Seismic Upgrading of Existing Rc Buildings by Slender Steel Shear Panels: A Full-Scale Experimental Investigation

Abstract

ABSTRACT:In the present paper the seismic upgrading of an existing RC structure by using slender steel shear panels is examined. Based on a preliminarily experimental evaluation of the performance of the bare RC structure, an ad hoc design procedure has been developed in the framework of the performance based design methodology. The applied device, whose configuration has been defined also according to both simplified and refined numerical analyses, is able to significantly enhance both the strength and the stiffness of the primary structure. It has been installed within a reaction steel frame, positioned into the bare RC structure, which is composed by members designed in order to remain in elastic regimen under the tension field action developed by plates. Since the original RC module was not able to withstand significant values of horizontal forces, the reinforcing of both the first level beam and the foundation beam by means of coupled channel steel profiles and threaded bars has been done. Finally, in order to assess the reliability of the proposed intervention, a full scale cyclic experimental test has been performed on the upgraded structure, confirming the effectiveness of the adopted technique as well as the validity of the proposed design procedure.Keywords: Slender steel shear panels, seismic upgrading, GLD building, experimental test, tension field mechanism, plate buckling INTRODUCTIONIn the framework of new seismic design approaches for upgrading existing reinforced concrete buildings, the development of innovative intervention techniques, based on either the reinforcement of existing structural elements or the introduction of new resisting systems, the metal-based technology approach can be considered very profitable [1]. Such a technique is founded on the energy dissipation capacity of special metallic devices able to achieve or improve the structural safety of the original structure under seismic actions.Within this category, the solution based on using metal shear panels can result particularly effective, due to the limited weight, the reduced volume obstruction, the easy insertion and the meaningful structural contribution offered by the applied devices in terms of strength, stiffness and ductility. In addition, it is important to observe that the self-weight of steel panels is rather low, if compared with the one of a reinforced concrete shear wall, determining in this way a reduction of gravitational loads and therefore of seismic actions transmitted to the foundation.Nowadays, metal shear panels adopted in seismic applications can be subdivided in two main behavioural classes: 1) the so-called "compact" panels, mainly made of low strength metallic materials (LYS steel or pure aluminium) and properly stiffened in order to avoid elastic shear buckling phenomena, which have been recently proposed for high steel buildings and also for reinforcement of RC buildings [2]; 2) the "slender" shear panels, made of thin steel plates, which have been widely studied and applied both in North America and ...

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