International Institute of Earthquake Engineering and Seismology Journal of Seismology and Earthquake Engineering 1735-1669 27 1 2025 01 01 Collapse Mechanism Investigation of Mass-Isolated Systems 73 87 715254 10.48303/jsee.2024.2038378.1119 EN Saeid Saharkhizan Ph.D. Candidate, Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran 0009-0000-6929-4842 Mansour Ziyaeifar Associate Professor, Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran Journal Article 2024 08 14 Rare earthquakes cause heavy damages to building structures. Design of structures using yield mechanisms that provide extra resources to ensure structural stability for intensity higher than the design-based earthquake (DBE), can be considered as a reasonable technique to reduce the collapse probability. In this regard, the design of a mass-isolated structural system with a multi-phase seismic behavior as a reliable lateral load-bearing system has been investigated. In this type of configuration, by separating the mass from the stiffness of the system in the vertical direction, the structural system is transformed into two subsystems (soft and stiff), which can be utilized as an<br>effective damping amplification technique by using an appropriate energy dissipation mechanism between these two parts. Furthermore, it can be used as an efficient seismic rehabilitation method for non-code-confirmed structures. In this study, in addition to performing parametric studies to determine the optimal damping coefficient, the impact and ultimate collapse mechanism of the system have been simulated and investigated numerically. The results of nonlinear time history analysis indicate that the mass-isolation technique can efficaciously improve the seismic performance of buildings compared to conventional structural systems due to the multi-phase seismic<br>behavior. Mass-isolation multi-phase behavior damping amplification Impact Collapse Probability https://www.jsee.ir/article_715254_24b0cd4c12a71d434f3a65b0b30dbbf0.pdf