Author(s)

O. Sircovich Saar

Abstract

This paper relates to hardening systems, their response to dynamic forces and their contribution to seismic isolation of buildings’ foundations. The free vibration curve for a structure of continuous gradual changing of period and frequency, the dynamic load factor (DLF) for a suddenly applied constant load, and the curve of resonance for a pulsating sinusoidal force, are analyzed from the perspective of a structural engineer, which is essentially different from that of a researcher. The paper suggests a new approach for base seismic isolation, which is a combination of a base isolation device and a hardening steel structure. While the contribution of the isolation device is its characteristically high flexibility, the contribution of the steel structure consists of a smooth reduction of the building’s base displacement under a given earthquake. The combined isolation system also provides a gradual limitation of the building’s base displacement under an unexpected increase of the earthquake’s peak ground acceleration (PGA). Keywords: seismic isolation device, hardening steel structure, smooth reduction of base displacement, limitation of base displacement. 1 Introduction This paper presents a new approach for base seismic isolation, which is a combination of a base isolation device and a hardening steel structure. According to the results of preliminary investigations, this combination is conducive to a remarkable reduction of the maximum displacement of the isolated structure and to an appreciable limitation of this displacement under and unexpected increase of the design earthquake’s PGA. The response of a linear elastic structure, (curve 1 in fig. 1), subjected to a dynamic load is very well known and its basic characteristics, such as natural

Keywords

seismic isolation device, hardening steel structure, smooth reduction of base displacement, limitation of base displacement.