• Title, Summary, Keyword: 준 정적 실험

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Performance Assessment of Hollow Precast Segmental PSC Bridge Columns (중공 프리캐스트 세그먼트 PSC 교각의 성능평가)

  • Kim, Tae-Hoon;Park, Young-Ky;Kim, Young-Jin;Shin, Hyun-Mock
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.1
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    • pp.51-62
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    • 2010
  • The purpose of this study was to investigate the performance of hollow precast segmental PSC bridge columns. The proposed system can reduce work at a construction site and makes construction periods shorter. Shortened construction times, in turn, lead to important safety and economic advantages when traffic disruption or rerouting is necessary. Two hollow precast segmental PSC bridge columns were tested under a constant axial load and a quasistatic, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures, was used. The proposed numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated.

Detecting Java Class Theft using Static API Trace Birthmark (정적 API 트레이스 버스마크를 이용한 자바 클래스 도용 탐지)

  • Park, Hee-Wan;Choi, Seok-Woo;Lim, Hyun-Il;Han, Tai-Sook
    • Journal of KIISE:Computing Practices and Letters
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    • v.14 no.9
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    • pp.911-915
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    • 2008
  • Software birthmark is the inherent characteristics that can identify a program. In this paper, we propose a Java class theft detection technique based on static API traces of class files. We utilize control flow analysis to increase resilience, and we apply the semi-global alignment trace comparison algorithm to increase credibility. The credibility and resilience experiments for XML parsers show that our birthmark is more efficient than existing birthmarks.

Seismic Performance Evaluation of SRC Column by Quasi-Static Test (준정적 실험에 의한 SRC 합성교각의 내진성능 평가)

  • Han, Jung-Hoon;Park, Chang-Kyu;Shim, Chang-Su;Chung, Young-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.4
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    • pp.85-94
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    • 2006
  • In the design of bridge piers in seismic area, the ductility requirement is the most important factor. In order to enhance the seismic performance of RC columns, it is necessary to make the ductility of columns larger by covering RC columns with steel tubes or confining RC columns by arranging transverse reinforcements such as hoop ties closely. Using core steel composite columns is useful as one of the reinforcing RC columns. In this paper, quasi-static tests on concrete encased composite columns with single core steel or multiple steel elements were performed to investigate the seismic performance of the composite columns. Eight concrete-encased composite specimens were fabricated. The cross-sections of these specimens are composed of concrete-encased H-shaped structural steel columns and a concrete-encased circular tube with partial in-filled concrete. Test parameters were the amount of the transverse reinforcements, type and number of encased steel member. Through the tests, it was evaluated the ductility of SRC composite specimens. It has become clear from the test results that encased steel elements makes the deformation capacity of the columns to be larger. The displacement ductility and lateral strength of specimen with concrete-encased circular tube were indicated the biggest value.

An Experimental Study on Seismic Performance of Precast Segmental PSC Bridge Piers with Precast Footings (프리캐스트 기초부를 갖는 조립식 PSC 교각의 내진성능에 관한 실험적 연구)

  • Kim, Tae-Hoon;Park, Se-Jin;Kim, Young-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.451-452
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    • 2009
  • The purpose of this study was to investigate the seismic performance of precast segmental PSC bridge piers with precast footings. A model of precast segmental PSC bridge piers with precast footings was tested under a constant axial load and a cyclically reversed horizontal load.

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Quasi-Static Tests for Seismic Performance of Circular RC Bridge Piers (단일주 원형 철근콘크리트 교각의 내진거동에 관한 준정적 실험)

  • 정영수;이강균;한기훈;박종협
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.55-66
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    • 1999
  • Eight RC bridge plers have been made on a 1/3.4 scale model and have been tested in a quasi-static cyclic load so as to investigate their seismic performance. The ultimate objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete plers, which have been widely used for urban transportation facilities in Korea. Improtant test parameters are hoop ratio, axial load, load pattern, and etc. And noninear behaviors of test columns have been evaluated through their yield and ultimate strength, energy dissipation, ductility and load-deflection characteristics under quasi-static cyclic loads. From the quasi-static tests on 8 bridge piers, it is concluded that energy dissipation, ultimate strength and curvature for a given displacement factor ${\mu}={\Delta}/{\Delta}_y$ are higher for the seismically designed columns than for the nonseismically designed columns.

