An Improved FPS Isolator for Seismic Mitigation on Steel Structure

2002 ◽  
Author(s):  
C. S. Tsai ◽  
Tsu-Cheng Chiang ◽  
Chia-Kuan Cheng ◽  
Wen-Shin Chen ◽  
Chih-Wei Chang
Keyword(s):  
Spherical Surface ◽  
Structural Response ◽  
Steel Structure ◽  
Experimental Results ◽  
Shaking Table ◽  
Element Formulation ◽  
Shaking Table Tests ◽  
Surface Type ◽  
Sliding Interface ◽  
Seismic Loadings

Structure equipped with base isolators to decouple the superstructure from its foundation has been recognized as an effective and feasible way to mitigate structural response subjected to seismic loadings. In this study, a new lubricant material for the FPS isolator has been developed. The experimental results from shaking table tests show that the acceleration responses of floors of a structure isolated by the FPS isolators coated with the new Teflon composite can be lessened within a desirable range, and the steel structure with the FPS isolators moves nearly as rigid body motions during earthquakes. To verify the durability of the FPS isolators, the component tests of sliding interface coated with advanced Teflon composite and shaking table tests of steel structure with the FPS isolators subjected to hundreds of earthquake events were performed in this study. The experimental results demonstrate that the advanced Teflon composite can sustain hundreds of reversal loadings, therefore, it can be adopted to lubricate the sliding interface of the FPS isolators. Furthermore, a simplified and a finite element formulation for bilateral-spherical-surface-type FPS have been proposed in this study. The numerical results show that the proposed formulation can well predict the dynamic response of structure with bilateral-spherical-surface-type FPS than the formulation proposed by S. Okamura et at.

Experimental Study of a Multiple Bay Structure Isolated With Hybrid Bearings

2003 ◽  
Author(s):  
C. S. Tsai ◽  
Bo-Jen Chen ◽  
Tsu-Cheng Chiang ◽  
Guan-Hsing Lee
Keyword(s):  
Earthquake Engineering ◽  
Base Isolation ◽  
Steel Structure ◽  
Seismic Energy ◽  
Shaking Table ◽  
Element Formulation ◽  
Shaking Table Tests ◽  
Seismic Responses ◽  
Promising Tool ◽  
Rubber Bearings

In conventional earthquake resistance design approach (the ductility-design philosophy), the energy dissipation mechanism is based on plastic deformations at scattered locations in the structure. However, this can produce permanent damage to the joints as well as the larger interstory displacements. In recently years, the base isolation technology has been adopted as a feasible and attractive way in improving seismic resistance of structures. It can shift the natural periods of structures away from the rich periods contents of earthquake motions, but also provide considerable supplemental damping to dissipate seismic energy transmitted into structures during earthquakes. In this paper, uniaxial, biaxial, and triaxial shaking table tests are performed to study the seismic behavior of a 0.4-scale three-story isolated steel structure in the National Center for Research on Earthquake Engineering in Taiwan. Experimental results demonstrate that structures with hybrid rubber bearings can actually decrease the seismic responses of the superstructure. It has been proved through the shaking table tests that the rubber bearing is a very promising tool to enhance the seismic resistibility of structures. Moreover, it is illustrated that the proposed analytical model and finite element formulation in this paper can well predict the mechanical behavior of rubber bearings and seismic responses of the base-isolated structures.

Seismic Responses of a Full-Scale Steel Structure Using Multi-Curved Buckling Restrained Braces

2007 ◽  
Author(s):  
C. S. Tsai ◽  
Wen-Shin Chen ◽  
Yung-Chang Lin ◽  
Chen-Tsung Yang ◽  
Ching-Pei Tsou
Keyword(s):  
Earthquake Engineering ◽  
Ground Motions ◽  
Steel Structure ◽  
Full Scale ◽  
Experimental Results ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Seismic Responses ◽  
Buckling Restrained Brace ◽  
Buckling Restrained Braces

