• 제목/요약/키워드: Seismic retrofitted

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Analytical Study on the Seismic Retrofit Method of Irregular Piloti Building Using Knee-Brace (Knee - Brace를 활용한 비정형 필로티 건물의 내진보강방안에 대한 해석적 연구)

  • Yoo, Suk-Hyung;Kim, Dal-Gee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.1
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    • pp.35-42
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    • 2020
  • Torsional behavior due to the plane irregularities of the piloti building can cause excessive story drift in the torsionally outermost column, which can lead to shear failure of the column. As a seismic retrofit method that can control the torsional behavior of the piloti building, the expansion of RC wall, steel frame or steel brace may be used, but such methods may hinder the openness of the piloti floor. Therefore, in this study, linear dynamic analysis and nonlinear static analysis for piloti buildings retrofitted by knee brace were performed, and seismic performance evaluation and torsion control effect of knee brace were analyzed. The results showed that the shear force of the column increased when the piloti building retrofitted by knee brace, but it was effective in controlling the torsional deformation. In case of retrofit between knee brace and column by 30°, the shear force of the column increased less than that of 60°, and the lateral displacement of column was decreased in the order of □, ◯ and H in cross-section.

Quasi-Static Test for Seismic Performance of Circular R.C. Bridge Piers Before and After Retrofitting (유리섬유 보강 원형 철근콘크리트 교각의 내진성능에 관한 준정적 실험연구)

  • 정영수;이강균;한기훈;이대형
    • Journal of the Korea Concrete Institute
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    • v.11 no.5
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    • pp.107-118
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    • 1999
  • 10 RC bridge piers have been made on a 1/3.4 scale model, and six piers of them were retrofitted with glassfiber. The have been tested in the quasi-static cyclic load so as to investigate their seismic enhancement before and after retrofitting with glassfibers. The objective of this experimental study is to investigate how to strength the ductility of reinforced concrete bridge piers which have been nonseismically designed and constructed in Korea before 1992. Important test parameters are axial load, load pattern, retrofit type. Glassfiber sheets were used for retrofitting in the plastic hinge region of concrete piers. The nonlinear behavior of bridge columns have been evaluated through their yield and ultimate strength, energy dissipation, displacement ductility and load-deflection characteristics under quasi-static cyclic loads. It can be concluded from the test that concrete piers strengthened with glassfibers have been enhanced for their ductile behavior by approximate 50%.

Seismic performance evaluation and retrofitting with viscous fluid dampers of an existing bridge in Istanbul

  • Bayramoglu, Guliz;Ozgen, Alpay;Altinok, Enver
    • Structural Engineering and Mechanics
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    • v.49 no.4
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    • pp.463-477
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    • 2014
  • In this paper, seismic performance of Kozyatagi Bridge is evaluated by employing nonlinear elasto-plastic dynamic analysis and the deformation-based performance. The time-history records of the 1999 Izmit, 1971 San Fernando and 1989 Loma Prieta earthquakes are modified by adopting a probability of exceedance of 2% in 50 years corresponding to the return period of 2475 years. The analysis is carried out for three different bearing cases which are movable bearings, restrained bearings, and movable bearings with viscous fluid dampers in the radial direction. The analysis results show that the bridge can be retrofitted with viscous fluid dampers. In this case the reinforced concrete piers need not be strengthened by any jacketing techniques in order to preserve the original architectural appearance of the bridge. The retrofitting design of the bridge with viscous fluid dampers is also presented in detail.

Dynamic Behavior of the Bridge Retrofitted by Restrainer under Seismic Excitations (Restrainer로 보강된 교량의 지진하중에 대한 거동특성분석)

  • 김상효;마호성;이상우;원정훈
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.04a
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    • pp.177-186
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    • 1999
  • Dynamic Characteristics of the bridge motions under seismic excitations are analyzed by adopting multi degree - of - freedom system to estimate the effect of restrainers. The applied restrainer is assumed to be a dead - band - system, which has the force clearance and the linear elastic force. The inelastic behaviors of pier and foundation motions are also considered in the study. It is found that the major effect of restrainer is to remarkably decrease the relative displacement between adjacent girders. It is found that restrainers placed on the parts of the bridge system rather than the whole system may increase the unseating failure.

