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Serviceability limit state - Eurocodes

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Stresses in reinforcement for final crack<br />

formation<br />

G. Hanswille<br />

Univ.-Prof. Dr.-Ing.<br />

Institute for Steel and<br />

Composite Structures<br />

University of Wuppertal-Germany<br />

Δσ p2<br />

σ s2<br />

Δσ p2<br />

Δσ p1<br />

σ s1<br />

σ s<br />

A s , d s<br />

A p , d p<br />

σ c<br />

σ c =f ct,eff<br />

x<br />

Equilibrium at the crack:<br />

N − P<br />

Maximum crack spacing:<br />

f<br />

s<br />

ct<br />

δ<br />

s<br />

A<br />

r,max<br />

σ<br />

c<br />

s2<br />

o<br />

= δ<br />

s<br />

=<br />

d<br />

=<br />

2τ<br />

− σ<br />

=σ<br />

p<br />

r,max<br />

=<br />

2<br />

s1<br />

s2<br />

sm<br />

σ<br />

s<br />

s<br />

=<br />

s2<br />

A<br />

[ τ n d π + τ n d π ]<br />

f<br />

(A<br />

sm<br />

ct,eff<br />

s<br />

r,max<br />

s<br />

A<br />

+ ξ<br />

c<br />

2<br />

U<br />

A<br />

− β( σs2<br />

− σs1)<br />

Δσp,2<br />

− β(<br />

Δσp2<br />

− Δσ<br />

=<br />

E<br />

E<br />

s<br />

s<br />

A<br />

Compatibility at the crack:<br />

s<br />

2<br />

+ Δ σ<br />

s<br />

s<br />

p2<br />

p<br />

τ<br />

)<br />

sm<br />

pm<br />

Equilibrium in longitudinal direction:<br />

A<br />

p<br />

σ<br />

p2<br />

p<br />

p<br />

− σ<br />

p1<br />

s<br />

=<br />

r,max<br />

2<br />

p<br />

U<br />

A<br />

p<br />

p<br />

τ<br />

pm<br />

p1<br />

)<br />

s r,max<br />

mean crack spacing: s r,m ≈2/3 s r,max<br />

39

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