Effects of Inherent Structural Characteristics on Seismic Performances of Aseismically Base-Isolated Buildings
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TECHNICAL NOTE
Effects of Inherent Structural Characteristics on Seismic Performances of Aseismically Base‑Isolated Buildings Peyman Narjabadifam1 · Patrick L. Y. Tiong2 · Ramin Mousavi‑Alanjagh1 Received: 9 May 2018 / Accepted: 25 October 2019 © Shiraz University 2019
Abstract Effects of inherent characteristics of both isolation system (IS) and superstructure on seismic performances of aseismically base-isolated buildings subjected to near- and far-field ground motions are investigated through extensive numerical analyses. ISs considered are friction pendulum system (FPS) and high-damping laminated rubber bearing (HRB), as the most practical ISs. Superstructures are 3-, 7-, and 11-story buildings with steel and reinforced concrete moment-resisting and braced frames. Seven isolation strategies are practically designed by the ISs, using three target displacements and two coefficients of friction. Eighty-four structural models are created for the 12 superstructures isolated by the two ISs. 1176 nonlinear time history analyses are carried out on the two-dimensional models of the isolated buildings subjected to seven near-field and seven far-field ground motions. Base shears, story displacements, and story accelerations are studied as the performance criteria. It is shown that the effectiveness of aseismic base isolation depends significantly on inherent mass, stiffness, and damping of the structure. The effect of isolation damping is more than mass and stiffness of the superstructure. The effectiveness of aseismic base isolation with the design strategies controlled by target displacement increases by increase in the inherent mass and stiffness of the superstructure, while facing reduction due to inherent increase in the isolation damping. The effects are similar in near- and far-field ground motions. Seismic performances of FPS are less sensitive to the effects of inherent structural characteristics. With the conditions and parameters set in this study, it is found that FPS performs better than HRB, specifically in near-field excitations. Keywords Aseismic base isolation · Inherent structural characteristics · Ground motion · Sensitivity · Seismic performances
1 Introduction Aseismic isolation is a well-accepted effective method for protecting structures against earthquakes. It is generally used in the foundation level and is known as base isolation. This strategy of structural design is based on reducing the demand instead of increasing the capacity. Increasing the capacity can sometimes be uneconomical or impractical and may lead to situations in which the structure itself is undamaged but the contents are damaged or destroyed and the occupants injured. Aseismic base isolation reduces the seismic demand by * Peyman Narjabadifam [email protected] 1
Department of Civil Engineering, Faculty of Engineering, University of Bonab, Bonab 5551761167, Iran
Department of Research and Development, Base Isolation Technology (Asia), 41300 Klang, Selangor, Malaysia
2
reducing the fundamental frequency of th
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