Date of Award
Doctor of Philosophy (PhD)
Earthquakes are one of the major natural hazards that could directly cause damages to or collapse of buildings, leading to significant economic losses. In this dissertation research, analytical tools and simulation-based optimization framework are developed to improve our understanding of and the ability to design more seismic-resilient structures with passive energy dissipation systems. The main objectives of this dissertation are to (1) investigate the seismic performance of structures with energy dissipation systems and evaluate the effectiveness of damping coefficient dissipation methods using three-dimensional numerical models; (2) develop a simulation-based multi-objective optimization framework to evaluate and optimize the seismic performance of buildings with energy dissipation systems; (3) incorporate and evaluate the influence of soil-structure interaction in the performance-based seismic design of structures.
Aiming at these objectives, this dissertation consists of three related studies. In the first study, the seismic performance of structures with energy dissipation systems, specifically fluid viscous dampers (FVD), was investigated using three-dimensional (3D) numerical models. Four different damping coefficient distribution methods for FVD were extended to 3D numerical models. Then, their effectiveness in terms of improving structural seismic performance was evaluated through a series of nonlinear dynamic analysis. The seismic performance of the structure has been significantly improved by applying the FVD, and this significance of the improvement depends on the distribution of damper's damping coefficient within the 3d numerical model. Among the four different damping coefficient distribution methods, the story shear strain energy distribution (SSSED) method was found to be an optimal distribution method that can improve the inter-story drift of the structure while it can also provide the most uniformly distributed inter-story drift.
In the second study, a performance-based optimization framework for the structural design was developed that considers multiple conflicting objectives: initial material cost, structural repair cost, and record-to-record variability of ground motions. The developed optimization framework was effective in improving the seismic performance of structures. All obtained optimum designs can dramatically decrease the inter-story drift and peak floor acceleration of the structure. This study also provided a practical approach to select the optimal design variables of the energy dissipation systems. The selected design can achieve the desired performance level of the structure with moderate initial material cost, structural repair cost, and robustness measure.
In the third study, the effect of soil-structure interaction was incorporated into the optimization framework developed in the second study. Two scenarios were considered in the analysis: one with a fixed foundation, and the other one with a flexible foundation. In this study, the selection of soil properties was based on site class D. The frame with a flexible foundation was found to have a larger inter-story drift in each floor when compared to the frame with a fixed foundation. The guideline for selecting the best-performance design was developed based on the inter-story drift ratio. The improvement of the inter-story drift (compared to a bare frame without energy dissipation systems) and the uniformity of the inter-story drift, were proposed as two performance indices to evaluate the effectiveness of the selected designs.
Finally, based on findings of this dissertation work, recommendations for seismic design of buildings with energy dissipation systems and directions for future research are given.
Cheng, Yuting, "Simulation-Based Evaluation and Optimization of the Seismic Performance of Buildings with Passive Energy Dissipation System" (2019). All Dissertations. 2536.