Análise experimental de blocos sobre duas estacas metálicas com armadura metálica e não-metálica de barras de polímeros reforçada com fibra de vidro (GFRP)

Abstract

Pile caps are fundamental structural elements in deep foundation systems, responsible for transferring loads from the superstructure to the piles. Due to their typical exposure to aggressive environments, such as high moisture conditions, these elements are prone to deterioration associated with steel reinforcement corrosion, which motivates the investigation of more durable reinforcement alternatives. In this context, this study experimentally evaluated the structural behavior of rigid pile caps supported by two steel piles, designed according to the strut-and-tie method, comparing models reinforced with CA-50 steel bars and glass fiber-reinforced polymer (GFRP) bars. All models were designed with identical geometry, loading conditions, and concrete strength, varying only the type and distribution of the main tensile reinforcement. The experimental program included material characterization tests, load tests up to failure, and detailed instrumentation to monitor strains, displacements, crack development, and load distribution at the supports. The results showed that steel-reinforced pile caps exhibited behavior consistent with rigid block assumptions, presenting lower deformations and better crack control. Conversely, GFRP-reinforced pile caps showed larger deformations and crack widths, indicating a more flexible structural response, even when designed using the same criteria. It was also observed that distributing the GFRP reinforcement along the entire length of the tie resulted in improved structural performance compared to concentrating the reinforcement only in the anchorage region. The study concludes that the use of GFRP bars in pile caps is structurally feasible in terms of ultimate strength; however, additional design criteria related to deformation and crack control are required.