Seismic base isolation for steel structures

1985 ◽  
Vol 12 (1) ◽  
pp. 73-81
Author(s):  
S. F. Stiemer ◽  
B. B. Barwig
Keyword(s):  
Base Isolation ◽  
Steel Structures ◽  
Experimental Tests ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Experimental Investigations ◽  
Steel Buildings ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Base Isolation System

Base isolation is a strategy for a design of buildings in areas where seismic loads govern. It enables the reduction of earthquake excitation to an acceptable level, without an increase of structural acceleration. This paper presents the results of the experimental investigations of various schemes of first-storey designs for steel buildings with base isolation.A scaled-down steel frame building was used for the shaking table tests, which were conducted in the Earthquake Simulator Laboratory of the University of British Columbia. The base-storey design was altered while the dynamic response of the frame was recorded. The base isolation consisted of steel roller bearings with parallel steel yield rings, to limit excessive displacements and provide wind restraint.The proposed base storey is substantially different from conventional solutions. The variation in the base-storey design was aimed at the elimination of the blind base storey or double foundation in order to increase the economy of the base-isolation system. The experimental tests showed suitable design approaches, and analytical studies to optimize them will follow.It was verified that uncoupling of buildings from the earthquake ground motion is relatively simple to achieve. Certain restraint is required to resist wind and other horizontal loads. This is usually achieved by mechanical fuses or energy absorbers. A solid state energy absorber was used in the described tests. Key words: base-isolation system for buildings, earthquake-resistant steel structures, experimental investigations, retrofit system.

Seismic Design and Characterization of a New Isolation System for High Voltage Circuit Breakers Based on Wire-Rope Devices

2015 ◽  
Author(s):  
Renato Giannini ◽  
Silvia Alessandri ◽  
Fabrizio Paolacci ◽  
Marialaura Malena
Keyword(s):  
Base Isolation ◽  
Circuit Breaker ◽  
Experimental Tests ◽  
Shaking Table ◽  
Circuit Breakers ◽  
Paper Briefly ◽  
Isolation System ◽  
Wire Ropes ◽  
Base Isolation System

This paper briefly describes the design and the characterization of a new base isolation system for the seismic protection of HV ceramics circuit breakers, in order to be qualified according to the standard CEI 62271-207. The solution adopted is based on the use of Wire Ropes. Accurate numerical analyses and experimental tests performed on a typical HV breaker upon a shaking table demonstrated the effectiveness of the proposed solution. An on-site installation in several Italian substations of this system has permitted to verify the simplicity and rapidity of the intervention necessary for the seismic upgrading of the circuit breaker.

scholarly journals Earthquake simulation testing of a stepping frame with energy-absorbing devices

1977 ◽  
Vol 10 (4) ◽  
pp. 196-207 ◽  
Author(s):  
J. M. Kelly ◽  
D. F. Tsztoo
Keyword(s):  
Base Isolation ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Earthquake Simulation ◽  
Isolation System ◽  
Steel Bars ◽  
Base Isolation System ◽  
Simulation Testing ◽  
Ground Motion Records ◽  
Energy Absorbing

Results are reported of earthquake simulation tests on a model frame with a partial base isolation system that includes energy-absorbing devices. The isolation system was modeled on a stepping bridge concept developed for the New Zealand Railways, and the energy-absorbing devices, based on the plastic torsion of rectangular mild steel bars, functioned only when the frame base lifted off the foundation. Two series of tests using scaled accelerations from the El Centro N-S 1940 and Pacoima Dam 1971 earthquake ground motion records were used as input to the shaking table on which the tests were performed. Results from these tests are compared to those from earlier tests on an identical frame with the foundation (1) anchored as in conventional design, and (2) permitted to uplift freely. The response of
the frame with the energy-absorbing devices installed was improved over
that of both the fixed frame and the frame allowed to uplift freely for the El Centro accelerations. Although the results are not as favourable for the Pacoima Dam input, the feasibility of the energy-absorbing devices associated with a partial base isolation system is established as an alternative to anchored frames and frames allowed to uplift freely.

scholarly journals Polymeric Bearings as a new base isolation system suitable for mitigating machine-induced vibrations

2018 ◽  
Vol 211 ◽  
pp. 17001 ◽  
Author(s):  
Tomasz Falborski ◽  
Robert Jankowski
Keyword(s):  
Base Isolation ◽  
Excitation Frequency ◽  
Hysteresis Loops ◽  
Shaking Table ◽  
Damping Properties ◽  
Structural Vibrations ◽  
Isolation System ◽  
Equivalent Damping ◽  
Flexible Polymer ◽  
Base Isolation System

The present paper summarizes the preliminary results of the experimental shaking table investigation conducted in order to verify the effectiveness of a new base isolation system consisting of Polymeric Bearings in reducing strong horizontal machine-induced vibrations. Polymeric Bearing considered in the present study is a prototype base isolation system, which was constructed with the use of a specially prepared flexible polymer with improved damping properties. Dynamic oscillatory tests, during which a concrete base slab supported by four Polymeric Bearings was subjected to horizonal sinusoidal excitations characterized by different frequencies and amplitudes, were conducted in order to determine the damping properties of Polymeric Bearings and their effectiveness in mitigating structural vibrations. Equivalent damping ratios for every excitation frequency considered were determined using the experimentally obtained hysteresis loops. Final conclusions are presented and the results discussed.

