Estudo teórico e experimental de paredes esbeltas de alvenaria estrutural

Abstract

The resistance to compression is the property that determines the use of masonry as a structural system since the great majority of structural elements in such systems are generally subjected to compressive stresses. One of the factors to be taken into account in the design of these compression elements is their slenderness. For design in Brazil it is still used the concept of simplified slenderness where the buckling length is determined by an effective depth (hef) and the radius of gyration is replaced by a parameter called the effective thickness (tef) for calculating a resistance reduction factor. This reduction factor has its origin in very old international standards and building codes, dating back to when these codes used the allowable stresses method for the dimensioning of structural elements; due to its age, an effective explanation and derivation of this factor, therefore, has been lost and is unknown at this time. With the various updates of international standards for structural masonry and the consequent adoption of the limit state design method for dimensioning of elements, this factor has been abolished. In the Brazilian standards, however, even with the adoption of the limit state design method, this factor is still used, which is a contradiction. Studies on the strength reduction due to slenderness effects show that there are large differences when comparing the results given by the simplified method in the NBR with those given by international standards. These differences probably don t lead to loss of structural integrity of structures in Brazil because the slenderness ratio has been limited to low values, particularly in the case of unreinforced masonry.