ALL
FINISH
Output
STAAD.Pro CODE CHECKING - ( IS:801 ) v3.0
***********************
ALL UNITS ARE IN - METE KN (U.N.O.)
|-----------------------------------------------------------------------------|
| MEMBER: 1 SECTION: 101.6X2.6CHS LEN: 6.000 LOC: 0.000 |
| STATUS: PASS RATIO: 0.951 REF: 6.7.1b LC: 6 |
|-----------------------------------------------------------------------------|
| DESIGN FORCES: |
| Fx:(C) 1.875 Fy: -3.879 Fz: 0.000 |
| Mx: 0.000 My: 0.000 Mz: -3.879 |
|-----------------------------------------------------------------------------|
| SECTION PROPERTIES: (Unit: CM) |
| Ag: 8.09000 Az: 4.14956 Ay: 4.14956 |
| Cz: 5.08000 Cy: 5.08000 Z0: 0.00000 |
| Iz: 99.10001 Iy: 99.10001 J: 198.20002 |
| Sz: 19.50788 Sy: 19.50788 |
| Rz: 3.49996 Ry: 3.49996 Cw: 639.09555 |
|-----------------------------------------------------------------------------|
| MATERIAL INFO: (Unit: MPa) |
| Fy: 353.090 Fu: 449.993 E: 203404.356 G: 77968.401 |
| Fya(compression): 353.090 Fya(bending): 353.090 |
|-----------------------------------------------------------------------------|
| DESIGN PROPERTIES: |
| Member Length: 6.000 Lz: 6.000 Ly: 6.000 Lb: 6.000 |
| DESIGN PARAMETERS: |
| Kz: 1.000 Ky: 1.000 NSF: 1.000 Cb: 0.000 |
|-----------------------------------------------------------------------------|
| CRITICAL SLENDERNESS: |
| Actual: 171.431 Allowable: 200.000 Ratio: 0.857 |
|-----------------------------------------------------------------------------|
| CHECKS: | Stresses | |
| | Loc. | Demand | L/C | Actual | Allow |Ratio | Ref CL |
| |(MET) |(KN-MET)| | (MPa) | (MPa) | | |
|--------------|------|--------|------|----------|----------|------|----------|
| Tension | 3.500| -2.50| 5| 3.090 | 211.854 | 0.015| 6.1 |
| Compression | 0.000| 2.50| 5| 3.090 | 35.660 | 0.087| Cl.6.8 |
| BendZComp | 0.000| 3.88| 6| 198.857 | 211.854 | 0.939| 6.3 |
| BendZTens | 0.000| 3.88| 6| 198.857 | 211.854 | 0.939| 6.3 |
| BendUnbraced | - | - | - | - | 0.000 | - | |
| BendYComp | - | - | - | - | 211.854 | - | 6.3 |
| BendYTens | - | - | - | - | 211.854 | - | 6.3 |
| Shear Z | - | - | - | - | 141.236 | - | 6.4.1 |
| Shear Y | 0.000| -3.88| 6| 9.349 | 141.236 | 0.066| 6.4.1 |
| Axial+Bend | 0.000| - | 6| - | - | 0.951| 6.7.1b |
| Bend+Shear | 0.000| - | 6| - | - | 0.066| 6.4.3 |
|-----------------------------------------------------------------------------|
| Effective Section Properties:(cm) |
| Ae: 8.090 SzTop: 19.508 SzBot: 19.508 SyLeft: 19.508 SyRight: 19.508 |
| Intermediate Results: Cb = 0.000 |
|-----------------------------------------------------------------------------|
NOTE: Torsion has not been considered in the design.