Aseismic Roof Isolation System Built with Steel Oval Elements: Exploratory Study

2005 ◽  
Vol 21 (1) ◽  
pp. 225-241 ◽  
Author(s):  
Roberto Villaverde ◽  
Manuel Aguirre ◽  
Charles Hamilton

Presented herein are the details of and results from an experimental study conducted to assess the feasibility and effectiveness of a proposed roof isolation system whose purpose is to reduce earthquake damage in buildings. The proposed isolation system entails the detachment of a building's roof from the rest of the building through the insertion of sliding bearings and the attachment of oval-shaped steel elements between the building's roof and the structure below. The objective is to form a simple resonant oscillator with a building's roof and these oval elements, with the roof providing the mass of the oscillator and the oval elements its spring and damper. An additional intention is to make the steel oval elements undergo a large number of inelastic deformation cycles and dissipate, as a result, a large portion of the energy transmitted to a building during an earthquake. The study involves the testing of a small steel frame on a shaking table alternatively with and without the proposed roof isolation system and a comparison of the story drifts and floor accelerations attained in each case. In the conducted tests, the suggested isolation technique effectively reduces the seismic response of the frame. It is concluded, thus, that the proposed roof isolation system has the potential for the development of an inexpensive and effective way to reduce earthquake damage in some buildings and merits further study.

2012 ◽  
Vol 446-449 ◽  
pp. 378-381
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yu Hong Ma ◽  
Chao Yong Shen

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with lead rubber bearing are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.


2010 ◽  
Vol 163-167 ◽  
pp. 4449-4453
Author(s):  
Wei Xiong ◽  
Hing Ho Tsang ◽  
S.H. Lo ◽  
Shou Ping Shang ◽  
Hai Dong Wang ◽  
...  

In this study, an experimental investigation program on a newly proposed seismic isolation technique, namely “Geotechnical Seismic Isolation (GSI) system”, is conducted with an aim of simulating its dynamic performance during earthquakes. The testing procedure is three-fold: (1) A series of cyclic simple shear tests is conducted on the key constituent material of the proposed GSI system, i.e., rubber-sand mixture (RSM) in order to understand its behavior under cyclic loadings. (2) The GSI system is then subjected to a series of shaking table tests with different levels of input ground shakings. (3) By varying the controlling parameters such as percentage of rubber in RSM, thickness of RSM layer, coupled with the weight of superstructure, a comprehensive parametric study is performed. This experimental survey demonstrates the excellent performance of the GSI system for potential seismic hazard mitigation.


Author(s):  
Shigeru Aoki ◽  
Yuji Nakanishi ◽  
Kazutoshi Tominaga ◽  
Takeshi Otaka ◽  
Tadashi Nishimura ◽  
...  

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.


Author(s):  
C. S. Tsai ◽  
Yung-Chang Lin ◽  
Wen-Shin Chen

Seismic mitigation of high-tech facilities is a very important issue in earthquake prone areas such as Taiwan, Japan, U.S.A., etc. In order to lessen vulnerability of earthquake damage of high-tech equipment, base isolation seems to be a good choice. This paper mainly explores the possibility of using a new base isolation system named the trench friction pendulum system (TFPS) to reduce seismic responses of high-tech facilities. The main reasons, from a engineer’s point of view, to use this system for protecting high-tech equipment from earthquake damage are high efficiency and low cost. A series of shaking table tests for a high-tech facility isolated with TFPS isolators were carried out in the Department of Civil Engineering, Feng Chia University, Taichung, Taiwan, ROC. The experimental results show that the proposed system provides a good protection for the high-tech facility during strong earthquakes.


