Sponsor: Internally Funded

PI: Oguzhan Bayrak
Co-PI: Trevor Hrynyk

The recent delamination failure of a concrete containment structure comprising a nuclear power production facility was attributed to low quality concrete and improper de-tensioning. Analytical results have shown that the delamination failure could not have been predicted due to a lack of knowledge regarding the behavior of curved post-tensioned concrete structures.

The objective of this research is to gain knowledge pertaining to the behavior of curved post-tensioned concrete structures under prestressing loads by (1) developing experimental data on curved post-tensioned concrete structures, (2) evaluating patterns of crack propagation due to localized tensile stresses, (3) investigating empirical relationships between the tensile strength of concrete and the delamination failure load of curved post-tensioned structures, (4) modifying the analysis procedure employed in an existing nonlinear reinforced concrete-dedicated finite element analysis program to account for the presence of radial stresses, and (5) developing practical design recommendations in an effort to prevent brittle delamination-controlled failure modes.

It is anticipated that this research will illustrate the significance of the size effect on delamination failures in curved post-tensioned structures and will establish a need for a minimum amount of radial (i.e., through-thickness) reinforcement to mitigate size effects and to prevent the occurrence of premature brittle failures. The enhanced 3D nonlinear analysis program developed through this research will serve as a practical method for assessing the performance of curved post-tensioned concrete structures and will be capable of capturing delamination failure mechanisms. Furthermore, it is anticipated that several practical requirements for the design of curved post-tensioned structures will be developed from this research: a minimum transverse reinforcement, a factor to account for an effective height to evaluate the maximum failure load, and a method to calculate radial (i.e., through-thickness) stress distributions.