10 papers analyzed
These studies suggest that various seismic isolation systems, including partial mass isolation, base isolation, and multi-level isolation, effectively control seismic vibrations, reduce displacements and accelerations, and improve the seismic performance of buildings.
Seismic isolation is a critical technology in enhancing the earthquake resilience of buildings. This review synthesizes findings from multiple studies to evaluate the efficiency of various seismic isolation systems in buildings with different structural configurations.
Partial mass isolation (PMI) systems have been shown to be effective in controlling seismic vibrations by isolating different portions of story masses. Studies indicate that PMI configurations with isolated mass ratios (IMRs) between 0.25 and 0.50 can efficiently mitigate overall building seismic responses and control isolated components' responses. This system can be optimized to achieve near-optimal solutions by using identical isolated components at different stories, particularly in the upper stories, which simplifies construction and design.
Research on fully base-isolated (FBI) adjacent buildings with segregated foundations highlights the significant improvement in seismic responses compared to fixed-base buildings. The base isolation system effectively reduces displacement, although its impact on acceleration is less pronounced. The study also emphasizes the importance of considering separation distances between adjacent buildings to optimize the performance of base isolators.
The seismic response of base-isolated structures during impact with adjacent structures has been investigated, revealing that while base isolation remains effective, the superstructure acceleration increases and bearing displacement decreases upon impact. The study suggests that the effects of impact are more severe for systems with flexible superstructures and increased story numbers, necessitating careful design to avoid such impacts.
Introducing seismic isolation at various elevations within multi-storey structures can further enhance earthquake resilience. This approach helps in controlling partial and overall stiffness, force transmission, and energy dissipation. The effectiveness of this method has been demonstrated through parametric studies, showing reduced inter-storey deflections and minimized base displacements during strong earthquakes .
A novel approach combining base isolation with a tuned-mass-damper (TMD) located at the basement has been studied. This configuration improves seismic performance by reducing deformation, base shear, and interstory drifts. The TMD system, connected via lead-core rubber isolators, acts as both a damper and a spring, enhancing the overall stability of the structure during seismic events.
The use of Lead Rubber Bearings (LRB) as base isolators in multi-storey steel frame buildings has shown significant reductions in acceleration, inter-storey drift, and base shear. This system not only absorbs seismic energy but also mitigates the destructive effects of earthquakes, making it a viable option for enhancing the seismic resilience of steel-frame structures.
Seismic isolation systems are particularly beneficial for retrofitting historic buildings, which often have low natural vibration periods. The use of bearings and pendulums in seismic isolation systems can improve earthquake resistance without altering the structural elements of the building. Adding dampers to these systems can further reduce displacements and enhance dynamic response.
A comprehensive review of various base isolation systems, including Lead Rubber Bearings (LRB), High Damping Rubber Bearings (HDRB), and sliding bearing isolators, indicates that all these systems can effectively minimize structural damage during earthquakes. The use of energy dissipation devices and shear walls further enhances the efficiency of these systems, providing a cost-effective solution for earthquake-resistant construction.
The reviewed studies collectively demonstrate that seismic isolation systems, whether implemented at the base or at different elevations within a building, significantly enhance the seismic performance of structures. The choice of isolation system and its configuration should be tailored to the specific structural characteristics and seismic demands of the building to achieve optimal results.
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