V. AISC LRFD - Wide Flange Compression Capacity 1

To determine the capacity of W14X132 column in axial compression.

Reference

Hand calculation using the following reference:

AISC Load Factor Resistance Design, 3rd Edition, Example 4.1, case (a), page 4-7.

Problem

The column is braced at its ends for both axes.

F_y =50 ksi

Length = 30 ft

Hand Calculation

Net section = 0.795(3.75 in.²) = 2.98 in.²

ϕ P_{n} = {\begin{matrix} ϕ_{t} F_{y} A_{g} = 0.9 (36 k s i) (3.75 {i n .}^{2}) = 121.5 k \\ ϕ_{t} F_{u} A_{e} = 0.75 (58 k s i) (2.98 {i n .}^{2}) = 129.6 k \end{matrix}

Comparison

The reported STAAD.Pro value is based on the term PNT in the STAAD.Pro output..

表 1. Comparison of results
Result Type		Theory	STAAD.Pro	Difference
Design strength (kips)		844	843.02	none

STAAD Input

The file C:\Users\Public\Public Documents\STAAD.Pro 2023\Samples \Verification Models\09 Steel Design\US\AISC\AISC LRFD - Wide Flange Compression Capacity 1.STD is typically installed with the program.

STAAD SPACE AXIAL COMPRESSION CAPACITY PER AISC LRFD 3RD ED
START JOB INFORMATION
ENGINEER DATE 23-Sep-18
END JOB INFORMATION
*
*  EXAMPLE PROBLEM 4.1, CASE (A), PAGE 4-7, AISC LRFD 3RD ED.
*  CAPACITY (PNC) SHOULD BE ABOUT 844 KIPS
*
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 0 30 0;
MEMBER INCIDENCES
1 1 2;
MEMBER PROPERTY AMERICAN
1 TABLE ST W14X132
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 FY MX MZ
LOAD 1
JOINT LOAD
2 FY -840
PERFORM ANALYSIS
UNIT INCHES KIP
PARAMETER 1
CODE LRFD
FYLD 50 ALL
TRACK 1 ALL
CHECK CODE ALL
FINISH

STAAD Output

                         STAAD.Pro CODE CHECKING - (LRFD 3RD EDITION)   v1.0
                         ***********************
 ALL UNITS ARE - KIP  INCH (UNLESS OTHERWISE Noted)
 MEMBER     TABLE       RESULT/   CRITICAL COND/     RATIO/     LOADING/
                          FX            MY             MZ       LOCATION
 =======================================================================
      1  ST   W14X132                  (AISC SECTIONS)
                           PASS     LRFD-H1-1A-C       0.996         1
                      840.00 C          0.00           0.00        0.00
 +---------------------------------------------------------------------+
 | DESIGN STRENGTHS FOR MEMBER     1       UNITS - KIP IN              |
 | PNC=  843.02  PNT= 1746.00  MNZ= 9138.93  MNY= 5032.65  VN=  256.00 | 
 +---------------------------------------------------------------------+