Experimental and numerical study of the behaviour of high dissipation metallic devices for the strengthening of existing structures

Abstract

The use of steel bracing systems for the strengthening of existing reinforced concrete (RC) frames may lead to increase of both strength and stiffness. However, in most of the cases the main target is the increase of the energy dissipation capacity. This paper studies, both experimentally and numerically, the efficiency of a specific strengthening type which utilizes a small steel link element having an I-shaped cross-section connected to the RC frame through bracing elements. The energy is dissipated through the plastification of the steel link element. The case studied in this paper is a typical one bay, single storey RC frame constructed according to older code provisions, which is strengthened through two different types of steel link elements. The behaviour of the strengthened frames is studied with respect to the one of the original bare frame. The experimental study is supported by complete numerical simulations of the performed tests. To this end, detailed numerical models are formulated, which are able to follow the highly non-linear nature of the problem, involving the plastification of the steel rebars, the cracking and plastification of concrete and the plastic deformation and hysteretic response of the dissipative link elements.