scholarly journals Seismic Response Analysis of Fully Base-Isolated Adjacent Buildings with Segregated Foundations

2018 ◽  
Vol 2018 ◽  
pp. 1-21 ◽  
Author(s):  
Khaled Ghaedi ◽  
Zainah Ibrahim ◽  
Mohammed Jameel ◽  
Ahad Javanmardi ◽  
Hamed Khatibi
Keyword(s):  
Base Isolation ◽  
Separation Distance ◽  
Response Analysis ◽  
Seismic Gap ◽  
Base Shear ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Adjacent Buildings ◽  
Construction Methods ◽  
Base Isolation System

In populous cities, construction of multistorey buildings close to each other due to space limitation and increased land cost is a dire need. Such construction methods arise several problems during earthquake excitation. The aim of this study is to investigate the bidirectional seismic responses of fully base-isolated (FBI) adjacent buildings having different heights and segregated foundations. Therefore, two scenarios, namely, (a) investigation of the responses of FBI adjacent buildings compared to those with fixed base (FFB) and (b) the effects of separation distance on FBI adjacent buildings, were studied. Based on these investigations, the results showed that isolation system significantly enhances the overall responses of the BI buildings. Spectacularly, the base isolation system was further efficient to decrease displacement rather than the acceleration. In addition, increase of the seismic gap changed the acceleration, pounding, base shear, base moment, and storey drift, as well as the force-deformation performance of the isolators. Therefore, it seems a need to focus on the effect of the separation distances for the design of base isolators for FBI adjacent buildings in future works.

Seismic Evaluation of Base Isolated System Equipped with Shape Memory Alloys

2013 ◽  
Vol 831 ◽  
pp. 110-114
Author(s):  
S. Alvandi ◽  
M. Ghassemieh
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Seismic Isolation ◽  
Passive Control ◽  
Structural Model ◽  
Base Isolation ◽  
Base Shear ◽  
Seismic Evaluation ◽  
Isolation System ◽  
Base Isolation System

Seismic isolation system is an example of passive control system that effectively improves the performance of structures. This research discusses the seismic performance of a elastomeric base isolation system which provide the combined features of vertical load support, horizontal flexibility and energy absorbing capacity, utilizing shape memory alloys that provides re-centering force and additional damping in the system. Also this paper compares the effect of such alloys with memory effect and/or superelasticity (with pre-straining) in base isolated structure. To provide such comparison, a nonlinear structural model has been developed on some benchmark control problems and some health monitoring evaluation criterias are used. The smart base isolation utilizes the different responses of shape memory alloys at several levels of strain to control the displacements of the rubber bearing and base shear at excitation level. Furthermore the proposed based isolation systems has enhanced performance in terms of response reduction and re-centering capacity.

Seismic base isolation for steel structures

1985 ◽  
Vol 12 (1) ◽  
pp. 73-81
Author(s):  
S. F. Stiemer ◽  
B. B. Barwig
Keyword(s):  
Base Isolation ◽  
Steel Structures ◽  
Experimental Tests ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Experimental Investigations ◽  
Steel Buildings ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Base Isolation System

Base isolation is a strategy for a design of buildings in areas where seismic loads govern. It enables the reduction of earthquake excitation to an acceptable level, without an increase of structural acceleration. This paper presents the results of the experimental investigations of various schemes of first-storey designs for steel buildings with base isolation.A scaled-down steel frame building was used for the shaking table tests, which were conducted in the Earthquake Simulator Laboratory of the University of British Columbia. The base-storey design was altered while the dynamic response of the frame was recorded. The base isolation consisted of steel roller bearings with parallel steel yield rings, to limit excessive displacements and provide wind restraint.The proposed base storey is substantially different from conventional solutions. The variation in the base-storey design was aimed at the elimination of the blind base storey or double foundation in order to increase the economy of the base-isolation system. The experimental tests showed suitable design approaches, and analytical studies to optimize them will follow.It was verified that uncoupling of buildings from the earthquake ground motion is relatively simple to achieve. Certain restraint is required to resist wind and other horizontal loads. This is usually achieved by mechanical fuses or energy absorbers. A solid state energy absorber was used in the described tests. Key words: base-isolation system for buildings, earthquake-resistant steel structures, experimental investigations, retrofit system.

