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V. ASME NF 3000 1998 Pipe

Verify the design of a pipe section used for a beam member per the ASME NF 3000 1998 code.

Details

The simply supported beam is 50 inches long. The beam is loaded with a 1.5 kip concentrated load at midspan and a uniformly distributed load of 1 kip/in over the entire length.

The member is PIPS 120 pipe section with Grade A36 steel.

Validation

Maximum shear force, V = P 2 + w L 2 = 1.5 2 + 1.0 ( 50 ) 2 = 25.75 kips

Maximum moment, M = P L 4 + w L 2 8 = 1.5 ( 50 ) 4 + 1.0 ( 50 ) 2 8 = 331.25 in⋅kip

Slenderness ratio = (KL/r) = 9.72 < 300

Bending About Major Axis (Z-Axis)

Section is compact: O D t = 36.43 < 3 , 300 F y = 91.67

Allowable bending stress: Fb = 0.66×Fy = 23.76 ksi

Actual bending stress: f b t z = f b c z = M z I z ( O D 2 ) = 331.25 262 ( 12.75 2 ) = 8.06 ksi

Stress ratio: 0.339

Shear

From the reference, the shear area:

A y = 0.25 π r 2 4 - r 1 4 2 r 2 - r 1 2 3 r 2 3 - r 1 3
where
r1
=
inner radius
r2
=
outer radius

Shear area: Ay = 6.8 in2

Actual shear stress (at supports): fv = 25.75 / 6.8 = 3.78 ksi

Actual shear stress (at midspan): fv = 0.75 / 6.8 = 0.110 ksi

Allowable shear stress, Fv = 0.4×Fy = 14.4 ksi

Stress ratio: 3.78/14.4 = 0.263

Results

Table 1. Comparison of results
Parameter Hand Calculation STAAD.Pro Difference Comments
Slenderness ratio 9.72 9.72 none  
Allowable bending stress (ksi) 23.8 23.8 none  
Actual bending stress (ksi) 8.06 8.06 none
Critical stress ratio 0.339 0.339 none
Allowable shear stress (ksi) 14.4 14.4 none
Shear stress ratio 0.201 0.201 none

STAAD Input

The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\09 Steel Design\US\ASME\NF 3000-1998\ASME NF 3000 1998 Pipe.std is typically installed with the program.

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 17-Aug-18
END JOB INFORMATION
SET SHEAR
INPUT WIDTH 79
UNIT INCHES POUND
JOINT COORDINATES
1 0 0 0; 2 50 0 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.9e+007
POISSON 0.3
DENSITY 0.283
ALPHA 1.2e-005
DAMP 0.03
TYPE STEEL
STRENGTH FY 36000 FU 58000 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TABLE ST PIPS120
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 PINNED
2 FIXED BUT FX MY MZ
LOAD 1 LOADTYPE None  TITLE LOAD CASE 1
MEMBER LOAD
1 CON GY -1500 25 0
1 UNI GY -1000 0 50
PERFORM ANALYSIS
PARAMETER 1
CODE NF3000 1998
CMY 1 ALL
CMZ 1 ALL
CT 0.85 ALL
FU 58000 ALL
FYLD 36000 ALL
KY 0.85 ALL
KZ 0.85 ALL
UNT 50 ALL
UNB 50 ALL
MAIN 200 ALL
NSF 0.9 ALL
RATIO 1 ALL
TMAIN 300 ALL
UNB 25 ALL
UNT 25 ALL
TRACK 2 ALL
CHECK CODE ALL
FINISH

STAAD Output

                       STAAD.PRO CODE CHECKING - (  ASME NF3000-98)   v2.0
                       ********************************************
 ALL UNITS ARE - POUN INCH (UNLESS OTHERWISE Noted)
 MEMBER     TABLE       RESULT/   CRITICAL COND/     RATIO/     LOADING/
                          FX            MY             MZ       LOCATION
 =======================================================================
      1  ST   PIPS120                  (AISC SECTIONS)
                           PASS      NF-98-EQN-22      0.339         1
                        0.00 T          0.00     -331249.97       25.00
 |-----------------------------------------------------------------------------|
 | SLENDERNESS CHECK:    ACTUAL RATIO:   9.72 ALLOWABLE RATIO: 300.00          |
 | ALLOWABLE STRESSES:   (UNIT - POUN INCH)                                    |
 | AXIAL: 2.12E+04  FCZ: 2.38E+04  FCY: 2.38E+04  FTZ: 2.38E+04  FTY: 2.38E+04 |
 | SHEAR: 1.44E+04                                                             |
 | ACTUAL STRESSES: (UNIT - POUN INCH)                                         |
 | AXIAL: 0.00E+00  FBZ: 8.06E+03  FBY: 0.00E+00 SHEAR: 8.43E+01               |
 |-----------------------------------------------------------------------------|
 | SECTION PROPERTIES: (UNIT - INCH)                                           |
 | AXX:  13.70  AYY:   7.01  AZZ:   7.01  RZZ:  4.37  RYY:  4.37               |
 | SZZ:      41.10  SYY:      41.10                                            |
 |-----------------------------------------------------------------------------|
 | PARAMETER: (UNIT - POUN INCH)                                               |
 | KL/R-Z:  9.72   KL/R-Y:  9.72   UNL:   25.0   CMZ:  1.00   CMY:  1.00       |
 | CB: 1.00   FYLD: 36000.00   FU: 58000.00   NET SECTION FACTOR: 0.90         |
 | CT:  0.85   STEEL TYPE:  0.0  KS:1.000  KV:1.000  KBK:1.000                 |
 |-----------------------------------------------------------------------------|
 | CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS POUN-INCH)                      |
 | CLAUSE       RATIO  LOAD       FX        VY        VZ        MZ        MY   |
 | TENSION      0.000    0    0.00E+00       -         -         -         -   |
 | COMPRESSION  0.000    0    0.00E+00       -         -         -         -   |
 | COMP&BEND    0.339    1    0.00E+00       -         -    3.31E+05 0.00E+00  |
 | TEN&BEND     0.000    0    0.00E+00       -         -    0.00E+00 0.00E+00  |
 | SHEAR-Y      0.201    1        -     2.57E+04       -         -         -   |
 | SHEAR-Z      0.000    0        -          -    0.00E+00       -         -   |
 |-----------------------------------------------------------------------------|