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)

222 Shear, bond and torsion
(c)
The f3 values in Table 6.6-1 already include a partial safety factor Ym
of 1.4 (see Table 1.5-2).
The anchorage bond length 1 (of ten simply called the anchorage length) is
the length of the reinforcement bar required to develop the stress fs and is
given by eqns (6.6-1(b» and (6.6-2):
1 = fs 4J (6.6-3(a»
4f3~feu
The ultimate anchorage bond length lu (of ten referred to as the ultimate
anchorage length or the full anchorage length) is the bar length required to
develop the full design strength. Hence, by writing fs = O.87fy in eqn
(6.6-3(a)),
1 = O.87fy4J (6.6-3(b»
u 4f3Heu
where 4J is the bar size and fJ is as defined in eqn (6.6-2). Typically, for
feu = 40 N/mm 2 and fy = 460 N/mm 2 (deformed bars) , the ultimate
anchorage bond length is 324J for bars in tension and 264J for bars in
compression (see also Table 4.10-2).
Where it is impracticable to provide the necessary anchorage length for
bars in tension, the designer may use hooks or bends (Fig. 6.6-1), which
should meet the detailing requirements of BS 4466, summarized here in
Fig. A2-1. The equivalent or effective anchorage length of such a standard
hook or bend may then be taken as multiples of the bar size 4J shown in
Table 6.6-2, adapted from the I.Struct.E. Manual (26).
For anchorage of links, see Section 6.4, Step 6.
Example 6.6-1
Referring to the beam in Example 6.4-2 (Fig. 6.4-1), check the tension
and compression anchorage lengths required at support B.
SOLUTION
Where it is known that the bars are stressed to approximately their full
design strengths, the anchorage lengths are calculated immediately from
(a) Hook
(b) Bend
Fig. 6.6-1 Hooks and bends (r <: 2t/J for mild steel bars; r <: 3q, for high yield ban
up to size 20 rnrn and <:44> or larger sizes)