TY - JOUR

T1 - Optimizing seismic performance of base-isolated buildings with mass and stiffness variations under near and far fault ground motions

AU - Kiral, Adnan

AU - Tonyali, Zeliha

AU - Elias, Said

N1 - Publisher Copyright: © 2025 Institution of Structural Engineers

PY - 2025/6

Y1 - 2025/6

N2 - Extensive research has been conducted on base-isolated structures; however, the long-term effects of mass and stiffness variations, resulting from factors such as structural modifications, equipment installations, or isolator deterioration, are often overlooked. These changes can alter the building's dynamic properties, leading to excessive seismic accelerations and bearing displacements that exceed design expectations. To mitigate these effects, viscous dampers at the base offer a promising solution, but optimizing their damping coefficients is critical for balancing multiple performance objectives. This study introduces two novel iterative-based design methodologies (DMs) that simultaneously optimize drift and acceleration. A nine-story base-isolated building is analysed in MATLAB under various near-fault (NF) and far-fault (FF) ground motion scenarios. Numerical results demonstrate that the optimized system (Sysopt) effectively reduces maximum Laminated Rubber Bearing (LRB) displacement and Roof Floor (RF) acceleration, achieving reductions of up to 17 % and 13 %, respectively, under mass variations, while non-optimized systems lead to increases of up to 127 % and 97 %. Under reduced LRB stiffness, Sysoptmaintains LRB displacement within acceptable limits and reduces RF acceleration by up to 13 %, whereas non-optimized systems result in increases of up to 63 % in the LRB displacement and 46 % in the RF acceleration. In the most critical scenario, simultaneous mass increase and stiffness reduction, Sysoptsuccessfully controls LRB displacement and reduces RF acceleration by up to 22 %, while non-optimized systems experience increases of up to 215 % in the LRB displacement and 144 % in the RF acceleration. Besides, system modifications have varying impacts on base shear forces under both FF and NF GMs. Overall, while non-optimised system increases base shear forces up to 183 %, the optimized system consistently lowers base shear, confirming its effectiveness across all seismic scenarios. These findings highlight the significant impact of mass and stiffness variations on seismic performance and underscore the necessity of advanced vibration control strategies to ensure structural resilience.

AB - Extensive research has been conducted on base-isolated structures; however, the long-term effects of mass and stiffness variations, resulting from factors such as structural modifications, equipment installations, or isolator deterioration, are often overlooked. These changes can alter the building's dynamic properties, leading to excessive seismic accelerations and bearing displacements that exceed design expectations. To mitigate these effects, viscous dampers at the base offer a promising solution, but optimizing their damping coefficients is critical for balancing multiple performance objectives. This study introduces two novel iterative-based design methodologies (DMs) that simultaneously optimize drift and acceleration. A nine-story base-isolated building is analysed in MATLAB under various near-fault (NF) and far-fault (FF) ground motion scenarios. Numerical results demonstrate that the optimized system (Sysopt) effectively reduces maximum Laminated Rubber Bearing (LRB) displacement and Roof Floor (RF) acceleration, achieving reductions of up to 17 % and 13 %, respectively, under mass variations, while non-optimized systems lead to increases of up to 127 % and 97 %. Under reduced LRB stiffness, Sysoptmaintains LRB displacement within acceptable limits and reduces RF acceleration by up to 13 %, whereas non-optimized systems result in increases of up to 63 % in the LRB displacement and 46 % in the RF acceleration. In the most critical scenario, simultaneous mass increase and stiffness reduction, Sysoptsuccessfully controls LRB displacement and reduces RF acceleration by up to 22 %, while non-optimized systems experience increases of up to 215 % in the LRB displacement and 144 % in the RF acceleration. Besides, system modifications have varying impacts on base shear forces under both FF and NF GMs. Overall, while non-optimised system increases base shear forces up to 183 %, the optimized system consistently lowers base shear, confirming its effectiveness across all seismic scenarios. These findings highlight the significant impact of mass and stiffness variations on seismic performance and underscore the necessity of advanced vibration control strategies to ensure structural resilience.

KW - Base isolation

KW - LRB

KW - Mass and stiffness variation

KW - Near and far field ground motions

KW - Optimized design methodologies

KW - Structural seismic control

KW - Viscous damper

UR - http://www.scopus.com/inward/record.url?scp=105003776672&partnerID=8YFLogxK

U2 - 10.1016/j.istruc.2025.109026

DO - 10.1016/j.istruc.2025.109026

M3 - Article

AN - SCOPUS:105003776672

VL - 76

JO - Structures

JF - Structures

SN - 2352-0124

M1 - 109026

ER -