Behavior of Prestressed Steel Beams

This paper reports on the behavior of simply supported (I-shaped cross section) steel beams prestressed by tendons. It is well known that this typology of beams has successfully been used mainly in the past. Prestressed steel beams are lighter than traditional ones that have the same length and vertical load capacity; this aspect could make them economically advantageous and a viable solution in many practical situations. This paper analyzes prestressed steel beams having a medium span ranging from 35 to 45 m and which are to be used as roof structural elements. This study focuses on two parameters that are considered two of the fundamental items for the design: the number of deviators and the value of the prestressing force. This study has been carried out with nonlinear finite-element analyses that take into account both mechanical and geometrical nonlinearities. In particular, the behavior of these beams has been investigated up to failure during tensioning and during loading (after tensioning). The effect on the structural response of bracing, which can be only at the top flange of the beams or at the top and bottom flanges of the beams, also has been considered.