Avaliação da influência de esforços normais no banzo no comportamento estrutural de ligações tubulares em aço.

Abstract

The second half of the twentieth century was associated to widespread use of structural hollow sections in Brazil following a worldwide trend observed in countries like Germany, England, Canada, Japan and the United States In addition new technologies have been allowing the development of high resistance tubes with yield stress around 1,000 MPa made with materials such as stainless steel and made possible the use of alternative cross-shaped hollow sections such as triangular and elliptical. All these aspects urged for an improvement of the procedures associates to structural design and analysis that could lead to a rational, safe and economical use, of these materials. This work aims to experimentally investigate T joints formed by RHS and SHS structural sections and compare their response with the recommendations contained in NBR 16239 [3], EC3-1.8 [4] and ISO 14346 [5] design standards. Seven specimens were tested made of RHS 100x80x6,3mm and SHS 60x60x6,3mm subjected to compressive load in the brace and varying the level of normal force on the chord. The tests results enable a comprehensive analysis of the structural performance were the ultimate capacity of the T joints could be evaluated and compared to the usual deformation limit criteria and to the theoretical results present in current design standards. One of the main conclusions of the present study, for the investigated T joints geometries, was that the NBR 16239 [3] and EC3-1.8 [4] forecasted ultimate load values were compatible to the results obtained in the experiments for cases without chords forces and for compressive chords forces up to 70% of the plastic cross section capacity. Alternatively, in these cases the ISO 14346 [5] led to conservative predictions. The tests with tension chords axial forces also led to conservative predictions for the three investigated design standards.