Resistance to spalling (hollowcore)

The control is carried out for the first load combination in SLS for each chain of dependence, usually those marked "Release." Formulas to consider are those from EN1168 4.3.3.2.1.

 

The general control states that the spalling stress (σsp) must not exceed the spalling capacity (fct).

 

sigmasp_noexceed_fct
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sigma_spall_equation
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alpha_e_equation
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where

 

fct        is the value of the tensile strength of the concrete from the current load combination (see above)

P0        is the initial prestressing force just after release in the considered web

bw        is the thickness of the individual web

e0        is the eccentricity of the prestressing steel

lpt1        is the lower design value of the transmission length

k        is the core radius equal to the ratio of the section modulus of the bottom fibre and the net area of the cross section (Wb/Ac)

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PRE-Stress Documentation