PBO mesh mobilization via different ways of anchoring PBO-FRCM reinforcements

This paper describes different ways of anchoring reinforcements made of PBO fibre mesh and improving their adhesion to concrete. Strengthening effectiveness and PBO-FRCM reinforcement mobilization were assessed on the basis of 12 models of strengthened RC beams. The beams were divided into two groups depending on the compressive strength of their concrete. Three ways of anchoring the PBO mesh were used in each of the groups. In type-A beams stirrups were made at the ends of the longitudinal reinforcement. In type-B beams the ends of the longitudinal reinforcement were wound on composite rods and bonded into transverse cuts at the ends of the beams. In type-C beams the longitudinal reinforcement was covered along its entire length with a layer of flexible mortar. The research to date shows that the improvement of the anchorage of the PBO mesh ends is of key importance for elements subjected to bending, shearing or compression. In this paper the behaviour of the beams under load is described on the basis of an analysis of their deflections. The distributions of strains in the longitudinal reinforcement depending on the beam type are shown. Attention is drawn to the redistribution of stress in the longitudinal reinforcement at the instant when the elements crack. The degrees to which the PBO mesh is mobilized depending on the way of anchoring the PBO-FRCM reinforcement were investigated.