Note relative to the determination of «bending lengths» in double-sloping metal portal frames

Abstract

In the construction of industrial sheds, in contrast to the use of a rib isostatically braced on supports, there has been a constantly more frequent use of the doubles toping metal portal frame of small and medium spans. For the study of the lack of stability on the plane of the portal frame, recourse is had to the «bending lengths» method which makes possible a piece by piece check —a debatable procedure, but generally accepted on account of its operational nature. Although there are techniques of numerical analysis which made it possible to approach the problem of instability with precision, this note does not intend to introduce innovations in the treatment of the problem, but rather, accepting the approximate validity of the present method of calculation, proposes to provide rules of immediate application compatible with what is set out in Spanish standards.