Civil Engineering Reference
In-Depth Information
T
t
h
q
τ
l
t
=
t
d
A
l
q
τ
l
t
A
t
d
(a) ELEMENT IN SHEAR
FLOW ZONE
(b) SHEAR STRESS
ON ELEMENT A
Figure 7.1
Hollow box subjected to torsion
where
ρ
,ρ
t
=
:
mild steel ratio in the
- and
t
-directions, respectively,
f
,
f
t
=
stresses in mild steel in the
- and
t
-directions, respectively.
ρ
p
,
ρ
tp
=
prestressing steel ratio in the
- and
t
-directions, respectively,
f
p
,
f
tp
=
stresses in prestressing steel in the
- and
t
-directions, respectively.
In Equations
[
1
]
-
[
3
]
the steel ratios,
ρ
,
ρ
t
,
ρ
p
,
ρ
tp
, should be taken with respect to the
thickness of the shear flow zone
t
d
as follows:
A
p
o
t
d
ρ
=
(7.4)
A
t
st
d
ρ
t
=
(7.5)
A
p
p
o
t
d
ρ
p
=
(7.6)
A
tp
st
d
ρ
tp
=
(7.7)
where
A
,
A
p
=
:
total cross-sectional areas of mild steel and prestressing steel, respectively, in the
longitudinal direction;
A
t
,
A
tp
=
cross-sectional areas of one mild steel bar and one prestressing steel strand,
respectively, in the transverse or hoop direction;
p
o
=
perimeter of centerline of shear flow around a cross-section;
s
=
spacing of hoop steel along a member.
