Improvement of structures seismic response based on pendulum systems with double sliding surface

Abstract

The seismic isolation of the construction structures is of particular importance because the optimum stability premises of the structures during the seismic events are ensured. There are different isolation methods but based on the structure base isolation principle, the friction pendulum bearing systems (FPBS) have been used with good results in equipping new structures and also in rehabilitating of the old buildings that had to be consolidated. The double surface friction Pendulum (DSFP) bearing is an improved version of the well-known single concave friction pendulum bearing (FPBS). The principal benefit of the DSFP bearing is represented by its capacity to accommodate substantially larger displacements compared to a traditional FPBS of identical plan dimensions. Moreover, there is the capability to use sliding surfaces with different radius of curvature and friction coefficients, offering the designer greater flexibility to optimize the protective system performance. Through these systems good seismic isolation results are achieved for the building structures where mounted interposed between the foundation and the superstructure realizing the disconnection between the two structural elements. The disconnection is important because the insulated structure vibration period is modified in the sense of its significant increase, also with the increase of structure lateral flexibility, ultimately reducing the ground acceleration and avoiding the efforts vertical transmission to the isolated structure upper levels. The double surface friction pendulum system ensures an important modification of the isolated structure behavior materialized through the seismic response mitigation. This paper describes the double surface friction bearing (DSFP) constructive details with operation principles and also presents some numerical analysis results related to force–displacement relation considering different values of curvature radius and friction coefficients of the two friction surfaces used