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# Anchorage of longitudinal reinforcement: the ultimate bond stress fbd

## Eurocode 2 part 1-1: Design of concrete structures \$(document).ready(function () { var freeExample = \$("#freeExample").length; \$("#mainMenu li#nav-appCate, #mainMenu li#nav-appEC211").addClass("active"); var proUser = false === true || false === true || freeExample !== 0; if (!proUser) { \$('#Input input').keyup(function(){ \$('#AlertSubscribe').modal(); }); \$('#Input select').change(function(){ \$('#AlertSubscribe').modal(); }); }; var tempInput = \$("#tempInput").text(); if (tempInput != "") { \$("#Input").parent("form").deserialize(tempInput); if (proUser) { \$("#acceptBtn").trigger("click"); } }; });  8.4.2 (2)

The design value of the ultimate bond stress for ribbed bars may be calculated as:

 fbd = 2,25 η1 η2 fctd (8.2)

where:

fctd
is the design value of concrete tensile strength
 fctd = αct fctk,0,05 / γC (3.16)

with

fctk,0,05
the characteristic (5% fractile) axial tensile strength of concrete, see Table 3.1
γC
the partial safety factor for concrete, see § 2.4.2.4 (1), § 2.4.2.4 (2), and § 2.4.2.4 (3)
αct
a Nationally Determined Parameter, see § 3.1.6 (2)P.
η1
is related to the quality of the bond condition and the position of the bar during concreting (cf. Figure 8.2):
η1 = 1,0 for "good" conditions,
η1 = 0,7 for other cases.
η2
is related to the bar diameter:
η2 = 1,0 for Φ ≤ 32 mm,
η2 = (132 - Φ)/100 for Φ > 32 mm.

This application calculates the ultimate bond stress fbd from your inputs. Intermediate results will also be given.

Input
mm
MPa

Output
η2
fctd
MPa (3.16)
the ultimate bond stress fbd
MPa (8.2)