# V. AISC LRFD - Select Wide Flange 1

To select the optimum ASTM A992 W-shape with a design flexural strength of 500 kip-ft.

## Reference

AISC Load Factor Resistance Design, 3rd Edition, Table 5.2, , page 5-50.

## Problem

Beam is bent about its strong axis, and is continuously braced.

 Fy = 50 ksi

 Length = 30 ft

 w = 4.44 kip/ft (equiv. of 500 ft·kip design moment)

## Comparison

Table 1. Comparison of results
Optimum section W24x55 W24x55 none
Design strength, ϕbMz (ft·kips) 506 502.5 (*) <1%

* Calculated as MZ envelope value divided by the MZ ratio:

499.95 ft·kips/0.995 = 502.5 ft·kips

Note: Fully braced condition can be achieved by setting the UNT parameter equal to 1.0 inch.

The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\09 Steel Design\US\AISC\AISC LRFD - Select Wide Flange 1.STD is typically installed with the program.

``````STAAD SPACE BENDING CAPACITY PER AISC LRFD 3RD ED
START JOB INFORMATION
ENGINEER DATE 23-Sep-18
END JOB INFORMATION
*
*  TABLE 5.2, PAGE 5-40, AISC LRFD 3RD ED.
*  OBJECTIVE : TO SELECT THE MOST OPTIMUM SECTION WITH A DESIGN
*  FLEXURAL STRENGTH OF 500 KIP-FT.
*  FOR A FULLY BRACED BEAM, PER ABOVE REFERENCE, IT SHOULD BE
*  A W24X55
*
* 500 KIP-FT IS EQUAL TO AN APPLIED LOAD OF 4.444 KIP/FT ON
* A SIMPLY SUPPORTED BEAM
*
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 30 0 0;
MEMBER INCIDENCES
1 1 2;
MEMBER PROPERTY AMERICAN
1 TABLE ST W12X26
UNIT INCHES KIP
DEFINE MATERIAL START
ISOTROPIC MATERIAL1
E 29000
POISSON 0.3
END DEFINE MATERIAL
UNIT FEET KIP
CONSTANTS
MATERIAL MATERIAL1 ALL
SUPPORTS
1 PINNED
2 FIXED BUT MZ
1 UNI GY -4.444
PERFORM ANALYSIS
UNIT INCHES KIP
PARAMETER 1
CODE LRFD
* FULLY BRACED CONDITION IS ACHIEVED WITH A UNT OF 1.0 INCH
UNT 1 ALL
MAIN 1 ALL
FYLD 50 ALL
CB 0 ALL
TRACK 2 ALL
SELECT ALL
FINISH
``````

```                     STAAD.PRO MEMBER SELECTION - (LRFD 3RD EDITION)   v1.0
***********************************************
|--------------------------------------------------------------------------|
|                                                    Y        PROPERTIES   |
|*************                                       |        IN INCH UNIT |
|            *  |=============================|   ===|===     ------------ |
|MEMBER   1  *  |  AISC SECTIONS              |      |        AX=0.1620E+2 |
|            *  | ST  W24X55                  |      |   --Z  AY=0.9322E+1 |
|DESIGN CODE *  |                             |      |        AZ=0.4720E+1 |
| LRFD 2001  *  ===============================   ===|===     PY=0.1330E+2 |
|            *                                                PZ=0.1340E+3 |
|            *  |&lt;---LENGTH (FT)=   30.00 --->|               RY=0.1340E+1 |
|*************                                                RZ=0.9129E+1 |
|                                                                          |
|                499.9 (KIP-FEET)                                          |
|PARAMETER        |               L1  L1  L1                  CAPACITIES   |
|IN KIP  INCH     |                                           IN KIP  INCH |
|---------------  +           L1              L1              -------------|
| KL/R-Y= 268.60  |                                           PNC=0.4791E+2|
| KL/R-Z=  39.44  +       L1                      L1          pnc=0.0000E+0|
| UNL   =   1.00  |                                           PNT=0.7290E+3|
| CB    =   1.14  +   L1                              L1      pnt=0.0000E+0|
| PHIC  =   0.85  |                                           MNZ=0.6030E+4|
| PHIB  =   0.90  +                                           mnz=0.5999E+4|
| FYLD  =  50.00  |L0                                     L0  MNY=0.5604E+3|
| NSF   =   1.00  +---+---+---+---+---+---+---+---+---+---|   mny=0.0000E+0|
| DFF =     0.00 -27.8                                        VN =0.2517E+3|
| dff =     0.00               ABSOLUTE MZ ENVELOPE           vn =0.0000E+0|
|                                                                          |
|                      MAX FORCE/ MOMENT SUMMARY  (KIP-FEET)               |
|                      -------------------------                           |
|                                                                          |
|                AXIAL      SHEAR-Y    SHEAR-Z    MOMENT-Y    MOMENT-Z     |
|                                                                          |
|      VALUE       0.0        66.7        0.0         0.0       499.9      |
|   LOCATION       0.0         0.0        0.0         0.0        15.0      |
|                                                                          |
|**************************************************************************|
|*                                                                        *|
|*                         DESIGN SUMMARY  (KIP-FEET)                     *|
|*                         --------------                                 *|
|*                                                                        *|