Avaliação de modelos de dimensionamento para sapatas isoladas rígidas

Abstract

This work aims to evaluate the influence of different design methods on rigid spread footings. Three distinct structural design methodologies were compared: the Strut-and-Tie Model (STM) based on force equilibrium, the STM based on moment equilibrium, and the traditional flexural theory. The analysis was conducted through a real case study, using the plan of a building with multiple columns subjected to different loading conditions. Three representative columns were selected for the comparative study, and both geometric and structural designs were carried out according to each method. The adopted methodology involved calculating the maximum stresses at the footing base, verifying the compressed strut, and determining the required reinforcement areas for each model. The results indicated that the choice of design method significantly impacts material consumption and, consequently, foundation costs. It was also verified that footings designed with equal cantilevers resulted in more economical designs compared to those with unequal cantilevers. The STM based on force equilibrium generally required less reinforcement, while the STM based on moment equilibrium resulted in larger steel areas. The flexural theory model presented reinforcement areas similar to those of the force equilibrium method, with more simplified procedures that are commonly adopted in practice. The study also revealed that footing stiffness and load eccentricity directly influence stress distribution, affecting the selection of the most efficient model. It is concluded that for the analyzed situations, the STM based on moment equilibrium is recommended, as well as geometric design with equal cantilevers, highlighting the importance of evaluating foundation stiffness and acting loads when choosing the most appropriate design model.