Since 1970’s, many types of braces have been developed without buckling under large compressive forces called the buckling restrained brace BRB, or unbonded brace. Recently, many investigators have made a lot of efforts to look into the behaviors of the buckling restrained brace under quasi-static forces, but few experimental results about shaking table tests of a structure with buckling restrained braces have been published. Therefore, in this study, a series of shaking table tests were carried out in the National Center for Research on Earthquake Engineering, and the issue is focused on observing the seismic responses of a full-scale three-story steel structure with multi-curved reinforced buckling restrained braces subjected to earthquake ground motions. Experimental results show that most column shear forces and displacements had been reduced by the RBRB devices. In addition, the absolute accelerations had also been favorably diminished during earthquakes. It can be proven that the proposed device is suitable for applications of seismic mitigation for structures.

Shaking Table Tests of a Full Scale Steel Structure Isolated With MFPS

2003 ◽  
Author(s):  
C. S. Tsai ◽  
Tsu-Cheng Chiang ◽  
Bo-Jen Chen
Keyword(s):  
Earthquake Engineering ◽  
Stress Responses ◽  
Passive Control ◽  
Base Isolation ◽  
Experimental Results ◽  
Shaking Table ◽  
Element Formulation ◽  
Shaking Table Tests ◽  
Pendulum System ◽  
Residual Displacements

The base isolation, a kind of passive control technology, has been proved as a very efficient way to ensure the safety of a structure during severe earthquakes both from theoretical study and experimental effort. In general, the base isolation can be classified into two groups, which are sliding type and elastomeric type isolator. In this study, a new base isolator called as Multiple Friction Pendulum System (MFPS) has been proposed. The lubricant material, articulated slider and doubled concave sliding interfaces of MFPS are quite different from that proposed by V. Zayas in 1987. In this study, the MFPS isolator has been equipped beneath each column of a three-story structure at the National Center for Research on Earthquake Engineering to demonstrate its seismic resistance capability. The experimental results from shaking table tests of the 1940 El Centro, 1995 Kobe and 1999 Chi-Chi earthquake show that the proposed isolator can reduce the undesirable seismic response of the structure by lengthening the fundamental period of the structure during earthquakes. The experimental results indicate that the acceleration response of each floor can be lessened significantly as compared with those of the bare structure, and that the stress responses of structural components are limited in the certain range during severe earthquakes. Furthermore, the residual displacements of base isolators are negligible. Therefore, it is shown evidently that the proposed isolator can always bring the base-isolated structure to its initial position after an earthquake. Based on the previous observations, the proposed isolator can be adopted as an effective tool for upgrading the seismic resistibility of a structure. A finite element formulation for the MFPS is also proposed to simulate its mechanical behavior during earthquakes.

scholarly journals Experimental Assessment of a Skyhook Semiactive Strategy for Seismic Vibration Control of a Steel Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Nicola Caterino ◽  
Mariacristina Spizzuoco ◽  
Antonio Occhiuzzi ◽  
Antonio Bonati
Keyword(s):  
Continuous Monitoring ◽  
Structural Response ◽  
Steel Structure ◽  
Shaking Table ◽  
Seismic Protection ◽  
Damping Properties ◽  
Shaking Table Tests ◽  
Seismic Vibration ◽  
Structural Vibrations ◽  
Damping Force

Sky-hook damping is one of the most promising techniques for feedback control of structural vibrations. It is based on the idea of connecting the structure to an ideal fixed point of the space through passive dissipative devices. Herein the benefit of semiactive (SA) sky-hook (SH) damping is investigated for seismic protection of a two-storey steel frame via shaking table tests. This kind of SA control is achieved implementing a continuous monitoring of selected structural response parameters and using variable dampers. The damping properties of the latter are changed in real-time so as to make the force provided by the damper match the desired SH damping force as closely as possible. To this aim, two prototype magnetorheological dampers have been installed at the first level of the frame and remotely driven by a SH controller. The effectiveness of the control strategy is measured as response to reduction in terms of floor accelerations and interstory drift in respect to the uncontrolled configuration. Two different calibrations of the SH controller have been tested. The experimental results are deeply discussed in order to identify the optimal one and understand the motivations of its better performance.

