Civil Engineering Reference
In-Depth Information
Figure 1.3
Meanings of symbols
A
r
.
h
a
,
x
,
y
r,
θ
r
, φ (after CIRIA, 1977)
contribution to the shear capacity; for a beam with or thogonal web
reinforcement; it can also be tabulated for various steel ratios and
x
e
/
h
a
ratios. In other words, for a beam with orthogonal web
reinforcement, Eqn (1.11) can be expressed as Eqn (1.12), which is
more convenient to use in design:
V/bh
a
<λ
1
v
x
+ß(
v
;
ms
+
v
wh
+
v
wv
)
where λ
1
is λ
1
in Eqn (1.11), v
x
is the concrete shear stress parameter,
as tabulated in Table 4 of the CIRIA Guide for various values of
f
cu
and
the
x
e
/h
a
ratio; ß is 1.0 for deformed bars and 0.4 for plain round bars;
v
ms
is the main steel shear stress parameter, as tabulated in Table 6 of
the CIRIA Guide for various values of the main steel ratio and the
x
e
/
h
a
ratio;
v
wh
is the horizontal web steel shear stress parameter, as
tabulated in Table 7 of the CIRIA Guide for various values of the
horizontal web steel ratio and the
x
e
/
h
a
ratio; and
v
wv
is the vertical web
steel shear stress parameter, as tabulated in Table 8 of the CIRIA Guide
for various values of the vertical web steel ratio and the
x
e
/h
a
ratio.
(1.12)
Step 4:
From the calculations in step 3, check the total contribution of the
(main and web) reinforcement to the shear capacity. The total
contribution is given by the second term on the right-hand side of
Eqn (1.11) (or Eqn (1.12)). If this is less than 0.2
V
, increase the web
reinforcement to bring the total steel contribution up to at least 0.2
V
Step 5:
Check that the applied shear force
V
is less than the shear capacity
of the concrete section:
(1.13)
where λ
1
is as defined for Eqn. (1.11).
