Civil Engineering Reference
In-Depth Information
Table 13.2
Axial rigidity assignments of the SAP2000 model
Steel
Concrete
A
s
mm
2
(in
2
)
E
c
ksi (GPa)
A
c
mm
2
(in
2
)
Member
E
s
ksi (GPa)
Comments
2-4
E
s
=
29,000 (200)
A
s
=
4813 (7.46)
E
c
=
4490 (30,960)
b
w
kd
=
161,740 (250.7)
Tension chord
4-5
1-3
E
s
=
29,000 (200)
A
′
=
4051 (6.28)
ψ
e
E
c
=
3680 (25,373)
b
w
kd
=
161,740 (250.7)
Compression chord
3-4
E
s
=
29,000 (200)
N
h
A
sh
=
1584 (2.46)
E
c
=
4490 (30,960)
=
165,350 (256.3)
Active hoop steel including
tension stiffening
(4
c
+
2 )
d N s
h
1-5
-
-
E
c
=
4490 (30,960)
Concrete strut in arch
mechanism
0.375
cos
η
b
jd
=
144,645 (224.2)
w
α
1-4
-
-
E
c
=
4490 (30,960)
Concrete strut in truss
mechanism
0.5 1
0.423 tan
2
b jd
w
−
η
(
)
=
145,390 (220.7)
+
α
3-5
-
-
E
c
=
4490 (30,960)
Concrete strut in truss
mechanism
0.5 1
0.577 tan
2
−
η
b jd
w
(
)
=
131,100 (203.2)
+
α
A
c
, the area of concrete in compression;
b
w
, the beam width;
d
, the effective depth of the beam from the extreme concrete compression iber to the centroid of the
tension steel;
s
, the stirrup spacing;
j
, the internal lever arm coeficient, which, in lieu of a more precise analysis, may be taken as
j
=
0.9;
E
c
,Young's modulus for concrete;
E
s
, Young's modulus for steel;
A
s
, the area of longitudinal tension reinforcement;
A
′
, the area of compression reinforcement;
A
sh
, the area of one set of stirrups;
k
, the elastic compression zone coeficient
′
d
′
ρ
2
2
L
k
(
′
)
n
2
n
(
′
)
n
;
=
ρ
+
ρ
+
ρ
+
+
ρ
+
ρ
L
L
L
L
L
d
ψ
e
, strain compatibility coeficient, in lieu of a more precise analysis, 0.6 is recommended;
N
h
, integer part of active hoops in truss mechanism
N
1);
α
,
h
=
int(
L s
/ −
the corner-to-corner diagonal angle.
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