Civil Engineering Reference
In-Depth Information
Transverse Steel for Vertical Walls
Transverse steel in the vertical walls is contributed by both shear and torsion:
A
t
s
+
1
2
A
s
1
2
(1
977 mm
2
2
=
0
.
303
+
.
347)
=
0
.
/
mm (0
.
0384 in
.
/
in
.
)
A
t
s
+
min
=
1
2
A
s
0
.
172(502)
413
209 mm
2
2
=
0
.
/
mm (0
.
00823 in
.
/
in
.
)
977 mm
2
2
<
0
.
/
mm (0
.
0384 in
.
/
in
.
)OK
Select two layers of No. 5 bars in each vertical wall at 305 mm (12 in.) spacing:
2(200)
305
2
977 mm
2
2
=
1
.
311 mm (0
.
0516 in
.
/
in
.
)
>
0
.
/
mm (0
.
0384 in
.
/
in
.
)OK
Transverse Steel for Horizontal Walls
Transverse steel in the horizontal walls is contributed by torsion only:
A
t
s
=
303 mm
2
2
0
.
/
mm (0
.
0119 in
.
/
in
.
)
Select two layers of No. 3 bars in each horizontal wall at 305 mm (12 in.) spacing:
2(71)
305
=
466 mm
2
2
303 mm
2
0
.
/
mm (0
.
0183 in
.
/
in
.
)
>
0
.
/
mm
.
OK
The transverse steel in the top wall should be added to the flexural steel required in the top
flange acting as a transverse continuous slab.
Arrangement of Reinforcing Bars
The arrangement of the reinforcing bars for shear and torsion is shown in Figure 2.20. This
steel arrangement could be conservatively used throughout the length of the girder.
2.4 Comments on the Equilibrium (Plasticity) Truss Model
The equilibrium (plasticity) truss model presented in this chapter summarizes the major
advances in reinforced concrete theory achieved during the 1970s. A milestone in this devel-
opment was the adoption of this model by the 1978 European Code (CEB-FIP, 1978). This
model was incorporated into the 1995 ACI Code (ACI 318-95).
However, serious weaknesses exist in these provisions due to its historical limitations.
The difficulties stemmed primarily from a lack of understanding of the strain compatibility
condition for shear and torsion, as well as the biaxial behavior of reinforced concrete 2-D
elements. These problems had been extensively studied in the 1980s, 1990s up to the present
time. The new information is presented in Chapters 4-8.