Experimental Study for a New Energy Dissipation Device: Multiple-Direction Damper

2002 ◽  
Author(s):  
C. S. Tsai ◽  
L. L. Chung ◽  
T. C. Chiang ◽  
B. J. Chen ◽  
W. S. Chen
Keyword(s):  
Energy Dissipation ◽  
Passive Control ◽  
Steel Structure ◽  
Experimental Results ◽  
Shaking Table ◽  
New Energy ◽  
Seismic Loadings ◽  
Control Technologies ◽  
Energy Dissipation Devices ◽  
Energy Absorbing

The way of passive control technologies has been recognized as an excellent method to mitigate seismic responses of structures during seismic excitations. In general, the energy dissipation devices based on their own mechanical property can be divided into two categories, which are velocity-dependent and displacement-dependent devices. In this study, a new displacement-dependent device which is called multiple-direction damper is proposed. The proposed damper has numerous advantages: (1) the fabrication of this energy-absorbing device is effortless; (2) the construction of the energy-absorbing system is easy; (3) it is simple to install the device into a structure; (4) the material used for this damper is easy to obtain; and (5) if any damage occurs in this damper during strong excitations, this energy-absorbing device can be replaced easily to recover its energy dissipation capacity. Experimental results from component tests show that the proposed damper provides significant energy-absorbing capacity. Furthermore, the multiple-direction dampers have also been equipped into a 5-story steel structure to demonstrate its efficiency on seismic mitigation. The experimental results from shaking table tests indicate that most of earthquake-induced energy imparted into the structure is dissipated by the proposed dampers. In the meanwhile, the seismic loadings imposing on the structure with devices can be reduced effectively as compared with those of the bare structure. Therefore, the multiple-direction damper can be recognized as an effective tool to assure the safety of structure under strong ground motions.

Finite element formulation and shaking table tests of direction-optimized-friction-pendulum system

2008 ◽  
Vol 30 (9) ◽  
pp. 2321-2329 ◽  
Author(s):  
C.S. Tsai ◽  
Po-Ching Lu ◽  
Wen-Shin Chen ◽  
Tsu-Cheng Chiang ◽  
Chen-Tsung Yang ◽  
...  
Keyword(s):  
Finite Element ◽  
Shaking Table ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Shaking Table Tests ◽  
Pendulum System ◽  
Friction Pendulum ◽  
Friction Pendulum System

Response Control Performance Evaluation of MR Damper by Shaking Table Tests and Real-Time Hybrid Tests

2008 ◽  
Vol 56 ◽  
pp. 212-217 ◽  
Author(s):  
Hideo Fujitani ◽  
Hiroaki Sakae ◽  
Mai Ito ◽  
Takeshi Hiwatashi
Keyword(s):  
Real Time ◽  
Sliding Mode ◽  
Structural Response ◽  
Mr Damper ◽  
Shaking Table ◽  
Magnetorheological Damper ◽  
Control Force ◽  
Building Structures ◽  
Shaking Table Tests ◽  
Hybrid Test

Magnetorheological damper (MR damper) has been expected to control the response of civil and building structures in recent years, because of its large force capacity and variable force characteristics. In this paper, a series of real-time hybrid test was conducted and the results of real time hybrid tests were compared to those of shaking table tests. To determine the control force of the MR damper, skyhook control and sliding mode control theory were employed. As the results, the validity of real-time hybrid test was verified. This paper describes the capability of MR damper to control the structural response.

