Browsing by Author "Chien, Chia-Shang Chang"

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A study on using pre-bent steel strips as seismic energy-dissipative devices
(2009-07-10)
Wang, Yen-Po
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Chien, Chia-Shang Chang
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土木工程學系
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Department of Civil Engineering
Buckling is usually conceived as an unstable Structural behavior leading to lateral instability of axially loaded members, if not properly supported. However, a pre-bent strip Would become an excellent seismic energy-dissipative device it it is deformed in a guided direction and ratio, e. Geometrically large lateral deformation of the steel strips in buckling leads to inelastic behavior of the material and dissipates energy as a consequence. The purpose of this study is to propose a new type of seismic damper in the form of braces based on pre-bent steel strips. The nonlinear elastic stiffness of monotonously loaded pre-bent strips in both compression and tension is derived. The energy-dissipative characteristics of the proposed damping device are investigated via component tests under cyclic loads. Experimental results indicate that the force-displacement relationship of pre-bent strips in cyclic loads exhibits mechanical characteristics of displacement-dependent dampers. A series of seismic performance tests has been conducted further to verify the feasibility and effectiveness of using the proposed device as seismic dampers. Encouraging test results have been obtained, suggesting feasibility of the proposed device for earthquake-resistant design. Copyright (C) 2008 John Wiley & Sons, Ltd.
Physical system identification of an isolated bridge using seismic response data
(2009-03-01)
Huang, Ming-Chih
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Wang, Yen-Po
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Chang', Jer-Rong
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Chien, Chia-Shang Chang
;
土木工程學系
This paper develops a system identification process based on seismic response data to investigate the physical parameters of an isolated highway bridge equipped with the lead-rubber bearings (LRBs). The effects of soil-structure interaction (SSI) of the highway bridge built on pile foundations are taken into account in the analysis. Unlike many other identification methods that generally seek for the equivalent system parameters or modal parameters of the target structure, the proposed method aims at identifying physical parameters such as the pier stiffness or hysteresis of the LRB that are considered more critical and useful for health monitoring of bridges. In this study, a linear elastic model is used for the pier while a bilinear model is considered to characterize the hysteretic behavior of the LRB. The bilinear hysteretic model is in turn reduced to a backbone curve based on the Masing criterion by which the multi-valued restoring force is transformed into a single-valued function so that the computational effort of the identification process can be minimized. Numerical examples have been conducted, including the identification of Bai-Ho Bridge, which is the first seismic isolation bridge in Taiwan, to demonstrate the feasibility of the proposed technique for dynamic systems with inelastic components and SSL Copyright (C) 2008 John Wiley & Sons, Ltd.