Effect of the elevatd temperatures on the structural response of PBO-FRCM systems and PBO-FRCM strengthened reinforced concrete beams

The paper reports the results of an experimental investigation on the effect of elevated temperature exposure on the mechanical response of concrete members strengthened with PBO-FRCM composites. Fourteen direct shear (DS) tests on PBO-FRCM prisms and four flexural tests on RC beams either un-strengthened or PBO FRCM strengthened were performed over a temperature range from 20°C to 300 °C. Afgter being exposed to elevated temperatures, specimens were cooled naturally to room temperature and tested until failure. The obtained results confirm that the effect of the temperature on the FRCM-to-concrete bond behavior is a matter of concern for building applications: at 300 °C, the retained bond strength was almost -60% of the ambient temperature vakues. On the other hand, the flexural behavior of the FRCM strengthened RC beams seems to the much less affected by elevated temperature: in fact, the ultimate loads demonstrated negligible reductions for the tested range of tempertaure.