Beams designed to shear by calculation models I and II of NBR 6118:2014

Abstract

In the present paper, a study on the design of reinforcements to resist shear efforts in reinforced concrete beams was developed. In the literature review, the main topics related to stirrups dimensioning were addressed according to calculation models I and II of NBR 6118:2014. From the bibliographic review, and using Microsoft Excel, an electronic spreadsheet was developed to calculate shear reinforcement areas for rectangular section concrete beams. Then, a case study was conducted in which were designed transversal reinforcements for 15 beams, according to calculation models I and II. The beams were organized in three sets, covering the most recurrent design widths (15, 20 and 25 cm), and in each set, the heights were chosen among the five most recurring design measures (20, 30, 40, 50 and 60 cm). In the case study, it was obtained for each beam the maximum and minimum shear reinforcement area according to the calculation models I and II, and other NBR 6118: 2014 requirements. In this research it was concluded that, for the set of beams analyzed, the calculation model II, for concrete strut with a 30º, has a greater saving area in relation to model I, however, with percentages varying according to each studied case.