Experimental Investigation on Mid-Story Isolated Structures

2010 ◽  
Vol 163-167 ◽  
pp. 4014-4021
Author(s):  
Xiang Yun Huang ◽  
Fu Lin Zhou ◽  
She Liang Wang ◽  
Liu Han Wen Heisha ◽  
Xue Hai Luo
Keyword(s):  
Dynamic Characteristics ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Seismic Responses ◽  
Isolation Technique ◽  
Vertical Stiffness ◽  
Isolation Layer ◽  
Rubber Bearings

Isolation technique has been acceded as a part of the China Seismic Code for Design of Buildings. In this code, the limitations for using isolation design are very strict, superstructure must be regular and the isolation layer must be located on the top of base (base isolated structure). Because of the needs of architecture and function or the feasibility of technique, some limitations have been broken in recent projects. Sometimes isolated layer can be set on the intermediate story, so-called the mid-story isolated structure. According to the characteristic of structure, isolation layer of mid-story isolated structure is set on a place where the structure’s vertical stiffness is suddenly changed, as like the top of the first story, middle story, conversion story of the structure. Laminated rubber bearings (LRB) are adopted as an isolation layer. Because the isolation layer is set on intermediate story, the whole structure is divided into superstructure and substructure; the structure’s dynamic characteristics are changed. The mechanism of mid-story isolated structure appears different characteristic compared with base isolation. The aim of mid-story isolation is not only to reduce seismic responses of superstructure, but also to reduce seismic responses of the substructure. Theoretical analysis and the shaking table test of the mid-story isolated structure were carried. And the response of mid-story isolated structure is discussed by comparing with the response of base-isolated structure and base fixed structure. The key problems of mid-story isolated structure are the force condition and the interaction of the structure up and below the isolation layer. Many factors, such as the number of story, mass, stiffness of superstructure and substructure, parameter of the isolation layer, have influence on the seismic behavior of the mid-story isolated structure. The optimum combination relationship of these factors is presented and dynamic characteristics and dynamic responses are investigated.

Shaking Table Test Study on Mid-Story Isolation Structures

2012 ◽  
Vol 446-449 ◽  
pp. 378-381
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yu Hong Ma ◽  
Chao Yong Shen
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Natural Period ◽  
Isolation System ◽  
Isolation Layer ◽  
Lead Rubber Bearing ◽  
Complex Structural

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.

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.

Shaking Table Test Study on Mid-Story Isolation Structures with Viscous Damper

2012 ◽  
Vol 226-228 ◽  
pp. 1149-1152
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Xiang Yun Huang
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Viscous Damper ◽  
Natural Period ◽  
Isolation System ◽  
Isolation Layer ◽  
Complex Structural

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.

Dynamic Response Analysis of MSCSS Constructed with Rubber Vibration Isolator

2014 ◽  
Vol 574 ◽  
pp. 179-183
Author(s):  
Tao Li
Keyword(s):  
Base Isolation ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Vibration Isolator ◽  
Seismic Responses ◽  
Earthquake Excitation ◽  
Isolation Technique ◽  
Probability Density Evolution Method ◽  
And Control ◽  
Probability Density Evolution

The seismic responses of the mega-sub controlled structural system (MSCSS) can be reduced effectively based on the combination of the construction and control theory. One of the main construction features of the MSCSS is the connection between the additional column and the mega beam. The rubber vibration isolator is proposed as a new connection mode between the above two components according to the base isolation technique. The dynamic responses of the MSCSS subjected to the earthquake excitation are investigated by employing the probability density evolution method. The analysis results are compared with the seismic responses of the MSCSS constructed with other connection modes. The results show that the seismic responses of the MSCSS constructed with rubber vibration isolator can be reduced effectively, but the effect is not better than the other connection modes.

Experimental Study on Vertical Base-Isolated System with Disk Spring

2012 ◽  
Vol 166-169 ◽  
pp. 788-792
Author(s):  
Yamin Zhao ◽  
Jingyu Su ◽  
Ming Lu
Keyword(s):  
Shaking Table ◽  
Base System ◽  
Performance Tests ◽  
Shaking Table Tests ◽  
Seismic Responses ◽  
Vertical Stiffness ◽  
Disk Spring ◽  
Fixed Base ◽  
Structural Responses ◽  
Vertical Base

A new vertical isolator designed by disk spring, called combined disk spring bearing (DSB), is introduced in this paper. DSB is composed of one main disk spring bearing and eight secondary disk spring bearings. Performance tests show that DSB had good property of variable vertical stiffness and high vertical damping. Then, the effectiveness of DSB vertical base-isolated devices in reducing structural responses caused by earthquakes through a series of 1/2 scale shaking table tests. are conducted to study the seismic responses of the and the DSB vertical-isolated system. Compared with the fixed-base system, experimental results show that the DSB vertical-isolated system can isolate vertical earthquake energy remarkably. Large displacement of the DSB vertical-isolated system occurred on the isolation layer, and the inter-story deformation of the superstructure changed slightly. The acceleration responses of DSB vertical-isolated system decreased more than 50% and the displacement responses decreased more than 40% at 0.4g PGA, which confirmed that DSB could decrease the seismic responses effectively.

