Example E.4B W-shape compression member (moment frame)

The results are generated with SDC Verifier 3.6 and calculated with FEMAP v11.0.0

Task:

Using the effective length method, determine the available strength of the column shown subject to the same gravity loads shown in Exmple E.4A with the column pinned at the base about x-x axis. All other assumptions remain the same.

Solution:

As determined in Example E.4A, for column segment B-C between the roof and the floor, the column stern is adequate.

As determined in Example E.4A, for column segment A-B between the floor and the foundation,

    Gtop = 1.62

At the base,

    Gbottom = 10 (pinned) from AISC Specification Commentary Appendix 7, Section 7.2

Note: this is the only change in the analysis.

From the alignment chart, AISC Specification Commentary Figure C-A-7.2, K is approximayely equal to 2. Because the column available strength tables are based on effectiove length, KL, about the y-y axis, effective column length of the segment A-B for use in the table is:

Interpolate the available strength of the W14&£215;82 from AISC Manual Table 4-1.

Example from AISC Design Examples

Material summary

Properties Summary

1..W14×82

Geometry Property Value
Height 1.19
Width 0.84
h 1.19
a 0.84
b 0.84
c 0.07
d 0.04
t 0.07

2..W24×55

Geometry Property Value
Height 1.97
Width 0.58
h 1.97
a 0.58
b 0.58
c 0.04
d 0.03
t 0.04

2..W18×50

Geometry Property Value
Height 1.50
Width 0.62
h 1.50
a 0.62
b 0.62
c 0.05
d 0.03
t 0.05

FEM Loads and Constraint

1..Dead load

2..Live load

Constraint

1.. Supports

Check 1..ANSI / AISC LRFD 360-10

Axial check

All (LS1, 1..AB)

Comparing results of calculation in SDC Verifier and in Example E.4B we can see that values completely match. The available strength in axial compression is 862 kips.