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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 2
Influence of steel fibers on the reinforcement bond of straight steel bars
the bonding strength is not important, since we only wish the bar to
reach its yield stress before being pulled out.
Table 4 shows the values for the basic anchorage length, determined
by the Brazilian and European standards for reinforced concrete struc-
tures, next to theAmerican Concrete Institute (ACI) code. The Brazilian
standard NBR 6118 [34] as well as the European standard Eurocode 2
[35] used Equation (4) to calculate the steel-concrete bonding strength.
(4)
ctd 321 bd
f
f

Here, f
bd
is the design value of the ultimate bond stress; η
1
is the coef-
ficient of superficial conformity of the bar (η
1
=2.25 for ribbed bars); η
2
is
a coefficient related to the quality of the bond condition and the position
Figure 6 – Load versus bar strain for test specimens with
bar of 10 mm diameter and anchorage equal to 10
Concrete without fibers
A
Concrete with 1% fibers
B
Figure 7 – Bar failure
CP10.10.2.A3
A
Detail of bar of CP10.10.2.A3
B
CP10.10.2.A4
C
1...,133,134,135,136,137,138,139,140,141,142 144,145,146,147,148,149,150,151,152,153,...190