Análise de painéis de contraventamento de edifício em alvenaria estrutural considerando os efeitos localizados de 2ª ordem

Abstract

The purpose of this study is to take into account the local second order effects on the design of masonry walls under vertical and lateral wind loads. In order to do that, a study case is presented comparing the design procedures stated on both the Brazilian standard of masonry structures of concrete blocks (NBR 15961-1:2011) and the British code of practice for the use of masonry (BS 5628-1:2005). Four large masonry panels of the ground floor of a 12 storeys building were selected to perform the calculations. These panels were divided into equal parts and analysed as individual columns, similarly to the procedure for the local analysis of shear walls given in the Brazilian Concrete Code (NBR 6118:2014). The dimensions and loading data of the panels have been taken from the structural design of the building, which was calculated using TQS (Brazilian software for structures design). The formulae given in the Brazilian standard for the calculation of masonry compressive strength consider the gross area of the section, whereas the British standard uses the net area. For this reason, in order to effectively compare the results, the require strength of the masonry walls, by means of the NBR’s procedure, was calculated using the net area of the section. Thus, the required masonry strength values obtained for each standard procedure were very close. However, the results of block and mortar resistances obtained were not as similar. The reason was due to the difference in the procedure of obtaining these values, which will be dealt with during this paper. The local second order effects were taken into account on the design. It was noticed that the required resistance increased significantly, meaning that it is important to consider these effects on the calculation. A design example was presented showing the calculations utilizing each standard procedure.