V. ASME NF 3000 1974 Angle
Verify the allowable stress and critical ratio of the brace members in a frame using the ASME NF 3000 1974 code.
Details
The forces due to loading in member 6 is 2,666.18 lbs (tension) and in member 7 is 7,104.23 lbs (compression). Members 6 and 7 are "truss" members (axial-only).
Both member 6 and 7 are L 80x60x10, grade A36 steel (Fy = 36 ksi, Fu = 58 ksi).
Assume a net section factor of 0.9, an effective length factor of 0.85, and Ct = 0.9.
Validation
Slenderness ratio (same for both members) using the minimum value of r: kL/rz = 0.85(93.726)/1.29 = 61.76
For member 6, kL/rz = 61.76 < 300
For member 7, kL/rz = 61.76 < 200
Axial Tension: Member 6 (per NF-74.2211)
Corrected area, Ac = Ct×Ax = 7.57 in2
Actual tensile stress = P/A = 2,666.18 / 7.57 = 352.2 psi
Allowable tensile stress (Tension capacity) = 0.6×Fy = 0.6×36 = 21.6 ksi
Critical ratio = 352.2/21,600 = 0.016
Axial Compression: Member 7 (NF-74.2213):
Actual compressive stress = P/A = 7,104.23 / 8.41 = 844.74 psi
| (NF-3322.2(e)(5) ) |
(kL/r)min < Cc', allowable compression stress, Fa = 17.2 ksi
Critical ratio = 844.74 / 17,200 = 0.049
Results
| Parameter | Hand Calculation | STAAD.Pro | Difference | Comments | |
|---|---|---|---|---|---|
| Member 6 (tension) | Slenderness ratio | 61.76 | 61.76 | none | |
| Actual tensile stress (psi) | 352 | 352 | none | ||
| Allowable tensile stress (psi) | 21,600 | 21,600 | none | ||
| Critical ratio | 0.016 | 0.016 | none | ||
| Member 7 (compression) | Slenderness ratio | 61.76 | 61.76 | none | |
| Actual tensile stress (psi) | 845 | 845 | none | ||
| Allowable tensile stress (psi) | 17,200 | 17,200 | none | ||
| Critical ratio | 0.049 | 0.049 | none | ||
STAAD Input
The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\09 Steel Design\US\ASME\ASME NF 3000 1974 Angle.std is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 26-Aug-18
END JOB INFORMATION
SET SHEAR
INPUT WIDTH 79
UNIT INCHES POUND
JOINT COORDINATES
1 0 0 0; 2 60 0 0; 3 120 0 0; 4 0 72 0; 5 120 72 0; 6 60 72 0;
MEMBER INCIDENCES
1 1 4; 2 4 6; 3 6 5; 4 5 3; 5 6 2; 6 1 6; 7 6 3;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.9e+07
POISSON 0.3
DENSITY 0.283
ALPHA 1.2e-05
DAMP 0.03
TYPE STEEL
STRENGTH FY 36000 FU 58000 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 5 TABLE ST W8X48
6 7 TABLE ST L806010
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 TO 3 FIXED
MEMBER TRUSS
6 7
LOAD 1 LOADTYPE None TITLE LOAD CASE 1
JOINT LOAD
4 FX 7500
6 FY -10000
PERFORM ANALYSIS
PRINT MEMBER PROPERTIES LIST 6 7
SECTION 0 0.25 0.5 0.75 1 MEMB 6 7
PRINT MEMBER SECTION FORCES LIST 6 7
PRINT MEMBER FORCES LIST 6 7
PRINT MEMBER STRESSES LIST 6
PARAMETER 1
CODE NF3000 1974
CMY 1 ALL
CMZ 1 ALL
CT 0.9 ALL
FU 58000 ALL
FYLD 36000 ALL
KY 0.85 ALL
KZ 0.85 ALL
UNT 60 ALL
UNB 60 ALL
MAIN 200 ALL
NSF 0.9 ALL
RATIO 1 ALL
TMAIN 300 ALL
TRACK 2 ALL
CHECK CODE ALL
FINISH
STAAD Output
6 ST L806010 (AISC SECTIONS) PASS NF-74.2211 0.016 1 -2666.18 T 0.00 0.00 0.00 |-----------------------------------------------------------------------------| | SLENDERNESS CHECK: ACTUAL RATIO: 72.65 ALLOWABLE RATIO: 300.00 | | ALLOWABLE STRESSES: (UNIT - POUN INCH) | | AX.TENS: 2.16E+04 COMPRESS:1.72E+04 | | | | ACTUAL STRESSES: (UNIT - POUN INCH) | | AX.TENS: 3.52E+02 COMPRESS:0.00E+00 | |-----------------------------------------------------------------------------| | SECTION PROPERTIES: (UNIT - INCH) | | AXX: 8.41 AYY: 3.33 AZZ: 2.50 RZZ: 1.29 RYY: 2.81 | | SZZ: 5.16 SYY: 11.99 | |-----------------------------------------------------------------------------| | PARAMETER: (UNIT - POUN INCH) | | KL/R-Z: 61.76 KL/R-Y: 28.34 UNL: 60.0 CMZ: 1.00 CMY: 1.00 | | CB: 0.00 FYLD: 36000.00 FU: 58000.00 NET SECTION FACTOR: 0.90 | | 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 0.016 1 2.67E+03 - - - - | | COMPRESSION 0.000 0 0.00E+00 - - - - | | COMP&BEND 0.000 0 0.00E+00 - - 0.00E+00 0.00E+00 | | TEN&BEND 0.016 1 2.67E+03 - - 0.00E+00 0.00E+00 | | SHEAR-Y 0.000 0 - 0.00E+00 - - - | | SHEAR-Z 0.000 0 - - 0.00E+00 - - | |-----------------------------------------------------------------------------| 7 ST L806010 (AISC SECTIONS) PASS NF-74.2213 0.049 1 7104.23 C 0.00 0.00 0.00 |-----------------------------------------------------------------------------| | SLENDERNESS CHECK: ACTUAL RATIO: 61.76 ALLOWABLE RATIO: 200.00 | | ALLOWABLE STRESSES: (UNIT - POUN INCH) | | AX.TENS: 2.16E+04 COMPRESS:1.72E+04 | | | | ACTUAL STRESSES: (UNIT - POUN INCH) | | AX.TENS: 0.00E+00 COMPRESS:8.45E+02 | |-----------------------------------------------------------------------------| | SECTION PROPERTIES: (UNIT - INCH) | | AXX: 8.41 AYY: 3.33 AZZ: 2.50 RZZ: 1.29 RYY: 2.81 | | SZZ: 5.16 SYY: 11.99 | |-----------------------------------------------------------------------------| | PARAMETER: (UNIT - POUN INCH) | | KL/R-Z: 61.76 KL/R-Y: 28.34 UNL: 60.0 CMZ: 1.00 CMY: 1.00 | | CB: 0.00 FYLD: 36000.00 FU: 58000.00 NET SECTION FACTOR: 0.90 | | 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 0.049 1 7.10E+03 - - - - | | COMP&BEND 0.049 1 7.10E+03 - - 0.00E+00 0.00E+00 | | TEN&BEND 0.000 0 0.00E+00 - - 0.00E+00 0.00E+00 | | SHEAR-Y 0.000 0 - 0.00E+00 - - - | | SHEAR-Z 0.000 0 - - 0.00E+00 - - | |-----------------------------------------------------------------------------|