Reduction of Seismic Response of Mechanical System by Base Isolation System With Friction Bearing

2007 ◽  
Author(s):  
Shigeru Aoki ◽  
Yuji Nakanishi ◽  
Kazutoshi Tominaga ◽  
Takeshi Otaka ◽  
Tadashi Nishimura ◽  
...  
Keyword(s):  
Mechanical System ◽  
Seismic Response ◽  
Base Isolation ◽  
Low Frequency ◽  
Simulation Method ◽  
Shaking Table ◽  
Restoring Force ◽  
Isolation System ◽  
Friction Bearing ◽  
Base Isolation System

Reduction of seismic response of mechanical system is important problem for aseismic design. Some types of base isolation systems are developed and used in actual base of buildings and floors in buildings for reduction of seismic response of mechanincal system. In this paper, a base isolation system utilizing bearing with friction and restoring force of bearing is proposed. Friction bearing consists of two plates having spherical concaves and oval type metal or spherical metal with rubber. First, effectiveness of the base isolation system is examined experimentally. Using artificial time histories, the isolated table is shaken on the shaking table. The maximum value of response is reduced and sum of squares of response is significantly reduced. Power spectrum is significantly reduced in almost of all frequency regions, except for very low frequency region. Next, in order to examine reduction of seismic response of actual mechanical system, a console rack is set on the isolated plate. Seismic response is also significantly reduced. Finally, obtained results of experiment are examined by simulation method. An analytical model considering friction and restoring force is used. From simulation method, effectiveness of the proposed base isolation system is demonstrated.

The Material Behavior and Isolation Benefits of Ball Pendulum System

2006 ◽  
Author(s):  
C. S. Tsai ◽  
Ching-Pei Tsou ◽  
Yung-Chang Lin ◽  
Mei-Ju Chen ◽  
Wen-Shin Chen
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Material Behavior ◽  
Shaking Table ◽  
Ground Acceleration ◽  
Isolation System ◽  
Pendulum System ◽  
Damping Material ◽  
Base Isolation System ◽  
Damping Materials

Earthquake ground motions often result in significant seismic disasters. Strong ground motions will not only cause damage, but may also cause the collapse of structures. People have to face up the suffering from the earthquake damage, and the indirect loss which may be more serious than the damage itself. For example, the antique breaks in museum, and the equipment damages in hi-tech industries are often in huge loss. Therefore, in addition to promoting the earthquake-resistant capacity of a structure, it is also important to ensure the safety of the ancient valuable objects and the instruments in structures. For this reason, this study is aimed at a new damped rolling type base isolation system named the ball pendulum system (BPS) to be installed under the motion sensitive equipment and proceeding all related studies. The isolation device can isolate earthquake from buildings or equipments in any direction by rolling motions and damping materials. This study has conducted a series of component tests and shaking table tests for examining the behaviors of materials and earthquake proof benefits. From the experiment results, it is found that this device can reduce more than 80% of acceleration response under earthquakes with peak ground acceleration of 450 gal. So, the new rolling isolation system with a damping material can be recognized as a feasible and promising way in mitigating the seismic response of equipment.

scholarly journals Suitable Friction Sliding Materials for Base Isolation of Masonry Buildings

2012 ◽  
Vol 19 (6) ◽  
pp. 1327-1339 ◽  
Author(s):  
Radhikesh P. Nanda ◽  
Pankaj Agarwal ◽  
Manish Shrikhande
Keyword(s):  
Base Isolation ◽  
Low Cost ◽  
Analytical Investigation ◽  
Seismic Protection ◽  
Experimental Investigations ◽  
Masonry Buildings ◽  
Isolation System ◽  
Sliding Interfaces ◽  
The Coefficient Of Friction ◽  
Base Isolation System

A feasibility study of friction base isolation system for seismic protection has been performed. Four different sliding interfaces, namely, green marble/High Density Poly Ethylene (HDPE), green marble/green marble, green marble/geosynthetic, and green marble/ rubber layers have been studied through experimental and analytical investigations. The experimental investigations show that the coefficient of friction values of these interfaces lies in the desirable range for seismic protection, i.e., 0.05 to 0.15. The analytical investigation reveals that most of these sliding interfaces are effective in reducing spectral accelerations up to 50% and the sliding displacement is restricted within plinth projection of 75 mm (3 in). Green marble and geosynthetic are found to be better alternatives for use in friction isolation system with equal effectiveness of energy dissipation and limiting the earthquake energy transmission to super structure during strong earthquake leading to a low cost, durable solution for earthquake protection of masonry buildings.

Shaking Table Tests of the Smart Restorable Sliding Base Isolation System (SRSBIS)

2011 ◽  
Vol 15 (8) ◽  
pp. 1157-1177 ◽  
Author(s):  
Donatello Cardone ◽  
Peyman Narjabadifam ◽  
Domenico Nigro
Keyword(s):  
Base Isolation ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Isolation System ◽  
Base Isolation System
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