RESUMO: Esta pesquisa avaliou a influência da substituição de agregados graúdos naturais (AGN) por agregados reciclados de concreto (ARC) na resistência ao cisalhamento de vigas de concreto armado. Ensaios experimentais em seis vigas de concreto armado com taxas de substituição de ARC de 0%, 30% e 100% são apresentados. Além disso, um banco de dados com resultados de 170 ensaios em vigas com ARC é utilizado para discutir os ajustes nas recomendações apresentadas pela ABNT NBR 6118 para estimar a resistência ao cisalhamento de vigas de concreto armado. Segundo o Demerit Points Classification (DPC), proposto por Collins, 80% dos resultados teóricos obtidos com os modelos I e II da norma brasileira caem dentro de uma faixa considerada de segurança apropriada, mostrando que a substituição dos AGN por ARC tem baixa influência na resistência ao cisalhamento de vigas de concreto armado.

ABSTRACT: This research evaluates the influence of the replacement of natural coarse aggregates (NCA) by recycled concrete aggregates (RCA) on the shear strength of reinforced concrete beams. Experimental tests on six reinforced concrete beams with RCA replacement ratios of 0%, 30%, and 100% are presented. Furthermore, a database with results of 170 tests on beams with RCA is used to discuss adjustments in the recommendations presented by ABNT NBR 6118 to estimate the shear strength of reinforced concrete beams. According to the Demerit Points Classification (DPC) proposed by Collins, 80% of the theoretical results obtained using models I and II from the Brazilian code fall in an appropriate safety condition range, showing that the substitution of NCA by RCA has a low impact on the shear strength reinforced concrete beams.

Abstract D-regions are defined by its non-linear strain distribution over a cross section. Deep beams are an example of D-regions, as most of its load is usually directly delivered to supports by arch mechanism. The present paper focus on the Stringer-Panel Method (SPM), an alternative procedure to some well-known methods for designing this type of structure, i.e., strut-and-tie method and finite element method. A manual approach of SPM is presented, by means of a simple principle of dividing a structure on two distinct elements: stringers, which absorb normal forces, and panels, which absorb shear forces by membrane action. Two practical examples of deep beams designed using SPM are presented and their overall behavior were investigated by means of non-linear analysis. Obtained results have shown that SPM is a very attractive alternative for analyzing reinforced concrete deep beams.