A Displacement-Based Design Approach for Seismic Retrofitting of RC FRames with Steel Braces

The introduction in Europe of the new regulation for seismic design will impose stricter performance requirements for building structures. This will result in a significant number of existing reinforced concrete structures having inadequate seismic resistance and therefore requiring intervention. One of the possible retrofitting options is the application of steel braces. However, this approach is not widely used due to the lack of seismic regulation in this field. The main goal of this work is the development of a fast and reliable design method that can promote the retrofitting of reinforced concrete frames with steel braces. In the last years, the scientific community has demonstrated that seismic design based in displacements is more adequate and rigorous that the traditional based in forces. Focused in obtaining the fundamental parameters for the application of this new method, it has been realized static and dynamic non-linear analysis in reinforced concrete structures strengthened with concentric steel braces. The results enable the definition of parameters such as displacement profiles, yielding displacements and target displacements among others. Based on the obtained results, it is proposed a displacement based method that enable, in a simple way, to design the retrofitting system so that the hybrid structure presents adequate seismic behaviour.N/