An innovation brace system for dissipation of seismic energy

Zhao, Z 2016, An innovation brace system for dissipation of seismic energy, Doctor of Philosophy (PhD), Civil, Environmental and Chemical Engineering, RMIT University.

Document type: Thesis
Collection: Theses

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Title An innovation brace system for dissipation of seismic energy
Author(s) Zhao, Z
Year 2016
Abstract Designing safe and robust structures to withstand earthquake forces has always been a common goal among structural engineers and researchers. Earthquake and strong wind effect are the two major big design challenges for the structural engineer. The Christchurch and Tohoku earthquakes reminded us again the powerful destructiveness of earthquakes. In order to absorb the energy response of the multilevel buildings during earthquake, energy absorbing passive damper systems is commonly used all over the world.

This dissertation reports a systematic study on developing an economic effective solution for the design and retrofit for the new or existing structures. The attention is focused on developing a upper toggle- brace-damper system configuration that substantially magnifies the effectiveness of damping devices under small structural drifts. Through the toggle arrangement, damper travel is magnified while effective damper stiffness is found to increase up to three times to improve seismic performance of the structures. It is further shown that this upper toggle-brace-damper system configuration, architecturally, also provides more usable space for building occupants. In moderate earthquakes, major structural elements such as beams and columns can be protected; while in large earthquakes life-safety can be enhanced. An effective energy dissipation system can result in higher levels of safety and comfort, and can also lead to considerable savings in the total cost of a building. A comprehensive economical design methodology suitable for design engineers will be proposed.

An emerging computational analysis method Incremental Dynamic Analysis (IDA) was employed in the analysis to validate with a series of scaled seismic records. It is observed that this method is to estimate seismic demand hazard accurately and efficiently. We illustrate the IDA method through three benchmark steel nonlinear structures designed for SAC Phase II Steel Project for the Los Angeles, California [1]. A nonlinear structural analysis were carried out using the computer program OPENSEES to obtain the IDA result. The mean annual frequency (MAFs) exceedance will be found out from the IDA results.

Finally, a probabilistic seismic hazard analysis (PSHA) calculation of three steel benchmark structures will be presented. In this probabilistic demand hazard calculation, only the first-mode spectral acceleration was considered. In this thesis, the ground motion intensity is characterized by, say, , the spectral pseudo-acceleration corresponding to first-mode elastic vibration period and 5% damping ratio is use to consider. The seismic result get from the numerically analysis result from IDA and the benchmarks steel structure location and the potential future earthquakes probability to predict the potential shaking intensity caused by the future earthquake events. The MAFs of exceedance with the probabilistic percentage for the three buildings within 50 years was found out to show the upper toggle-brace-damper system is the most efficiency energy dissipation devices to install to absorb the energy during the seismic events.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Civil, Environmental and Chemical Engineering
Subjects Earthquake Engineering
Powder and Particle Technology
Keyword(s) OPENSEES
Incremental Dynamic Analysis (IDA)
Upper toggle-brace-damper system
Passive energy dissipation
Probabilistic seismic hazard analysis calculation
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Created: Wed, 09 Nov 2016, 12:23:18 EST by Keely Chapman
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