Civil Engineering Reference
In-Depth Information
q
f
bx
+
f
by
f
a
6F
y
+
≤
1
:
0
(3.85)
0
:
F
b
where the undefined terms used are as defined by the AISC Specification for the
Design, Fabrication, and Erection of Structural Steel for Buildings.
When f
a
/F
a
≤
0.15, the following formula may be used in lieu of the fore-
going two formulas.
q
f
bx
+
f
by
f
a
F
y
+
≤
:
1
0
(3.86)
F
b
′
e
are appropriate
for f
bx
and f
by
. If different values are applicable, the following general formula
should be used instead of
Equation (3.84)
:
Equation (3.84)
assumes that the same values of C
m
and F
t
0
1
0
1
2
2
@
A
@
A
C
my
f
by
C
mx
f
bx
1
+
f
a
F
ex
f
a
F
ey
−
1
−
′
′
f
a
F
a
+
≤
1
:
0
(3.87)
F
b
Member Slenderness
The slenderness of the steel section is defined by (Kl/r), where l is the member
length, k is the buckling factor and r is the radius of gyration, which is also
applied for cylindrical compression. Members should be in accordance with
the America Institute of Steel Construction (AISC). To obtain the buckling fac-
tor, the joint end should be defined by its fixity and the joint movement. More-
over, a rational definition of the reduction factor should consider the character
of the cross-section and the loads acting on the member. In lieu of such an ana-
lysis, the following values may be used.
Combined Axial Tension and Bending
Cylindrical members subjected to combined tension and bending should be pro-
portioned to satisfy
Equation (3.85)
at all points along their length, where f
bx
and f
by
are the computed bending tensile stresses.
Axial Tension and Hydrostatic Pressure
The hydrostatic pressure is usually applied to the member at the sea mean water
level. So the following interaction equation applies if the member is under
longitudinal tensile stresses and hoop compressive stresses at the same time:
A
2
B
2
+
+
2
ν j
A
j
B
≤
1
:
0
(3.88)
Search WWH ::
Custom Search