Enhancing compressive strength of hollow masonry clay bricks by a novel use of internal and external GFRP wrappings

GFRP-based external strengthening of masonry walls is one of the most widely used retrofitting techniques. In contrast, GFRP internal reinforcement remains largely unexplored, despite its critical importance, duo to limited accessibility for post-construction assessment and repair. In this respect, the proposed paper investigates the behavior of innovative hollow masonry bricks internal and external glass fiber-reinforced polymer (GFRP) confinement using both experimental and analytical approaches. The novelty of the work consists of developing a new high-performance brick to be used as a unit in masonry walls. With the aim of enhancing axial behavior, the strengthened configuration was designed to combine an internal cross-shaped GFRP-sheet (longitudinally-oriented) with the protective and confining (laterally-oriented) role of the external strips. Accordingly, a set of above-mentioned GFRP strengthened clay brick was manufactured and tested under monotonic pure compression until failure. Based on the emphasized experimental results, an empirical analytical model was calibrated, and then compared with other available columns confinement models. The obtained outcomes in terms of axial capacity curves and failure modes, as well as the comparison of the approaches used, were provided. The main findings revealed that internal strengthening may increase the axial load capacity by approximately 70%, whereas the addition of external confinement resulted in a threefold improvement.