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# Deformation of non-fully cracked members which are subjected mainly to flexure, α

## 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"); } }; });  7.4.3 (3)

The deformation may be estimated as follows:

 α = ζ αII + (1 - ζ) αI (7.18)

where:

α
is the deformation parameter considered which may be, for example, a strain, a curvature, a rotation, (or a deflection as a simplification, see the calculation of shrinkage curvatures).
αI, αII
are the values of the parameter calculated for the uncracked and fully cracked conditions respectively
ζ
is a distribution coefficient (allowing for tensioning stiffening at a section) given by:
 ζ = 1 - β (σsr/σs)2 (7.19)

with:

ζ = 0 for uncreacked sections
β
σs
the stress in the tension reinforcement calculated on the basis of a cracked section
σsr
the stress in the tension reinforcement calculated on the basis of a cracked section under the loading conditions causing first cracking
Note:
σsr/σs may be replaced by Mcr/M for flexure or Ncr/N for pure tension, where Mcr is the cracking moment and Ncr is the cracking force.

This application calculates the deformation α from your inputs.

Input
MPa
MPa

Output
ζ
(7.19)
the deformation α
(7.18)