Available at: https://digitalcommons.calpoly.edu/theses/3381
Date of Award
6-2026
Degree Name
MS in Civil and Environmental Engineering
Department/Program
Civil and Environmental Engineering
College
College of Engineering
Advisor
Giovanni De Francesco
Advisor Department
Civil and Environmental Engineering
Advisor College
College of Engineering
Abstract
This study reviews the state of the art of MSI and evaluates a practical framework for preliminary design using coupling coefficients. A database of 155 research documents is compiled and classified into analytical, mixed numerical, computational, experimental, and miscellaneous studies. The review identifies major research trends, common modeling approaches, important design parameters, and remaining limitations. In addition, 16 representative MSI building projects are reviewed. These applications show that MSI is most often used for retrofit, vertical expansion, mixed-use buildings, over-track construction, and buildings with major functional or structural discontinuities. The study then examines the Coupling Coefficients (CCs) Method as a practice-oriented approach for estimating the seismic response of mid-story isolated buildings. In this method, the podium and isolated tower are first analyzed as separate structures, and coupling coefficients are then used to relate those demands to the response of the full MSI system. Nonlinear time-history analyses are performed using simplified single-, two-, and three-degree-of-freedom models with a triple friction pendulum (TFP) isolator behavior. The analysis considers 7000 ground-motion records, multiple isolated mass ratios, structural periods, damping levels, and ductility levels. The results show that the isolated mass ratio and the period or stiffness relationship between the podium and isolation system are major factors affecting the coupling coefficients. In contrast, structural damping and isolator ductility have less direct influence on the coefficient trends over the ranges considered. These findings support the use of coupling coefficients as a possible bridge between detailed nonlinear analysis and simplified preliminary design. Future work should develop analytical prediction equations for these coefficients, validate them with experimental and building-response data, and evaluate how they could be incorporated into the current ASCE-7 design workflow for seismically isolated structures.