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Experimental Research for Seismic Performance of Circular Hollow R.C. Bridge Pier (원형중공 콘크리트 교각의 내진성능에 대한 실험적 연구)

  • 한기훈;이강균;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.671-676
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    • 1999
  • Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers, circular hollow columns are widely used in Korean highway bridges. Since the occurrence of 1995 Kobe earthquake, there have been much concerns about seismic design for various infrastructures, inclusive of bridge structures. It is, however, understood that there are not much research works for nonlinear behavior of circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is investigate nonlinear behavior of circular hollow reinforced concrete bridge piers under the quasi-static cyclic load, and then to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It is concluded from quasi-static tests for 7 bridge piers that energy dissipation capacity and curvatures for a given displacement ductility factor $\{\mu}=frac{\Delta}{\Delta_y}$are about 20% higher for the seismically designed columns and about 70% higher for the retrofitted piers than the nonseismically designed columns in a conventional way.

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Circumferential Confinement Effect on Lap-Spliced Reinforcements of Circular Bridge Pier (횡방향 구속이 교각의 겹침이음에 미치는 영향에 대한 고찰)

  • 최영민;황윤국;권태규;박경훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.339-342
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    • 2003
  • The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to deterioration of the lap-spliced longitudinal reinforcements without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by quasi-static experiments.

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Pseudo Dynamic Test for the Seismic Performance Evaluation of Circular RC Bridge Piers Retrofitted with Fibers (섬유보강 원형 RC교각의 내진성능 평가를 위한 유사동적실험)

  • 정영수;박종협;박희상
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.2
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    • pp.49-57
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    • 2001
  • 본 연구의 목적은 유사동적실험에 의한 섬유보강 원형 RC교각의 내진성능평가를 위한 연구로서 수원시에 위치한 내진교량인 하길교를 대상모델로 하였으며, 도로교 표준시방서의 내진설계규정이 적용되지 않은 비내진교각시험체 2본 및 내진성능향상을 위한 섬유보강시험 4본, 즉 총 6본에 대하여 유사동적실험을 수행하였다. 보강공법으로는 유리 탄소섬유 보강공법을 사용하였으며, 실험변수로는 입력지진동, 섬유고방유무로 하였다. 그리고 내진성능평가 방법은 입력 및 소산에너지, 변위 연성도가 분석되었다. 본 실험의 결과 유리 섬유로 보강된 비내진시험체의 변위연성도 KHC인공지진파에 대하여 7.7~9.0정도의 값으로 충분한 내진성능을 확보하고 있는 것으로 평가되었다.

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Circumferential Confinement Effect of Circular Bridge Pier with FRP Wrapping in Earthquake (지진발생시 FRP 보강이 횡방향 구속에 미치는 효과)

  • 최영민;황윤국;권태규;윤순종
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.09a
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    • pp.280-287
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    • 2003
  • The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP laminated circular tube showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by Quasi-static experiments.

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The Pseudo-Dynamic Test for the Seismic Retrofit System Utilizing Existing Bridge Bearings (교량의 기존 받침을 활용하는 내진보강시스템의 유사동적 실험)

  • Kwahk, Im-Jong;Cho, Chang-Beck;Kim, Young-Jin;Kwark, Jong-Won
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.1 s.53
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    • pp.21-27
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    • 2007
  • In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they Just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and lead rubber bearings far the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.

Development of Performance-Based Seismic Design of RC Column Using FRP Jacket by Displacement Coefficient Method (FRP 보강 철근콘크리트기둥의 변위계수법에 의한 내진성능설계기법 개발)

  • Cho, Chang-Geun;Ha, Gee-Joo;Bae, Su-Ho
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.491-497
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    • 2007
  • In the current research, the scheme of displacement-based seismic design for seismic retrofit of concrete structures using FRP composite materials has been proposed. An algorithm of the nonlinear flexural analysis of FRP composite concrete members has been presented under multiaxial constitutive laws of concrete and composite materials. An algorithm for performance-based seismic retrofit design of reinforced concrete columns with FRP jacket has been newly introduced to modify the displacement coefficient method used in reinforced concrete structures. From applications of retrofit design, the method are easy to apply in the practice of retrofit design and give practical prediction of nonlinear seismic performance evaluation of retrofitted structures.