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.jpg

sigma_spall_equation.jpg

alpha_e_equation.jpg

where:

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

P0      Initial prestressing force just after release in the considered web

bw      Thickness of the individual web

e0      Eccentricity of the prestressing steel

lpt1     Lower design value of the transmission length

k        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