Cavilha de madeira reforçada com fibras de vidro como conector em seções mistas de madeira e concreto

Abstract

Considering the global trend to reduce the environmental impact caused by the construction industry, timber-based projects have increasingly emerged as an appropriate response to lowering the carbon footprint and embodied energy of building materials. This study proposes a connection system composed of hardwood dowels reinforced with glass fibers in an epoxy matrix (GFRP) as an alternative to metallic connectors in timber–concrete composite (TCC) structures. To achieve this objective, the research was divided into three stages: characterization of raw materials (timber, concrete, glass fibers, and GFRP), characterization of GFRP-reinforced dowels in terms of physical and mechanical properties (water absorption, bending strength, axial compression, embedment, and pull-out), and evaluation of connection systems in timber–concrete composite specimens through push-out tests. The push-out tests considered dowel diameter, reinforcement, and insertion angle into the timber as variables, resulting in eight experimental series. The results showed that GFRP reinforcement reduced the average water absorption rate by 85%, increased bending strength by 84%, and compression strength by 46%. Regarding pull-out, the behavior was limited by the low slenderness ratio, while embedment tests indicated that fiber orientation had no influence on strength, but affected post-failure behavior. Push-out tests confirmed the influence of orientation, diameter, and GFRP reinforcement on connection stiffness. For perpendicular dowels without reinforcement, increasing the diameter from 16 mm to 20 mm resulted in stiffness gains of 91% and 27% in the service slip modulus, respectively. With GFRP reinforcement, stiffness increased by approximately 35% to 104% in parallel and inclined series, respectively. When comparing orientations, inclined dowels exhibited up to 51% greater stiffness than perpendicular ones. Overall, the findings indicate that GFRP reinforcement enables composite action efficiencies comparable to those of metallic connectors, confirming its potential as a sustainable alternative for timber–concrete composite systems.