Comparative Study on Nonlinear Earthquake Response of Girder Isolated Bridges with LRB and Model Shaking Table Test

2013 ◽  
Vol 706-708 ◽  
pp. 472-477
Author(s):  
Jie Dong Zhan ◽  
Xin Tong Li ◽  
Yang Li
Keyword(s):  
Seismic Response ◽  
Shaking Table Test ◽  
Experimental Results ◽  
Shaking Table ◽  
Vertical Force ◽  
Isolation System ◽  
Nonlinear Seismic Response ◽  
Girder Bridges ◽  
Deformation Properties ◽  
Rubber Bearings

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.

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.

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.

Parameter Analysis and Shaking Table Test Based on Mechanics Analysis in Seismic Isolation System of Transformer with Bushings

2013 ◽  
Vol 859 ◽  
pp. 33-42
Author(s):  
Mei Gen Cao ◽  
Juan Mo
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Power Transformer ◽  
Shaking Table ◽  
Parameter Analysis ◽  
Particle Analysis ◽  
Isolation System ◽  
Large Power ◽  
Isolation Layer

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.

Benchmark of Elastic Plastic Seismic Response Analysis and Fatigue Evaluation for Piping

2015 ◽  
Author(s):  
Teruyoshi Otoyo ◽  
Akihito Otani
Keyword(s):  
Seismic Response ◽  
Shaking Table Test ◽  
Time History ◽  
Experimental Results ◽  
Shaking Table ◽  
Response Analysis ◽  
Seismic Evaluation ◽  
Seismic Response Analysis ◽  
Elastic Plastic ◽  
Fatigue Evaluation

This paper shows a benchmark result regarding elastic-plastic seismic response analysis and fatigue evaluation for of piping model excitation test. National Research Institute for Earth Science and Disaster Prevention (NIED) has a lot of experimental results of shaking table test of piping. To propose advance seismic evaluation method for piping under severe seismic event, a task in JSME Code committee performs benchmark activity for elastic plastic seismic response analysis and evaluation for piping by using NIED’s experimental results [1]. Authors are taking part in the task and have been performed a benchmark of seismic response analysis and seismic evaluation by comparing with the experimental results. For fatigue evaluation, the strain ranges and the cycles of each range obtained from strain time history were evaluated. The response acceleration and displacement was evaluated for plastic collapse.

scholarly journals Seismic Response of Prestressed Anchors with Frame Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Shuaihua Ye ◽  
Zhuangfu Zhao
Keyword(s):  
Seismic Response ◽  
Shaking Table Test ◽  
Coupling Effect ◽  
Soil Mass ◽  
Calculation Model ◽  
Shaking Table ◽  
Frame Structure ◽  
Dynamic Calculation ◽  
Concentrated Mass ◽  
Linear Spring

Based on the equivalent mass-spring model and considering the coupling effect between creep soil and prestressed anchors, the dynamic calculation model of prestressed anchors with frame structure is established. The soil mass is expressed in the form of concentrated mass. The action of the frame structure on the soil is treated as a parallel coupling of a linear spring and a linear damper, and the free section of the anchor is treated as a linear spring. Considering the creep characteristics, the soil is regarded as a Generalized Kelvin body and the anchoring section of the anchor is regarded as an equivalent spring body, which are coupled in parallel. Considering the effect of slope height, the dynamic calculation model is solved and the seismic response is analyzed. Finally, an engineering example is used to verify the calculation method in this paper, and the results are compared with the shaking table test and numerical simulation. It shows that the calculation model proposed in this paper is safe and reasonable for the seismic design and analysis of the slope supported by prestressed anchors with frame structure.

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.

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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