Seismic Analysis of Base-Isolated San Bernardino County Building

1992 ◽  
Vol 8 (4) ◽  
pp. 605-633 ◽  
Author(s):  
Bruce F. Maison ◽  
Carlos E. Ventura
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Seismic Gap ◽  
Elastic Model ◽  
San Bernardino County ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Soft Story ◽  
Linear Elastic ◽  
Linear Elastic Model

The authors investigate the seismic behavior of an existing base isolated building and interpret its recorded response to the 1990 Upland California earthquake. They formulate a linear-elastic model that accurately represents the building during the earthquake and infer its response behaviors. Additional analyses using severe earthquake excitations demonstrate the building behavior in major events and hypothetical seismic gap pounding situations. Key findings include the following: • The Upland earthquake resulted in relatively low intensity shaking at the site, and the building did not exhibit a classic soft story effect in the isolation system. • A linear-elastic model can accurately idealize the building during this event. • Under major earthquake excitation, base isolation can lead to peak story drifts, shears, overturning moments, and accelerations that are much smaller than those of nonisolated buildings. • Pounding at seismic gaps can produce large story drifts, shears and accelerations. These peak pounding responses can be greater than those from nonisolated buildings (i.e., having no pounding).

Optimization of Second Isolation Period for Parallel Base-Isolated System

2012 ◽  
Vol 256-259 ◽  
pp. 1117-1120
Author(s):  
Q. Rong
Keyword(s):  
Objective Function ◽  
Seismic Response ◽  
Base Isolation ◽  
Energy Scale ◽  
Base Shear ◽  
Isolation System ◽  
Base Isolation System ◽  
Low Amplitude ◽  
Variation Rule ◽  
Isolation Period

The optimization of second isolation period for parallel base isolation system is investigated systematically. The maximum dissipative energy scale factor is used as the objective function, the maximum sliding displacement of base-isolated layer, the residual displacement and the maximum base shear coefficient are considered as the constraining factors. For first to fourth category site, under the low amplitude severe earthquake, the variation rule of the four seismic response indicators for the second isolation period is approximately same, the second isolation period is proposed to be in the range of 4s to 6s.

scholarly journals Seismic Performances of Conventional and LRB-Isolated Buildings Comparing to Seesaw Buildings

2020 ◽  
Vol 10 (1) ◽  
pp. 45-54
Author(s):  
Soroush Kherad ◽  
Mahmood Hosseini ◽  
Mehrtash Motamedi
Keyword(s):  
Base Isolation ◽  
Low Cost ◽  
Time History ◽  
Building Structure ◽  
Base Shear ◽  
Isolation System ◽  
Repair Work ◽  
Story Drift ◽  
Base Isolation System ◽  
Nonlinear Time History

AbstractUsing seesaw structural system equipped with energy dissipating devices has been considered as a low-cost and low-tech way for creation of earthquake-resilient buildings. In this paper by considering three groups of multi-story buildings, including conventional buildings, LRB-based isolated buildings and building with seesaw structure, equipped with a newly introduced type of structural fuses, their seismic performances have been compared through nonlinear time history analyses (NLTHA). The employed fuses in seesaw buildings are a specific type of yielding plate dampers, called Multiple Curved Yielding Plate Energy Dissipater (MCYPED), installed at the bottom of the all circumferential columns of the lowest story of the building. To show the efficiency of the proposed seesaw system in comparison with other two mentioned groups, first, by finite element modeling, verified by experimental results, the initial and secondary stiffness values as well as the yielding and ultimate strengths of the MCYPEDs have been obtained to be modeled by multi-linear plastic springs in the seesaw buildings. Then, a series of NLTHA have been performed on the three groups of buildings by using a set of selected earthquakes. The compared responses include roof displacement and acceleration, base shear, inter-story drift and finally plastic hinges (PHs) formed in the building’s structures. Results show that the proposed seesaw building equipped with MCYPEDs not only results in lower seismic demand, similar to base isolation system, but also leads to remarkable energy dissipation capacity in the building structure at base level, so that the building structure remains basically elastic, and does not need any major repair work, even after large earthquakes, contrary to the conventional building which need to be demolished after the earthquake.

