Evaluation and Comparison of Structural Stability after Using Dampers and Isolators

This study aims to experimentally assess the simultaneous effectiveness of lead-core rubber base isolators and linear viscous dampers in enhancing the seismic stability of mid-rise steel frame structures. An eight-story steel flexural frame model, scaled ۱:۴ and designed per the ۴th edition of the ۲۸۰۰ Code for Soil Type III, was subjected to dynamic testing using a two-dimensional shake table. The experiment was conducted under fifteen real earthquake accelerograms. First, the model was tested without control devices. Then, four lead-core rubber isolators were installed at the base and two linear viscous dampers on the second and fourth floors. MEMS accelerometers and laser displacement sensors recorded the seismic responses. A paired t-test was used to statistically compare the stability index before and after the control intervention, with significance set at p<۰.۰۵. The results demonstrated a statistically significant improvement in structural stability. The average stability index increased by ۱۲.۷%, with all ۱۵ records showing consistent positive differences (Δ ranging from ۰.۰۰۷۰ to ۰.۰۱۲۶). The paired t-test yielded t(۱۴) = ۲۱.۷۶۹, p < ۰.۰۰۰۱, and a Cohen’s d ≈ ۵.۵, indicating a very large effect size. Time-history analysis revealed a reduction in interstory drift of up to ۳۰% and a substantial decline in floor accelerations, bringing the structure into the code-defined serviceability range. The system displayed consistent performance across a spectrum of seismic inputs, with a coefficient of variation at ۱۸%, indicating high reliability. Economically, the system reduced the demand for secondary reinforcement, offsetting part of its installation cost. The combined use of base isolators and viscous dampers significantly improves seismic performance by reducing drift and accelerations, while ensuring structural stability and economic feasibility. This integrated approach presents a reliable and sustainable solution for enhancing the seismic resilience of mid-rise buildings.This study aims to experimentally assess the simultaneous effectiveness of lead-core rubber base isolators and linear viscous dampers in enhancing the seismic stability of mid-rise steel frame structures. An eight-story steel flexural frame model, scaled ۱:۴ and designed per the ۴th edition of the ۲۸۰۰ Code for Soil Type III, was subjected to dynamic testing using a two-dimensional shake table. The experiment was conducted under fifteen real earthquake accelerograms. First, the model was tested without control devices. Then, four lead-core rubber isolators were installed at the base and two linear viscous dampers on the second and fourth floors. MEMS accelerometers and laser displacement sensors recorded the seismic responses. A paired t-test was used to statistically compare the stability index before and after the control intervention, with significance set at p<۰.۰۵. The results demonstrated a statistically significant improvement in structural stability. The average stability index increased by ۱۲.۷%, with all ۱۵ records showing consistent positive differences (Δ ranging from ۰.۰۰۷۰ to ۰.۰۱۲۶). The paired t-test yielded t(۱۴) = ۲۱.۷۶۹, p < ۰.۰۰۰۱, and a Cohen’s d ≈ ۵.۵, indicating a very large effect size. Time-history analysis revealed a reduction in interstory drift of up to ۳۰% and a substantial decline in floor accelerations, bringing the structure into the code-defined serviceability range. The system displayed consistent performance across a spectrum of seismic inputs, with a coefficient of variation at ۱۸%, indicating high reliability. Economically, the system reduced the demand for secondary reinforcement, offsetting part of its installation cost. The combined use of base isolators and viscous dampers significantly improves seismic performance by reducing drift and accelerations, while ensuring structural stability and economic feasibility. This integrated approach presents a reliable and sustainable solution for enhancing the seismic resilience of mid-rise buildings.

کلیدواژه ها:

Lead-core rubber base isolator ، Passive seismic control ، Nonlinear time history analysis ، Linear viscous damper ، Interstory drift ، Structural stability ، Earthquake engineering