• Earthquakes and Structures
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• 제1권2호
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• pp.215-230
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• 2010

The main objectives of this work were to investigate the effects of the nonlinear behavior of the isolation pads on the seismic response of bridges with rubber bearings, and to identify when base isolation improved their seismic performance. To achieve these objectives a parametric study was conducted designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (accelerations, displacements and pier seismic forces) were evaluated for three different structural models subjected to three earthquakes with different dynamic characteristics. The first represented bridges without base isolation; the second corresponded to the same bridges including now rubber bearings as an isolation system, with linear elastic behavior that shifted the natural period of the bridge by a factor of 2 to 4. In the third model the seismic response of bridges supported on lead-Rubber bearings was studied accounting for the nonlinear behavior of the lead. The results show clearly the importance of the nonlinear behavior on the seismic performance of the bridges.

• Structural Engineering and Mechanics
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• 제40권3호
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• pp.315-334
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• 2011

Seismic isolated building structures are examined in this study. The triple concave friction pendulum (TCFP) is used as a seismic isolation system which is easy to be manufactured and enduring more than traditional seismic isolation systems. In the TCFP, take advantage of weight which pendulum carrying and it's geometry in order to obtain desirable result of seismic isolation systems. These systems offer advantage to buildings which subject to severe earthquake. This is result of damping force of earthquake by means of their internal constructions, which consists of multiple surfaces. As the combinations of surfaces upon which sliding is occurring change, the stiffness and effective friction change accordingly. Additionally, the mentioned the TCFP is modeled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. A two dimensional- and eight- story of a building with and without isolation system are used in the time history analysis in order to investigate of the effectiveness of the seismic isolation systems on the buildings. Results are compared with each other to emphasize efficiency of the TCFP as a seismic isolation device against the other friction type isolation system like single and double concave surfaces. The values of the acceleration, floor displacement and isolator displacement obtained from the results by using different types of the isolation bearings are compared each other. As a result, the findings show that the TCFP bearings are more effective devices for isolation of the buildings against severe earthquakes.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.161-168
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• 1999

The concept of seismic design was induced in our country which was poor in it for the scarcity of recognition and insufficiency of funds. Recently many specialists are enforcing the provisions of seismic design. But because seismic force of seismic design is very great and all the seismic force are concentrated on the fixed bearings and substructure the bearings are the seismic force are concentrated on the fixed bearings and substructure the bearings are destroyed so that seismic design lose its basic concept. In addition when the earthquake which exceeds seismic design force takes place the bridge is collapsed. For these reasons the developed seismic isolation design concept was appeared which diminishes seismic force itself by period shift and additional damping distributes it to each superstructures evenly. Therefore this study introduced the method which combines PC-LEADeR(design program for L.R.B) with SAP 2000(linear elastic analysis) and performs the seismic isolation design more elaborately and simply verified the propriety of that method and examined the force control of L. R. B.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1126-1131
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• 2010

Experimental studies for the high damping rubber bearing, lead rubber bearing and natural rubber bearing, those are often used to improve the seismic capacity if the structure recently, are conducted to evaluate the seismic capacity of the seismic isolation bearings. The shear stiffness of the bearings decrease and the shear strain amplitude or the constant axial load level increase, but not sensitive to the strain rate effect. Bearings are strong for the axial compression but weak for the axial tension.

• Earthquakes and Structures
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• 제10권4호
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• pp.829-847
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• 2016

Generally seismic isolation is achieved by supporting the structure on laminated rubber bearings, friction pendulum bearings, roller bearings etc. Very little work has been performed using soil as a base isolation media. Experiments and analytical work has been performed on a structural model with isolated footing and found encouraging results. Details of this work are presented in this paper.

• Structural Engineering and Mechanics
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• 제54권3호
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• pp.475-489
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• 2015

This study presents the validation of a numerical model developed for dynamic analysis of buildings with roller seismic isolation bearings. Experimental methods allowed validation of the motion equations of a physical model of a building with and without roller bearings under base excitation. The results are presented in terms of modal parameters, frequency response functions (FRFs) and acceleration response. The agreement between numerical and experimental results proves the accuracy of the developed numerical model. Finally, the performance of the constructed seismic protection system is assessed through a parametric study.

• 콘크리트학회논문집
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• 제12권4호
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• pp.79-89
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• 2000

In this paper, the seismic analysis and the modeling techniques have been introduced for aseismic performances assessment, when seismic isolation bearings are applied on a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. In this study, EI Centro earthquake(1940, N00W), Mexico earthquake(1985, N90W), and earthquake simulation from modified SIMQKE are used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.

• Computers and Concrete
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• 제8권6호
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• pp.693-715
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• 2011

The main object of this study is to evaluate the seismic response effects on a reinforced concrete building isolated by triple concave friction pendulum (TCFP) bearings. The site-response effects arise from the difference in the local soil conditions at the support points of the buildings. The local soil conditions are, therefore, considered as soft, medium and firm; separately. The results on the responses of the isolated building are compared with those of the non-isolated. The building model used in the time history analysis, which is a two-dimensional and eight-storey reinforced concrete building with and without the seismic isolation bearings and/or the local soil conditions, is composed of two-dimensional moment resisting frames for superstructure and of plane elements featuring plane-stress for substructure. The TCFP bearings for isolating the building are modelled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. In order to investigate the efficiency of both the seismic isolation bearings and the site-response effects on the buildings, the time history analyses are elaborately conducted. It is noted that the site-response effects are important for the isolated building constructed on soft, medium or firm type local foundation soil. The results of the analysis demonstrate that the site-response has significant effects on the response values of the structure-seismic isolation-foundation soil system.

• Smart Structures and Systems
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• 제2권4호
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• pp.329-337
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• 2006

This paper illustrates an analytical investigation of the vibration parameters of buildings on sliding seismic isolation bearings with elastic limiters of the relative displacement. The installation scheme of sliding bearings and elastic limiters for the separate unit of a 4 storey hospital building with brick walls is designed. The analysis of the vibrations of the hospital building is conducted for harmonic base excitation.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.415-423
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• 2000

In this study, a computer program was developed for the seismic response analysis of the structures with base isolation bearings. On a 6-story steel frame structure isolated by lead rubber bearings and friction pendulum bearings, seismic response analyses using the developed program and commercial program and experiments were carried out. The results were compared one another and discussed.