Reduction of structural response to near fault earthquakes by seismic isolation columns and variable friction dampers

Abstract

This paper focuses on the investigation of a hybrid seismic isolation system with passive variable friction dampers for protection of structures against near fault earthquakes. The seismic isolation can be implemented by replacing the conventional columns fi xed to the foundations by seismic isolating ones. These columns allow horizontal displacement between the superstructure and the foundations and decouple the building from the damaging earthquake motion. As a result, the forces in the structural elements decrease and damage that may be caused to the building by the earthquake signifi cantly decreases. However, this positive effect is achieved on account of displacements occurring in the isolating columns. These displacements become very large when the structure is subjected to a strong earthquake. In this case, impact may occur between the parts of the isolating column yielding their damage or collapse. In order to limit the displacements in the isolating columns, it is proposed to add variable friction dampers. A method for selecting the dampers' properties is proposed. It is carried out using an artifi cial ground motion record and optimal active control algorithm. Numerical simulation of a sevenstory structure shows that the proposed method allows effi cient reduction in structural response and limits the displacements at the seismic isolating columns.

Optimum design for more effective tuned mass damper system and its application to base-isolated buildings

“…Base‐isolation systems are very effective in reducing the seismic responses of buildings, while the base isolation itself undergoes a relatively large displacement. However, base‐isolated buildings as well as high‐rise flexible buildings are said to be vulnerable to long‐period ground motions, such as some famous earthquakes Landers (1992) and Chi‐Chi (1999), which are characterized by pulse‐type wave shape, abundant long‐period components, high ratio of peak ground velocity to peak ground acceleration, or sometimes large permanent ground displacement , due to resonant behaviors .…”

Composite periodic foundation and its application for seismic isolation

“…Ismail et al proposed an innovative isolation device, the roll‐n‐cage isolator, for aseismic design. Replacing the conventional columns by seismic isolation columns, Ribakov and his coworkers developed a hybrid seismic isolation system to protect structures against near‐fault earthquakes. Though effective, existing isolation systems typically suffer from several drawbacks.…”

Seismic performance of an innovative structural system having seesaw motion and columns equipped with friction dampers at base level

“…In the present paper, a similar study is introduced in which the friction has been used as the energy absorption source. Based on the available publications, most of the studies in which friction has been used as a source of energy dissipation, have considered the friction dampers in diagonal bracings (Pall and Pall, ; Altamira, ; Morales Ramirez, ), and only very few ones have discussed the use of friction dampers in columns (Azuhata et al ., ; Ribakov, ). Azuhata et al (2009) evaluated seismic performance improvement of an existing building designed based on the old Japanese Design Code, by inserting some devices with friction dampers in the middle part of the columns on the first floor; however, it should be noted that their study is limited to 2‐D analysis of the buildings.…”

“…Azuhata et al (2009) evaluated seismic performance improvement of an existing building designed based on the old Japanese Design Code, by inserting some devices with friction dampers in the middle part of the columns on the first floor; however, it should be noted that their study is limited to 2‐D analysis of the buildings. Moreover, Ribakov () used friction dampers as a part of isolating devices under the columns. The study, presented in this paper, considers the fully 3‐D behavior of buildings.…”