Shaking Table Tests of Full Scale Base-Isolated Structures

2002 ◽  
Author(s):  
C. S. Tsai ◽  
B. J. Chen ◽  
T. C. Chiang
Keyword(s):  
Structural Control ◽  
Control Strategies ◽  
Steel Structure ◽  
Seismic Energy ◽  
Full Scale ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Natural Period ◽  
Rubber Bearing ◽  
Rubber Bearings

Conventional earthquake resistant designs depend on strengthen and ductility of the structural components to resist induced forces and to dissipate seismic energy. However, this can produce permanent damage to the joints as well as the larger interstory displacements. In recently years, many studies on structural control strategies and devices have been developed and applied in U. S. A., Europe, Japan, and New Zealand. The rubber bearing belongs to one kind of the earthquake-proof ideas of structural control technologies. The installation of rubber bearings can lengthen the natural period of a building and simultaneously reduce the earthquake-induced energy trying to impart to the building. They can reduce the magnitude of the earthquake-induced forces and consequently reduce damage to the structures and its contents, and reduce danger to its occupants. This paper is aimed at studying the mechanical behavior of the stirrup rubber bearings (SRB) and evaluating the feasibility of the buildings equipped with the stirrup rubber bearings. Furthermore, uniaxial, biaxial, and triaxial shaking table tests are conducted to study the seismic response of a full-scale three-story isolated steel structure. Experimental results indicate that the stirrup rubber bearings possess higher damping ratios at higher strains, and that the stirrup rubber bearings provide good protection for structures. It has been proved through the full-scale tests on shaking table that the stirrup rubber bearing is a very promising tool to enhance the seismic resistibility of structures.

scholarly journals Examining the seismic behaviour of partially saturated sand using centrifuge shaking table tests

2019 ◽  
Vol 92 ◽  
pp. 17002
Author(s):  
Zitao Zhang ◽  
Jianzhang Xiao ◽  
Yingqi Wei ◽  
Hong Cai ◽  
Jianhui Liang ◽  
...  
Keyword(s):  
Effective Stress ◽  
Experimental Results ◽  
Shaking Table ◽  
Degree Of Saturation ◽  
Saturated Sand ◽  
Shaking Table Tests ◽  
Seismic Behaviour ◽  
Liquefaction Resistance ◽  
Partially Saturated ◽  
Partially Saturated Sand

Similar to fully saturated sand, the partially saturated sand can also liquefy under certain conditions during earthquakes. This study aims to characterize the seismic behaviour of partially saturated sand. Centrifuge shaking table tests were performed using the IWHR horizontal-vertical centrifuge shaker. The experimental results indicate that the liquefaction resistance of the partially saturated sand increases with decreasing the degree of saturation and with increasing the initial effective stress right before shaking. The boundary between the liquefied and un-liquefied sand becomes deeper and deeper during shaking.

Shaking Table Test of Structure With Reinforced Buckling Restrained Braces

2005 ◽  
Author(s):  
C. S. Tsai ◽  
Wen-Shin Chen ◽  
Kuei-Chi Chen
Keyword(s):  
Shaking Table Test ◽  
Dynamic Testing ◽  
Steel Structure ◽  
Shaking Table ◽  
Test Results ◽  
Buckling Restrained Brace ◽  
Steel Core ◽  
Shaking Table Testing ◽  
Buckling Restrained Braces ◽  
Seismic Loadings

The traditional brace elements will buckle when subjected to severe earthquakes. Many researchers have been trying to overcome this disadvantage of the traditional brace element since 1970’s. Many types of braces have been developed without buckling under large compressive forces called the buckling restrained brace BRB, or unbonded brace. This type brace includes a steel core, a case that encases the steel core and brace projection, and can enhance both the stiffness and hysteretic damping of a structure to resist seismic loadings. Recently, some investigators have carried out the researches focusing on the procedure of designing buckling restrained braces, quasi dynamic testing and the methods of the connection between the buckling restrained brace and main structure. But, these results can not reflect the effects of the structure with buckling restrained braces during earthquakes. Therefore, the shaking table testing should be done to examine the effects of new BRBs on the seismic responses of a structure. In this study, the reinforced buckling restrained braces were installed on a three-story scaled steel structure in Feng Chia University to perform a series of shaking table tests. The test results illustrate that the new unbond braces provide good protection for structures during earthquakes.

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