Civil Engineering Reference
In-Depth Information
1
Reinforced concrete deep beams
F.K.KONG and M.CHEMROUK, University of
Newcastle upon Tyne
Notation
V
shear force
A
h
area of horizontal web reinforce-
ment with a spacing sh
V
c
shear strength provided by con-
crete
A
r
area of reinforcement bar
v
c
shear stress value
A
s
area of main longitudinal rein-
forcement
V
n
nominal shear strength
V
s
shear strength provided by steel
A
v
area of vertical web reinforce-
ment within a spacing
s
v
V
u
design ultimate shear force;
shear capacity
b
beam thickness
v
u
c
,
c
1
,
c
2
support lengths
ultimate shear stress value
v
x,
v
ms,
d
effective depth
shear stress parameters
v
wh,
v
wv
x
f'
c
concrete cylinder compressive
strength
clear shear span; shear span
x
e
effective clear shear span
f
cu
(
f
y
)
characteristic strength of con-
crete (of reinforcement)
y
r
distances defined in Eqn (1.11)
z
lever arm
h
overall height of beam
g
m
partial safety factor for material
(typically,
g
m
=1.15 for reinfor-
cement and 1.5 for concrete)
h
a
effective height of beam
l
effective span
l
o
clear distance between faces of
supports
θ
angle
θ
r
angle defined in Eqn (1.11) and
M
moment
M
u
design ultimate moment; mo-
ment capacity
l
coefficient
l
1
coefficient
s
h
spacing of horizontal web rein-
forcement
l
2
coefficient
r
steel ratio
A
s
/bd
s
v
spacing of vertical web reinfor-
cement
f
capacity reduction factor; angle
1.1
Introduction
Recent lectures delivered at Ove Arup and Partners, London (Kong, 1986a),
and at the Institution of Structural Engineers' Northern Counties Branch in
Newcastle upon Tyne (Kong, 1985), have shown that reinforced concrete
deep beams is a subject of considerable interest in structural engineering
practice. A deep beam is a beam having a depth comparable to the span
length. Reinforced concrete deep beams have useful applications in tall
buildings, offshore structures, and foundations. However, their design is not
yet covered by BS 8110, which explicitly states that 'for the design of deep
beams, reference should be made to specialist literature'. Similarly, the draft
Eurocode EC/2 states that 'it does not apply however to deep beams…' and
