F. K. Kong MA, MSc, PhD, CEng, FICE, FIStructE, R. H. Evans CBE, DSc, D ès Sc, DTech, PhD, CEng, FICE, FIMechE, FIStructE (auth.)-Reinforced and Prestressed Concrete-Springer US (1987)

Shear strength of deep beams 219
versities of Newcastle upon Tyne, Cambridge and Nottingham has led to
the following design method, which also covers deep beams with web
openings, [14-19].
The method is applicable where the span/depth ratio l/h does not
exceed about 3; however, as will become clear later, the shear-span/depth
ratio avfh (Fig. 6.5-1) is a more important parameter than the l/h ratio.
The method, which has since been included in Clause 3.4.2 of CIRIA's
Deep Beam Design Guide [12] and in Reynolds and Steedman's Reinlorced
Concrete Designer's Handbook [13] is based on the following formula for
the ultimate shear strength V [14-19, 27, 28]:
V = CI [1 - 0.35~] Itbh + C2 ± A * sin 2 a
= concrete resistance + steel resistance (6.5-1)
where CI = a coefficient equal to 1.4 for normal weight concrete and 1.0
for lightweight concrete;
C 2 = a coefficient equal to 130 N/mm 2 for plain round bars and 300
N/mm 2 for deformed bars;
It = the cylinder splitting tensile strength of the concrete; if It is
not available, it may be estimated from the cube strength leu
by, say, It = 0.4 to 0.5~/eu;
A = the area of a typical web bar-for the purpose of this
equation, the longitudinal tension bars are also considered to
be web bars;
y = the depth at which the typical bar intersects the critical
IT I
h 1 1 ,_,'
l "
Typical
web bar
" (area A)
,"'Main steel
i
-'---112
V
(a) Meanings of symbols
(b) Further symbols for
beam wlth openlngs.
Fig.6.5-1 Deep beam