Civil Engineering Reference
In-Depth Information
TABLE 6.6
Short Compression Member Buckling Coefficient
Steel Yield Stress (
F
y
)
(ksi)
KL
/
r
From Equation (6.36)
36
18
44
16
50
15
the value of
KL/r
that delineates elastic and inelastic stability and Equation 6.36 pro-
vides the value of
KL/r
that delineates inelastic and yielding behavior. The AREMA
(2008) strength criterion for axial compression members with steel yield strength of
50 ksi is shown in
Figure 6.11
with some other compression member design criteria.
6.3.2 S
ERVICEABILITY OF
A
XIAL
C
OMPRESSION
M
EMBERS
Limiting the compression member slenderness ratio based on effective length,
KL
,
to that of Equation 6.34 precludes the possibility of elastic buckling in order to
avoid sudden stability failures in steel railway superstructures. However, slender-
ness ratio,
L/r
, must also be limited to values that will preclude excessive vibration
or deflection, which is of particular concern for compression member stability (e.g.,
to avoid excessive secondary flexural compressive stress due to member curvature).
Fa AREMA
Fa CRC
SSRC1
SSRC2
SSRC3
Fa Euler CRC
Fa Euler AREMA
45,000
40,000
35,000
30,000
25,000
20,000
15,000
10,000
5000
0
0
20
40
60
80
100
120
140
160
180
200
kL
/
r
FIGURE 6.11
Compression member strength curves (
F
y
=
50 ksi).
