Evaluation of PIRs Post-Fire Pull-Out Strength in Concrete Exposed to ISO 834-1 Fire
Résumé
Post-installed rebars (PIRs) using mortar can offer bond strength at ambient temperature
equal or higher to that of cast-in place rebars. However, high temperatures have the effect of
weakening the bond, typically governed by the chemical and physical properties of the mortar which
is often sensitive to temperature increase. Therefore, the behavior of PIRs in a fire situation becomes
vulnerable. Moreover, after exposure of PIRs to high temperature, the heat transfer continues during
the post-fire phase, which might endanger the construction after a fire event. In order to evaluate the
evolution of the pull-out capacity during fire, Pinoteau et al. have developed the bond resistance
integration method (Pinoteau’s RIM) to predict the bond resistance value of a rebar subjected to
various temperatures in accordance with the fire exposure curves. Therefore, accurate temperature
profiles during the post-fire phase are needed to ensure a correct calculation of the post-fire behavior
of the PIR connection. This paper presents 3D finite element thermal simulations of PIRs in concrete
exposed to ISO 834-1 fire conditions then cooled with ambient air. Numerical thermal profiles are
then compared to the experimental results (i.e., post-fire pull-out tests). The proposed model provides
guidelines for conducting numerical simulations to determine the thermal entry data necessary for
predicting thermal profiles in PIRs during heating and cooling phases. Then, the post-fire pull-out
capacity of PIRs in concrete is calculated using Pinoteau’s RIM, and compared to experimental
post-fire pull-out results.
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