Civil Engineering Reference
In-Depth Information
Apex zone
α
ap
α
ap
0.5
h
ap
0.5
h
ap
(a)
h
=
h
ap
(1)
α
a
α
= 0
α
ap
+ 0.5
h
ap
r
=
r
in
r
in
r
in
r
in
(b)
h
ap
α
ap
α
ap
r
in
r
in
(c)
NOTE: In curved and pitched cambered beams the apex zone extends over the curved parts of the beam.
Figure 19.13 (a) Double tapered beam; (b) curved beam; (c) pitched cambered beam (BSI, in press). Permission to reproduce extracts from BS EN
14080 is granted by BSI
Note that the tensile stress perpendicular to the grain may
require radial reinforcement usually in the form of bolts, glued
in rods or screws.
(d)
For combined tension perpendicular to the grain and shear
in the apex zone
Glulam, with a profi le similar to the pitched cambered beam,
is often used for three pinned arch construction. Under gravita-
tional loading the stress perpendicular to the grain in the 'apex'
zone is then compression which may reverse to tension under
wind loads. The principal practical problem is transporting the
half span member from the factory to the site. Note that the
decision to use [6.54] is UK NA 2.4.
σ
τ
t,90,d
σ
t,90,d
σ
ττ
[6.53]
11
10
+
t,90,d
≤
f
k
k
f
t,90,d
f
t,90,d
v,d
dis
vol
t,90,d
v,d
