Civil Engineering Reference
In-Depth Information
where
A
v
is the area (in
2
) of the vertical shear reinforcement within the
spacing
s
v
and
f
y
is the strength of the shear reinforcement which should not
be taken as exceeding 60 000 lb/in
2
(410 N/mm
2
).
Where the design shear force
V
u
exceeds φ
V
c
vertical shear reinforcement
shall be provided to carry the excess shear. The contribution
V
s
of this shear
reinforcement is given by:
V
s
=(
A
v
f
y
d
/
s
v
)
where the symbols are as defined for Eqns (1.32) and (1.31).
Combining Eqns (1.29), (1.30) and (1.33),
(
A
v
/
bs
v
) > ((
V
u
/
φ)-
V
c
)
/bdf
y
Irrespective of the values obtained from Eqns (1.34) or (1.33),
A
v
/bs
v
shall
not be taken as less than 0.0015; the spacing
s
v
shall not exceed
d/
5 nor 18
in (450 mm). In addition, nominal horizontal web reinforcement must also
be provided, such that
A
h
/bs
h
is not less than 0.0025 and the spacing
s
h
of
this horizontal reinforcement shall not exceed
d/
3 nor 18 in (450 mm).
(1.33)
(1.34)
1.7
Canadian Code CAN3-A23.3-M84
1.7.1
Flexural strength
For flexural design the Canadian Code CAN3-A23.3-M84 (1984) defines a
deep beam as a beam in which the ratio of the clear span
l
o
to the overall
depth
h
is less than the limits in Eqn (1.35):
simple spans
:
l
o
/h<
1.25
(1.35a)
continuous spans
:
l
o
/h<
2.5
(1.35b)
1.7.1.1
Minimum tension reinforcement
The main steel ratio ρ shall not be
less than ρ
min
of Eqn (1.36)
ρ
min
=1.4
/f
y
(1.36)
where ρ
min
=
A
s
/db, A
s
is the area of the main tension reinforcement, b is the
beam width,
d
is the effective depth and
f
y
is the steel strength. (Note: unlike
the ACI Code, the Canadian Code is in SI units)
1.7.1.2
Web reinforcement
A system of orthogonal web reinforcement is
required, with bars in each face. The minimum areas of the vertical and
horizontal reinforcement shall satisfy Eqn (1.37)
A
v
/bs
v
>
0.2%
(1.37a)
>
A
h
/bs
h
0.2%
(1.37b)
