The minimum steel consumption in beams using the recommendations of the code NBR 6118-2003 - case study

Resumen

The Brazilian code NBR 6118:2003 prescribes the use of strut and tie models with variation of the strut angle () and tie angle () for the design of concrete beams submitted to bending and shear. This code permits the designer to choose between two models of design shear reinforcement: The model I were the strut angle has constant value of 45° and the nominal shear strength provided by concrete (Vc) has a constant value. In the model II the strut angle varies from 30° to 45° and the variation Vc is function of the design shear force (VSd) and the strut shear strength (VRd2) as well. The stirrups angle varies from 45° to 90°. With the objective of help the designers to choose the model and optimum angle, the proposed models were evaluated the order to lead to the minimum consumption of transverse and longitudinal steel in simply supported beams, subjected to combined shear and flexure, with distributed loading.