Seismic vibration control of structures using nonlinear dampers with supporting elements

Abstract

Passive control devices such as fluid viscous dampers (FVDs) are frequently adopted to enhance energy dissipation capacity of civil engineering structures; however, seismic performance of many passive control devices with a nonlinear viscous damping characteristic remains unclear, especially when they work in conjunction with supporting elements. This thesis aims to investigate the effectiveness of different nonlinear dampers with supporting elements on improving dynamic performance of building structures; approaches to achieve effective designs of the dampers in certain types of buildings are also presented. The investigated passive control configurations include the conventional damper-brace system, and a novel truss-damper assembly proposed for seismic vibration control of atrium buildings. In addition to the FVDs, an inerter-based device termed nonlinear inertial mass damper (IMD) is also introduced and studied. The observations made in this research are expected to provide an insight into the practical design of the passive control systems with nonlinear characteristics.
A numerical time-history method is first developed in this thesis to compute the seismic response of a structure with nonlinear FVDs and supporting braces, of which the correctness and accuracy are verified through comparative studies. Based on the proposed numerical method, the effects of different design parameters of the nonlinear damper-brace system are investigated. Results indicate that a minimum brace stiffness is required to achieve a preset structural performance, and for a given brace stiffness, the velocity exponent has an insignificant effect on the maximum structural performance once the dampers are optimally designed. The robustness and reliability of the optimal damper-brace systems are evaluated by incremental dynamic analysis (IDA).
Buildings with atria can be commonly found in most cities. For seismic response mitigation of an atrium building, this study develops an approach to utilize a truss-damper configuration and a core structure inside the atrium to form a novel energy dissipation mechanism. FVDs and nonlinear IMDs are adopted as the passive control devices in the configuration; the effectiveness of these truss-damper systems is evaluated through parametric studies. Results indicate that the truss-damper systems can effectively suppress the seismic vibration of atrium buildings, and the truss-IMD systems generally outperform the truss-FVD systems.
A simplified truss-IMD-core structure model is also proposed in this thesis to further investigate the effect of the core structure stiffness on the seismic performance of atrium buildings. A multi-objective optimization approach is developed for the simplified model to minimize the peak interstory drift and story acceleration of a building simultaneously under multiple earthquakes. Numerical results from a simple structural model and a six-story building suggest superior performance of the truss- IMD system in mitigating different dynamic responses of atrium buildings.

Date of Award	Mar 2023
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Yung-Tsang Chen (Supervisor) & Bo Li (Supervisor)