Shaking Table Test Study of Reinforced Concrete Shear Wall Structure

2017 ◽  
Vol 865 ◽  
pp. 306-312
Author(s):  
Zheng Li ◽  
Heng Zhou ◽  
Li Qin
Keyword(s):  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
Shaking Table Test ◽  
Time History ◽  
Shear Wall ◽  
Shaking Table ◽  
Wall Structure ◽  
Model Structure ◽  
Fixed Base ◽  
Time History Response

A reduced-scale model of 7-story reinforced concrete shear wall structure is made. Shaking-table test of the model is carried out. Two test conditions are considered. In the first condition, fixed base is used. In another condition, soil structure interaction is considered. According to the experimental results, the dynamic characteristic and seismic performance of shear wall structure is studied. The acceleration time history response of model structure is obtained. Based on the time-history response, the dynamic characteristics of model structure are studied by spectrum analysis. The Finite Element Model of actural structure is established by ANSYS. The dynamic characteristics and seismic performance of actural structure are studied. By comparing the experiment results and numerical analysis results under the fixed-base condition, the rationality of the ANSYS model and numerical analysis method of are verified.

Study on Seismic Isolation and Hi-Frequency Vibration Isolation Technology for Equipment in Nuclear Power Plant Using Aero Floating Technique

2020 ◽  
Author(s):  
Kiyotaka Takito ◽  
Osamu Furuya ◽  
Hiroshi Kurabayashi ◽  
Kunio Sanpei
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Vibration Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Ground Surface ◽  
Shaking Table ◽  
Maximum Acceleration ◽  
Seismic Motion ◽  
Floating Base

Abstract In Japan, most structures on the ground surface need seismic countermeasures because of frequently earthquakes. On the other hand, vibration isolation devices are applied to precision or important equipment in several facilities that dislikes vibration in order to reduce daily vibration. In general, vibration isolation devices are intended for high frequency and small amplitude range. However, it is difficult to cut off both vibration region caused by flying object collision and seismic motion with existing technologies. The authors propose insulation of equipment and vibration transmitted through the floor by floating equipment, and have. We have devised and built an air floating device that operates when a trigger input is applied to save the energy of this dynamically acting device. It was estimated by numerical calculation that the aero floating device keeps lifting stably in the condition with the air pressure in the auxiliary air chamber about 75 to 80 kPa. The performance specifications of the proposed device were verified from shaking table test. As a result, the effect of reducing the maximum acceleration by about 1/5 against the seismic motion of El Centro NS, Taft NS, Tohoku NS, and Hachinohe EW was confirmed by floating the mass on the frame assuming the equipment. From the obtained power spectrum diagram (PSD) of the response acceleration, it was confirmed that all frequency components up to 25 Hz is reduced by using proposed aero floating base isolation device.

Shaking table test of seismic responses of anchor cable and lattice beam reinforced slope

2020 ◽  
Vol 17 (5) ◽  
pp. 1251-1268
Author(s):  
Jian-jing Zhang ◽  
Jia-yong Niu ◽  
Xiao Fu ◽  
Li-cong Cao ◽  
Qiang Xie
Keyword(s):  
Shaking Table Test ◽  
Shaking Table ◽  
Seismic Responses ◽  
Reinforced Slope ◽  
Anchor Cable ◽  
Lattice Beam

scholarly journals Experimental Investigation on Semi-Active Control of Base Isolation System Using Magnetorheological Dampers for Concrete Frame Structure

2019 ◽  
Vol 9 (18) ◽  
pp. 3866 ◽  
Author(s):  
Weiqing Fu ◽  
Chunwei Zhang ◽  
Mao Li ◽  
Cunkun Duan
Keyword(s):  
Optimal Control ◽  
Control System ◽  
Active Control ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Mr Damper ◽  
Shaking Table ◽  
Engineering Practice ◽  
Isolation System ◽  
Large Earthquakes

The traditional passive base isolation is the most widely used method in the engineering practice for structural control, however, it has the shortcoming that the optimal control frequency band is significantly limited and narrow. For the seismic isolation system designed specifically for large earthquakes, the structural acceleration response may be enlarged under small earthquakes. If the design requirements under small earthquakes are satisfied, the deformation in the isolation layer may become too large to be accepted. Occasionally, it may be destroyed under large earthquakes. In the isolation control system combined with rubber bearing and magnetorheological (MR) damper, the MR damper can provide instantaneous variable damping force to effectively control the structural response at different input magnitudes. In this paper, the control effect of semi-active control and quasi-passive control for the isolation control system is verified by the shaking table test. In regard to semi-active control, the linear quadratic regulator (LQR) classical linear optimal control algorithm by continuous control and switch control strategies are used to control the structural vibration response. Numerical simulation analysis and shaking table test results indicate that isolation control system can effectively overcome the shortcoming due to narrow optimum control band of the passive isolation system, and thus to provide optimal control for different seismic excitations in a wider frequency range. It shows that, even under super large earthquakes, the structure still exhibits the ability to maintain overall stability performance.

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