A Study of Loading Capacity Increase in Modified Ductile Ring Fuse in Concentric Braces

ABSTRACT: Concentric braced frames are kinds of structural systems which are used more than other systems in multi-storey buildings. This is due to the ease of their construction and their capability of economizing the projects. Concentric braces contain sufficient lateral stiffness but they don’t have adequate ductility. Various methods have been suggested to increase the ductility of these braces by researchers. One of these methods is to dissipate the energy by using a ring which is installed at the end of the brace members. Researches indicate that performance of this element result in ductility increment in concentric braces. However loading capacity of the ring element is limited and its ductility decreases by increment of its diameter and it may also limit some architectural aspects in the braced span. In this article the possibility of increasing the loading capacity of the ring by adding ductile steel plates has been studied, so that the new element acts as a fuse for different ranges of loads and prevents other members of the structure to enter the non-linear phase. The stresses and deflections have been studied by using a non-linear finite elements analysis under cyclic loadings. Resulted hysteretic curves indicate that added plates have effectively increased the ring’s loading capacity whilst providing desirable ductility.