scholarly journals Seismic Vibration Control of Building with Lead Rubber Bearing Isolator

10.29007/pvzx ◽  
2018 ◽  
Author(s):  
Kishan Bhojani ◽  
Vishal Patel ◽  
Snehal Mevada
Keyword(s):  
Seismic Response ◽  
Base Isolation ◽  
Time History ◽  
Dynamic Parameter ◽  
Base Shear ◽  
Maximum Displacement ◽  
Maximum Acceleration ◽  
Isolation System ◽  
Loma Prieta Earthquake ◽  
Base Isolation System

During the life span of structure there may be an effect of vibration. Due to vibration there may be major or minor damage in building. Base isolation is best method to reduce the seismic response of the structure. This paper gives idea about base isolation system which can be used in multi-story building to reduce seismic response of the structure. This paper represents the initialize study of dynamic parameter like effective damping for four earthquake time history. In this paper the optimum effective damping has been found out under the effect of Loma Prieta earthquake time history. The parametric study has been conducted to evaluate the effect on maximum displacement, maximum acceleration, maximum base shear in bare frame and frame with isolator.

Nonlinear Seismic Response Analysis of Parallel Base-Isolated System

2012 ◽  
Vol 256-259 ◽  
pp. 2254-2257
Author(s):  
Q. Rong
Keyword(s):  
Base Isolation ◽  
Time History ◽  
Treatment Method ◽  
Response Analysis ◽  
Hysteretic Model ◽  
Isolation System ◽  
Nonlinear Seismic Response ◽  
History Analysis ◽  
Base Isolation System ◽  
Single Mass

Based on the bilinear hysteretic model, the elastic-plastic time history analysis of single mass point for parallel base isolation system is carried out. The approximate treatment method of the inflexion point is introduced and the formula of each energy consumption for parallel base-isolated structure is given. Through an engineering example, the time history curve of each energy dissipation for parallel base-isolated system is drawn, and the isolation effect is given.

scholarly journals Analysis of a Frame-Shear Wall Concrete Structure by Using Base Isolation and Evaluation of Structure-Soil Interaction

2017 ◽  
Vol 7 (6) ◽  
pp. 2282-2287
Author(s):  
H. I. Polat
Keyword(s):  
Cross Sections ◽  
Base Isolation ◽  
Shear Wall ◽  
Structure Design ◽  
Mode Shapes ◽  
Earthquake Response ◽  
Response Analysis ◽  
Seismic Load ◽  
Isolation System ◽  
Base Isolation System

A base isolation system is a type of earthquake-resistant structure design approach based on the principle of reducing a structure’s earthquake response rather than increasing the structure’s earthquake resistance capacity. Seismic base isolated structures have the ability to make large displacements relative to the level of insulation elements. This means that a large structure performs very small displacements between floors during an earthquake and exhibits a rigid body behavior. At this point, the earthquake forces acting on the structure decrease along with the floors. In this article a school building composed of frame-shear wall is resolved primarily with the traditional fixed base structure system, mode shapes are found and periods are obtained. For earthquake response analysis, earthquake loads are distributed to the floors using the equivalent seismic load method and structural elements experiencing capacity problems are found. Then, using the earthquake record, larger failure of cross sections and capacity problems are obtained compared to the first method. In the second stage, the same structure is dissolved again by placing the lead core rubber base isolators between the base and the vertical structural members. The periods of structures under earthquake load have increased significantly by utilizing base isolation, as a result of that spectral accelerations decreased. Thus, large decreases in the shear forces acting to the structure are determined and failures of cross sections are removed.

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