Análise do comportamento estrutural e durabilidade de pilares de concreto armado reforçados com manta de GFRP

Abstract

Fiber reinforced polymers (FRP) are an attractive option for the strengthening of structures in the civil construction due to the intrinsic characteristics of the system, e.g., lower self-weight, ease and versatility of application and little change of cross section of the strengthened element. The Externally Bonded Reinforcement (EBR) technique consists on the use of fibers sheets, impregnated with polymeric matrix glued to the substrate of the element that will be strengthened. However, structures strengthened by the EBR technique exposes the FRP to direct contact with different degrees of environmental aggressiveness (weathering, humidity, temperature and ultraviolet radiation) and to possible accidents (fires, explosions, floods, physical shocks and acts of vandalism). These factors can cause degradation of the constituent materials of the strengthening system changing their rupture modes and leading to reductions of the ultimate stress. In order to evaluate the structural behavior and durability of reinforced concrete columns confined with Glass Fiber Reinforced Polymer (GFRP) by the EBR technique when exposed to weathering in a subtropical climate region (Cwa in Köppen–Geiger climate classification system), short columns were evaluated by compression axial tests. In addition, epoxy resins and GFRP were evaluated by uniaxial tensile tests. The results indicate decreases in the mechanical properties of the epoxy resins, while no degradation was obtained for the GFRP composites. Concerning to the short columns, decreases of the ultimate stresses and axial strains were observed after weathering exposure. However, the exposure did not decrease the efficiency of the strengthening system when compared to the unstrengthened column.