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 resistance in design ca/cu/ations (BS 8110) 211
are defined as shear links that will provide a shear resistance of
0.4 ~/mm2, i.e.
A ( . l' k) 0.4 b"sv
sv 0110. 10 S ~ 0.87fyv (6.4-2)
where A sv is the area of the two legs of a link, fyv the characteristic
strength of the link (not to be taken as more than 460 ~/mm2) and
Sv the link spacing.
~ote the following link spacing requirements:
(1) In the direction of the span, the link spacing Sv should not exceed
0.75d.
(2) At right angles to the span, the horizontal spacing should be such
that no longitudinal tension bar is more than 150 mm from a
vertical leg of a link; this spacing should in any case not exceed d.
Step 4 0.5 Ve :S V :S (Ve + 0.4)
It V is between 0.5ve and (ve + 0.4), provide minimumlinks as defined by
eqn (6.4-2) for the whole length of the beam.
Step 5 (ve + 0.4) < V
It V exceeds Ve + 0.4, provide links as follows:
A > (v - ve) b"sv
sv -- 0.87fyv
(6.4-3)
where the symbols have the same meanings as in eqn (6.4-2). The link
spacing requirements listed under eqn (6.4-2) apply equally to eqn
(6.4-3) here.
For the use of bent-up bars see 'Comments on Step 5' at the end.
Step 6 Anchorage of links
BS 8110: Clause 3.12.8.6 lists the following requirements on the
anchorage of links:
(a)
A link should pass round another bar of at least its own size,
through an angle of 90°, and continue for a length of at least eight
times its own size; or
(b) It should pass round another bar of at least its own size, through an
angle of 180°, and continue for a length of at least four times its
own size.
Comments on Step 1
See eqn (6.2-1).
Comments on Step 2
BS 8110's limits of 0.8y'feu and 5 N/mm2 are essentially the values
assigned to the ultimate shear stress V u of eqn (6.3-11), discussed earlier in
Section 6.3. The limits 0.8y'feu and 5 ~/mm2 already include an allowance
for the partial safety factor Yrn of 1.25.
Comments on Step 3
(a) Longitudinal bars are customarily curtailed when they cease to be
required to resist bending moment. It has been pointed out that such
curtailment creates stress complications which may substantially