Estudo preliminar à análise do colapso progressivo em edifícios de alvenaria estrutural sobre estrutura de transição em concreto armado

Abstract

One of the characteristics of structural masonry buildings is the difficult to make changes in the arrangement of apartment walls. If openings are made in structural walls, as a result of an inappropriate apartment layout modification, excessive displacements, large size cracking, local damage, even progressive collapse may occurs. However, there are few studies concerned with these situations, especially in the case of structural masonry buildings above concrete floors structures, emphasizing the importance of more accurate studies. The research presented herein aimed to evaluate the stresses redistribution on walls and the implications in others structural members, such as lintels and bond beams, as well as to evaluate the influence of concrete floor structure in this redistribution, suggesting a series of verifications to the study of progressive collapse in masonry buildings. For this purpose, two masonry buildings with different walls arrangement in plan were modeled using the equivalent frame model proposed by Nascimento Neto et. al. (2014). The analyzes were conducted to evaluate, at the nearest floors to the opening created by the removal of a structural wall portion, the normal and shear stresses at the walls base and at predetermined vertical cross sections; and normal forces in the bond beams. The results showed: the occurrence of intense stresses peaks in the floors immediately above and under the floor in which occurred the removal, which dissipates considerably two/three floors distant of the removal; the existence of masonry lintels, bond beams and walls interconnections are very important to ensure the occurrence of internal mechanisms to the stresses redistribution.