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.

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.

scholarly journals Seismic Protection of Cabinet Stored Cultural Relics with Silicone Dampers

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Xiaoqing Ning ◽  
Junwu Dai ◽  
Wen Bai ◽  
Yongqiang Yang ◽  
Lulu Zhang
Keyword(s):  
Numerical Simulation ◽  
Seismic Performance ◽  
Shaking Table ◽  
Seismic Protection ◽  
Shaking Table Tests ◽  
Seismic Methods ◽  
Cultural Relics

Cultural relics are precious properties of all humankind, the damage of which is nonresilient. In previous earthquakes, stored cultural relics have shown poor seismic performance, so effective seismic methods are urgently needed. However, due to various restrictions, traditional damping methods are not suitable for the cultural relics stored in the Palace Museum. An efficient damping method, composed of silicone damper and connecting elements, is proposed to protect these stored cultural relics. This novel damping device is very convenient to install and no change or move for the original structures is needed. It is suitable for various kinds of new and existing relic cabinets. In order to validate the effectiveness of this novel damping method, both numerical simulation and shaking table tests are carried out. Results show that this method can effectively enhance the seismic performance of relic cabinet itself and the internal cultural relics. Relic cabinets with damping devices deform significantly less than noncontrol cabinets while the inside relics also have less sliding or overturning. Overall, a damping method, designed for seismic protection of cabinet stored cultural relics, is proposed and its effectiveness has been successfully demonstrated.

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.

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.

AN EXPERIMENTAL STUDY OF IN-PLANE, ARCH-SHAPED FLEXURAL DAMPER

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Yen-Po Wang ◽  
Di-Hung Chen ◽  
Chien-Liang Lee
Keyword(s):  
Experimental Study ◽  
Stress Concentration ◽  
Seismic Performance ◽  
Shaking Table ◽  
Seismic Protection ◽  
Building Structures ◽  
Shaking Table Tests ◽  
Earthquake Intensity ◽  
Component Test ◽  
Portal Frame

An innovative displacement-dependent metallic yielding damper designed to deform inelastically under in-plane flexural bending for seismic protection of building structures is proposed. The in-plane flexural damper that originated from a portal frame is modified by replacing the beam with a circular arch so that the effect of stress concentration can be minimized. Component tests of the in-plane dampers were conducted and compared with analytical results. Hysteresis of the component test indicates a consistent energy-dissipative characteristic of the damper. Moreover, seismic performance of the proposed damper via a series of shaking table tests was carried out. Excellent seismic performance of the proposed in-plane arched damper was observed. The acceleration responses in both peak and root-mean-squares of all floors are significantly reduced, and were greater in extent compared to the earthquake intensity increases.

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.

scholarly journals Dynamic Analysis of a Spring-Asphalt Three-Dimensional Isolation System Based on Cyclic Simple Shear and Shaking Table Tests

2020 ◽  
Vol 10 (18) ◽  
pp. 6530
Author(s):  
Shouping Shang ◽  
Zhen Wang
Keyword(s):  
Simple Shear ◽  
Low Cost ◽  
Three Dimensional ◽  
Least Square Method ◽  
Least Square ◽  
Shaking Table ◽  
Loading Frequency ◽  
Damping Properties ◽  
Shaking Table Tests ◽  
Isolation System

Damping is one of the important issues related to isolated structures, including the newly proposed low-cost spring-asphalt isolation system. In this study, the damping properties of the system in terms of displacement dependence, frequency dependence and temperature dependence were studied by a cyclic simple shear experiment. Then, the direct least-square method was used to identify the damping properties from the experimental data. Furthermore, to validate the effectiveness of the damping device, a modal analysis was conducted based on multi-dimensional shaking table tests. The results indicate that (1) the hysteretic curves are similar to an ellipse, which means that the asphalt shows characteristics of viscoelastic materials; (2) the damping properties are positively related to the loading frequency and inversely related to the temperature and displacement; and (3) asphalt can provide adequate damping and reduce the displacements of the superstructure by nearly half. On the basis of the experimental test results, an analysis of the modal information with multi-dimensional input is also presented.

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 on a Spherical Tank Mock-Up Provided With Seismic Isolation and Flexible Piping Connections

2006 ◽  
Author(s):  
Massimo Forni ◽  
Alessandro Poggianti ◽  
Giulia Bergamo ◽  
Fabrizio Gatti
Keyword(s):  
Seismic Isolation ◽  
Shaking Table ◽  
Seismic Protection ◽  
Piping System ◽  
Fiber Reinforced ◽  
Shaking Table Tests ◽  
Fixed Base ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Rubber Bearings

The Project INDEPTH (Development of INnovative DEvices for Seismic Protection of PeTrocHemical Facilities), supported by the European Commission, has the objective of developing and applying innovative seismic isolation and/or dissipation systems for critical structures at petrochemical facilities. In the framework of INDEPTH, integrated seismic protection systems have been conceived, developed and tested. They are aimed at protecting liquid-filled structures (product storage, spherical and LNG tanks), with new devices (fiber-reinforced isolators, buckling reinforced braces) specific for each application and new flexible piping couplings, to compensate the displacements resulting from the use of isolation systems. The research program has been focused on the selection of critical structures, the design and manufacturing of the devices, the numerical assessment and the experimental validation through shaking table tests [1–4]. A quantification of technical/economical/safety benefits with respect to the conventional state-of-the-art measures presently adopted and potential application to retrofitting has been performed. This paper describes the validation through shaking table tests of the effectiveness of the isolation systems on a spherical mock-up and the related piping system equipped with flexible joints. Different configurations of the mock-up have been tested, such as: fixed base, isolated base with High Damping Rubber Bearings, Fiber Reinforced Rubber Bearings and Lead Rubber Bearings. Furthermore, each configuration has been tested for three different level of filling to verify the sloshing behavior in the sphere and the effectiveness of the isolation systems at filling levels different from the design one (full sphere).

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