Most of existing concrete structures do not have suitable seismic performance due to various reasons, therefore they need seismic rehabilitation. One of the seismic rehabilitation method in structural level is using of steel bracing. New investigation of steel bracing can be referred to eccentrically bracing with single vertical link. This method of rehabilitation provides many advantages such as increasing in ductility, stiffness, lateral resistance, architectural compatibility, low weight, and the fewest changes in primary structural system. In this paper, two existing 3-and 9-story RC frames are assessed on the basis of FEMA356. Eccentrically bracing with single vertical link is used for seismic rehabilitation of these frames. The results of nonlinear time history analysis based on the maximum inter-story drift, maximum roof displacement and plastic rotation in critical elements of original and rehabilitated frames for two performance levels of Life safety (LS) and Collapse Prevention (CP) are presented. The results indicate that single vertical link can lead structures to the desired performance level with minimum cost and braced span number.

Purpose The high heat induced by fire can substantially decrease the load-bearing capacity, which is more critical in unprotected steel structures than concrete reinforced structures. One of the conventional steel structures is a steel-plate shear wall (SPSW) in which thin infill steel plates are used to resist against the lateral loads. Due to the small thickness of infill plates, high heat seems to dramatically influence the lateral load-bearing capacity of this type of structures. Therefore, this study aims to provide an investigation into the performance of SPSW with reduced beam section at high temperature. Design/methodology/approach In the present paper, to examine the seismic performance of SPSW at high temperature, 48 single-span single-story steel frames equipped with steel plates with the thicknesses of 2.64 mm, 5 mm and 7 mm and yield stresses of 85 MPa, 165 MPa, 256 MPa and 300 MPa were numerically modeled. Furthermore, their behavioral indices, namely, strength, stiffness, ductility and hysteresis behavior, were studied at the temperatures of 20, 458, 642 and 917? The simulated models in the present paper are based on the experimental specimen presented by Vian and Bruneau (2004). Findings The obtained results revealed that the high heat harshly diminishes the seismic performance of SPSW so that the lateral strength is reduced even by 95% at substantially high temperatures. Therefore, SPSW starts losing its strength and stiffness at high temperature such that it completely loses its capacity of strength, stiffness and energy dissipation at the temperature of 917? Moreover, it was proved that by separating the percentage of their participations variations of the infill plate in SPSW, their behavior and the bare frame can be examined even at high temperatures. Originality/value To the best of the authors’ knowledge, the seismic performance of SPSW at different temperatures has not been evaluated and compared yet.