fundamentals of engineering supplied-reference handbook - Ventech!

♦
50.0 1.0
10.0
5.0
3.0
0.9
2.0
1.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
G A
Table C – C.2.1. K VALUES FOR COLUMNS
Theoretical K value
Recommended design
0.5 0.7 1.0 1.0 2.0 2.0
value when ideal conditions
are approximated
0.65 0.80 1.2 1.0 2.10 2.0
K G G
B
A
0.8
0.7
0.6
0.5
50.0
10.0
5.0
3.0
2.0
1.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
130
100.0
50.0
30.0
20.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0
20.0
10.0
5.0
4.0
SIDEWAY INHIBITED SIDEWAY UNINHIBITED
K
3.0
2.0
1.5
1.0
G B
100.0
50.0
30.0
20.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0
CIVIL ENGINEERING (continued)
Figure C – C.2.2.
ALIGNMENT CHART FOR EFFECTIVE LENGTH OF COLUMNS IN CONTINUOUS FRAMES
♦
The subscripts A and B refer to the joints at the two ends of the column section being considered.
G is defined as
Σ ( I c /Lc
)
G =
Σ I /L
( )
g
g
in which Σ indicates a summation of all members rigidly connected to that joint and lying on the plane in
which buckling of the column is being considered. Ic is the moment of inertia and Lc the unsupported length of
a column section, and Ig is the moment of inertia and Lg the unsupported length of a girder or other
restraining member. Ic and Ig are taken about axes perpendicular to the plane of buckling being considered.
For column ends supported by but not rigidly connected to a footing or foundation, G is theoretically infinity,
but, unless actually designed as a true friction-free pin, may be taken as "10" for practical designs. If the
column end is rigidly attached to a properly designed footing, G may be taken as 1.0. Smaller values may be
used if justified by analysis.
♦ Manual of Steel Construction: Allowable Stress Design, American Institute of Steel Construction, 9th ed., 1989.