Seismic Responses of a Full-Scale Steel Structure Using Multi-Curved 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.

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Experimental Study of a Multiple Bay Structure Isolated With Hybrid Bearings

Seismic Engineering ◽

10.1115/pvp2003-2106 ◽

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.

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Shaking Table Tests of Full Scale Base-Isolated Structures

Seismic Engineering, Volume 2 ◽

10.1115/pvp2002-1453 ◽

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.

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An Improved FPS Isolator for Seismic Mitigation on Steel Structure

Seismic Engineering, Volume 2 ◽

10.1115/pvp2002-1452 ◽

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.

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Mathematical modeling and full-scale shaking table tests for multi-curve buckling restrained braces

Earthquake Engineering and Engineering Vibration ◽

10.1007/s11803-009-9004-9 ◽

2009 ◽

Vol 8 (3) ◽

pp. 359-371 ◽

Cited By ~ 8

Author(s):

C. S. Tsai ◽

Yungchang Lin ◽

Wenshin Chen ◽

H. C. Su

Keyword(s):

Mathematical Modeling ◽

Full Scale ◽

Shaking Table ◽

Shaking Table Tests ◽

Buckling Restrained Braces

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Shaking Table Test of Structure With Reinforced Buckling Restrained Braces

Volume 8: Seismic Engineering ◽

10.1115/pvp2005-71166 ◽

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

Seismic Engineering ◽

10.1115/pvp2003-2100 ◽

2003 ◽

Cited By ~ 8

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.

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