Análise experimental de blocos de concreto reforçados com fibras de aço sobre uma estaca

Abstract

In this work, an experimental study was developed with the objective of evaluating the influ-ence of the addition of steel fibers in behavior in relation to the rigidity and the way of breaking of one pile caps. The experimental plan has consisted in the construction of 27 blocks divided into three groups. Two fiber rates corresponding to 50 kg / m³ and 60 kg / m³ (0.64% and 0.77% in volume, respectively) were adopted, being each rate characteristic of two distinct groups. The third group, which one there was no addition of fibers, was taken as reference for compar-ative analysis. For each group, 12 cylindrical specimens were molded to later characterize the used concrete by axial and diametrical compression tests. In addition, six metal plates of differ-ent sizes were used on the faces of the models to represent the section variation of the columns and piles. For each block of each group, the three metal plates for the columns (10 cm x 10 cm, 12,5 cm x 12,5 cm e 15 cm x 15 cm) were combined with the three metal plates for the piles (10 cm x 10 cm, 10 cm x 20 cm e 10 cm x 30 cm), thus totalizing nine possible combinations. The blocks were subjected to centralized load. The experimental results indicate the use of steel fibers increases the maximum load supported by the pile cap, influences the propagation of cracks favoring a less abrupt rupture mode, besides presenting a significant increase in tensile strength by diametrical compression. The stiffness of the pile caps is affected mainly by corre-sponding dimensions of the metal plates which simulated the piles. The variation of fiber rates also interferes with the stiffness of the pile caps when the section of the column and the section of the pile is fixed. The results point to the existence of a critical fiber volume, which one, if used, potentiates the strength abilities of the pile cap.