Modelo de bielas e tirantes para blocos sobre duas estacas submetidos à carga excêntrica

Abstract

The study of foundations is one of the most complex stages in the design of a building, since it must attend the technical and economic conditions of structural and geotechnical engineering. Pile-caps design methods actually used were developed considering columns centralized to the cap. However, frequently designers came across eccentric loads that, due to its complex behavior and the lack of studies, became difficult to be solved. Thus, this work presents a study about stresses developed on caps over two piles, submitted to eccentric loading, aiming to contribute to the better understanding of the structural behavior of this element, and with the purpose of analyze and define strut-and-tie models. Nine pile-cap models were evaluated, varying: the position of the column in relation to the center of gravity of the pile-cap: centered, aligned to the pile or faced to the pile-cap; and its height: considering the inclination of the compression strut using angles of 45°, 50° and 55°. Numerical analyses were developed using ANSYS [trademark] software, assuming geometric and physical linear analysis, considering plane strain state, in order to identify the stress trajectory for each case and, based on these results, refined models of strutand- tie were defined using the software CAST [trademark]. From these models, equations were developed to verify the stresses in the compression struts and to determine the reinforcement area. It was verified that the variation of the position of the column influenced in the principal compressive stress of the pile-cap, increasing them as the increase of the eccentricity of the column, and that the height of the pile-cap is directly connected to the bearing capacity of the same, resulting in lower stresses inside the structure and reinforcement areas as the height increases.