scholarly journals Seismic responses of multi-story building isolated by Lead-Rubber Bearings considering effects of the vertical stiffness and buckling behaviors

2021 ◽  
Vol 1030 ◽  
pp. 012080
Author(s):  
Van-Tu Nguyen ◽  
Xuan-Dai Nguyen
Keyword(s):  
Seismic Responses ◽  
Vertical Stiffness ◽  
Lead Rubber Bearings ◽  
Rubber Bearings ◽  
Story Building

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.

scholarly journals An Experimental Study on the Mechanical Properties of a High Damping Rubber Bearing with Low Shape Factor

2021 ◽  
Vol 11 (21) ◽  
pp. 10059
Author(s):  
Zhenyuan Gu ◽  
Yahui Lei ◽  
Wangping Qian ◽  
Ziru Xiang ◽  
Fangzheng Hao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Shape Factor ◽  
Vertical Stiffness ◽  
Rubber Bearing ◽  
High Damping Rubber Bearing ◽  
Lead Rubber Bearings ◽  
Good Energy ◽  
High Damping Rubber ◽  
Rubber Bearings

A high damping rubber bearing (HDRB) is widely utilized in base-isolation structures due to its good energy dissipation capacity and environmentally friendly properties; however, it is incapable of isolating the vertical vibration caused by earthquakes and subways effectively. Thick rubber bearings with a low shape factor have become one of the important vertical isolation forms. This paper provides an experimental comparative study on high damping rubber bearings with low shape factor (HDRB-LSF), thick lead–rubber bearings (TLRB), and lead–rubber bearings (LRB). The abilities of the bearing and energy dissipation of the above bearings are analyzed contrastively considering the influence of vertical pressure, loading frequency, shear strain, and pre-pressure. Firstly, the HDRB-LSF, TLRB, and LRB are designed according to the Chinese Code for seismic design of buildings. Secondly, cyclic vertical compression tests and horizontal shear tests, as well as their correlation tests, are conducted, respectively. The vibrational characteristics and hysteresis feature of these three bearings are critically compared. Thirdly, a corrected calculation of vertical stiffness for the thick rubber bearings is proposed based on the experimental data to provide a more accurate and realistic tool measuring the vertical mechanical properties of rubber bearings. The test results proved that the HDRB-LSF has the most advanced performance of the three bearings. For the fatigue property, the hysteresis curves of the HDRB-LSF along with TLRB are plump both horizontally and vertically, thus providing a good energy dissipation effect. Regarding vertical stiffness, results from different loading cases show that the designed HDRB-LSF possesses a better vertical isolation effect and preferable environmental protection than LRB, a larger bearing capacity, and, similarly, a more environmentally friendly property than TLRB. Hence, it can avoid the unfavorable resonance effect caused by vertical periodic coupling within the structure. All the experimental data find that the proposed corrected equation can calculate the vertical stiffness of bearings with a higher accuracy. This paper presents the results of an analytical, parametric study that aimed to further explore the low shape factor concepts of rubber bearings applied in three-dimensional isolation for building structures.

Implementation and Validation of a Numerical Model for Lead-Rubber Seismic Isolation Bearings

2017 ◽  
Vol 35 (02) ◽  
pp. 153-165 ◽  
Author(s):  
T. Zhou ◽  
Y. F. Wu ◽  
A. Q. Li
Keyword(s):  
Numerical Model ◽  
Seismic Isolation ◽  
Model Simulation ◽  
Lateral Displacement ◽  
Piecewise Linear ◽  
Stability Limit ◽  
Lateral Interaction ◽  
Vertical Stiffness ◽  
Lead Rubber Bearings ◽  
Rubber Bearings

ABSTRACTThis paper presents a numerical model for accurately representing the behaviors of lead-rubber bearings during earthquakes. This model, which is implemented in OpenSees as a user-defined element, accounts for the mechanical characteristics of bearings as follows: firstly, the bi-lateral interaction effect of hysteretic behaviors, as well as the variation in horizontal stiffness due to vertical load, is considered; secondly, the reduced vertical stiffness under large lateral displacement is incorporated by the piecewise linear formulation, and the linear reduction method is employed to determine the stability limit of bearings in the deformed configuration; furthermore, the cavitation and permanent damage effects in bearings are mathematically included. To validate the numerical model, simulation analyses are performed for a series of static and dynamic loading tests, and the numerical results show reasonable agreement with experimental ones, which indicates that the proposed model provides an effective tool for the failure mode analyses of bearings and the dynamic analyses of seismic isolated structures.

Research on the Effect of Combined Seismic Isolation System

2012 ◽  
Vol 446-449 ◽  
pp. 3299-3303
Author(s):  
Xi Sen Fan ◽  
Ting Lei Tian
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Seismic Responses ◽  
Combined System ◽  
Isolation System ◽  
Lead Rubber Bearings ◽  
Base Isolation System ◽  
Rubber Bearings ◽  
The Relationship

The isolation system between the upper structure and the foundation could reduce the seismic response of the former. A system combined of sliding and lead rubber bearings (LRB) is more effective in seismic isolation than using the later alone. In this research, the seismic responses of a building which was set with LRB and a combined system (the proportions between the sliding and LRB were 1/6, 1/4 and 1/3) respectively were analyzed and compared to that of the building without base isolation system to investigate the effect of seismic isolation. The relationship between isolation coefficient and the proportion of bearings was studied. The results show that the combined system could reduce the seismic response of structure, and it is more effective in seismic isolation if the leading bearing is relatively more.

An Investigation of Adaptive Rubber Bearings

2016 ◽  
Author(s):  
C. S. Tsai ◽  
Hui-Chen Su ◽  
Wen-Chun Huang
Keyword(s):  
Yield Strength ◽  
Lower Yield ◽  
Passive Devices ◽  
Major Benefit ◽  
Lead Rubber Bearings ◽  
Lower Yield Strength ◽  
Multiple Levels ◽  
Materials Used ◽  
Rubber Bearings ◽  
Stiffness And Damping

Proposed in this study are several innovative seismic isolators composed of rubber materials that are called adaptive rubber bearings based on their adaptive characteristics. The materials used in the proposed isolators are free of lead commonly found in lead rubber bearings. The lead material results in a heavy environmental burden as well as lower yield strength and damping due to rising temperature during earthquakes, and thus causes larger displacements than we would expect. The designed mechanisms in the proposed isolators enable these devices to be manufactured relatively easily. They also provide extremely high damping to bearings, which is strongly desired by engineers in practice. The proposed rubber bearings are completely passive devices yet possess adaptive stiffness and adaptive high damping. The change in stiffness and damping is predictable and can be calculated at specifiable and controllable displacement amplitudes. The major benefit of the adaptive characteristics of seismic isolators is that a given system can be optimized separately for multiple performance objects at multiple levels of earthquakes. In this study, mathematical formulations are derived to explain the mechanisms of the proposed devices. Experimental results of high velocity cyclical loadings are also provided to verify the advanced concepts of the proposed devices.

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.

Effects of Heating on the Behavior of Lead-Rubber Bearings. I: Theory

2009 ◽  
Vol 135 (12) ◽  
pp. 1440-1449 ◽  
Author(s):  
Ioannis V. Kalpakidis ◽  
Michael C. Constantinou
Keyword(s):  
Lead Rubber Bearings ◽  
Rubber Bearings
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