2013 ◽  
Vol 706-708 ◽  
pp. 472-477
Author(s):  
Jie Dong Zhan ◽  
Xin Tong Li ◽  
Yang Li

Abstract: The thesis is aimed to study the characteristics nonlinear seismic response of the isolated continuous girder bridges with LRB. Inorder to achieve the aim, force- deformation properties of the LRB is considered as bilinear first, the bouc-wen model is adopted to imitate the force nonlinear deformation behavior of LRB, and by using Finite element method, the motion equation of the Isolation system of continuous girder bridge is established, then some shaking table tests towards the model of isolated continuous girder bridges with LRB is done. On this basis of it, by comparing the experimental results and calculation results, such as the acceleration and displacement of deck, vertical force of bearing, and the relationship between the Isolation layer displacement and the Level force displacement of the Bearing, we can see that the difference between the analytical results and the experimental results are very small. The results show that the calculation method can analyze Nonlinear Seismic Response of isolated continuous girder bridges with LRB efficiently. But when the vertical earthquake component is larger ,whether the results of the Vertical tension are produced or not, designing the Rubber bearings should be considered.


2012 ◽  
Vol 226-228 ◽  
pp. 1149-1152
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Xiang Yun Huang

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with linear natural rubber bearing and viscous damper are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.


2013 ◽  
Vol 859 ◽  
pp. 33-42
Author(s):  
Mei Gen Cao ◽  
Juan Mo

Earthquake damage many times in history indicate thatthe destroy type of large power transformer is diverse in earthquake andvulnerability is very high. Isolationtechnology can effectively reduce seismic response of the transformer and bushings,but transformer isolation layer design and parameter selection have a largerimpact on the isolation effect. Firstly, one transformer model installing 220,500kV real bushings for testing and analysis is designed which its structural dimension is closer totrue transformer. Multi-particle analysis model of the transformer withbushings isolation system (TBIS)and the equations of motion are established, and calculationprocedures are compiled using MATLABprogram. Secondly, impacts analysis on equivalent horizontal stiffness and dampingratio of the isolation layer are carried out subjectedto earthquake. Reasonable ranges ofstiffness and damping parameters have been determined. Earthquake simulatortesting of the transformer with real bushings is implement which transformertank filled with water in the test. Acceleration, displacement and stressresponse of transformer and bushings with or without isolation bearings wereobtained. Analysis and experiments show that the rational designing isolationlayer parameters can effectively reduce the seismic response of transformers andbushings. In conclusion, mentioned above research have reference role toseismic isolation design and application for power transformer and bushings forthe future.


2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yan Shi ◽  
Zhanhong Zhang ◽  
Hongguo Qin ◽  
Xiangyu Zhao ◽  
Xiong Yang

Based on the seismic isolation design concept of functional separation, a seismic isolation system with bearings and braces combination for railway bridge was proposed. The sliding bearings afford the vertical loads, and the self-centering energy dissipation brace (SCED) and buckling restrained brace (BRB) control the horizontal displacement of the beam, so the functional separation was achieved under the combined action. Taking a long-span railway continuous beam-arch bridge as an example, the corresponding analysis model was established to study lateral seismic response and the girder’s displacement pattern of the continuous beam-arch bridge under the earthquake excitations. The seismic response of bridges with different seismic isolation schemes was studied. The result showed that the presence of arch rib in a continuous beam-arch bridge amplifies the transverse displacement response of the girder compared with that in a continuous beam bridge of equal mass. The seismic isolation system with sliding bearings and energy dissipation braces can control the relative displacement between the pier and beam greatly, and the SCED can reduce or even eliminate the residual displacement between pier and beam. Furthermore, under the strong ground motions, the combined use of SCED and BRB can achieve the seismic isolation to the maximum extent when the self-centering force ratio ζ, the ratio of self-centering force to superstructure weight, is 0.074.


2014 ◽  
Vol 580-583 ◽  
pp. 1490-1493 ◽  
Author(s):  
Wei Xiong ◽  
Ming Ren Yan ◽  
Yao Zhuang Li

The isolation effectiveness of the Geotechnical Seismic Isolation (GSI) system was further investigated via a series of prescribed shaking-table tests. The dynamic response of GSI system was also evaluated in detail of this work. A parametric study for assessment of the isolation performance of GSI was conducted by varying experimental key parameters, such as rubber percentage of rubber-sand mixtures (RSM), configuration of the foundation, storey number of the superstructure, and different kinds of seismic acceleration inputs. From the parametric survey, it can be concluded that the GSI system can to some extent attenuate the dynamic response of the superstructure under big earthquake shakings.


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