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An Experimental Study on the Absorbed Energy of Polymeric Foam According to Different Mass and Impact Velocity Based on the Constant Impact Energy (동일 에너지 조건하에 충격체 질량과 속도변화에 따른 발포 고분자의 흡수 에너지에 관한 실험적 연구)

  • Kim, Byeong-Jun;Kim, Han-Kook;Cheon, Seong S.
    • Composites Research
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    • v.27 no.2
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    • pp.42-46
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    • 2014
  • In the present study, impact tests were carried out to investigate the crashworthy behaviour of the expanded polypropylene under the constant incident energy (100 J and 200 J) with five different combinations of striker mass and velocity. Also, preliminary quasi-static test was performed to obtain basic characteristics of the expanded polypropylene. MTS 858 and Instron dynatup 9250 HV were used for the quasi-static test and impact tests, respectively. In consequence, it was found that the impact energy absorption characteristics of the expanded polypropylene was more influenced by the striker mass instead of the velocity of the striker.

Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loading Test (강합성교각의 내진성능평가 Part I : 준정적 반복재하실험)

  • 조창빈;서진환;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.2
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    • pp.9-19
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    • 2002
  • Steel piers and concrete-filled steel(CFS) piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as one of alternatives to RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. This paper, the first of two companion papers for the seismic performance of steel and CFS piers, tests steel and CFS piers under quasi-static cyclic loading to estimate their ductility and strength. Additional details such as rebars and base ribs are added to increase the ductility of a concrete-filled steel pier with minimum additional cost. Also, simplified numerical analyses using nonlinear spring and shell elements are examined for the estimation of the ductility and strength of concrete-filled steel piers and a steel pier. The result shows that concrete-filled steel peirs have higher energy absorption, i.e., ductility and strength than those of steel pier and increasing bonding between in-filled concrete and lower diaphragm, and the improved details of stress concentrated region would be important for the ductility and strength of a pier. Numerical results show that simplified modeling with nonlinear springs and shells has potential to be effective modeling technique to estimate the seismic performance of a concrete-filled steel pier.

Experimental Investigation on the Behaviour of CFRP Laminated Composites under Impact and Compression After Impact (CAI) (충격시 CFRP 복합재 판의 거동과 충격후 압축강도에 관한 실험적 연구)

  • Lee, J;Kong, C;Soutis C.
    • Composites Research
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    • v.16 no.4
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    • pp.66-73
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    • 2003
  • The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests. CAI strength and open hole compressive strength tests using 3 mm thick composite plates($[45/-45/0/90]_{3s}$- IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels(between 5.4 J and 18.7 J) follow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. It is identified that the failure behaviour of the specimens from the CAI strength tests was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths art: in good agreement with the measured open hole compressive strengths. considering the impact damage site area, an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.

Anti-Seismic Performance Evaluation of Circular Pier By Interval Reinforcement (보강간격에 따른 원형 기둥부재의 내진 성능 평가)

  • Jang, Il-Young;Kim, Seong-Kyum;Park, Jun-Young;Yang, Jae-Yeol
    • 한국방재학회:학술대회논문집
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    • pp.165-165
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    • 2011
  • 내진 설계규정이 적용되기 이전에 시공되어 사용 중인 교량의 경우 지진 발생시 교각의 파괴 또는 구조적 피해는 교량 전체 시스템의 붕괴를 초래하므로 지진하중에 대하여 피해를 최소화해야 한다. 이를 위해 내진설계규정이 적용되기 이전의 교량 또는 지진취약지역으로 분류된 곳의 교량, 사회적 중요도가 높은 교량에 대해 교각의 내진성능보강을 실시하고 있다. 2007년 말 국토해양부가 관리하고 있는 11,940개 교량 중 지진 발생시 피해가 우려되는 1,342개(일반국도 682개, 고속국도 600개) 교량에 대해 2006년부터 내진보강이 착수되었고 2009년에는 확대 추진하여 일반국도 80개교, 고속국도 100개교에 대한 보강을 실시하였다. 이와 같이 확대 추진되고 있는 정책에 반해, 내진보강 기술 및 제품이 부족하고 새로운 내진보강재 개발이 불가피해지고 있는 것이 현실이다. 소성영역에서의 횡방향 철근은 지진 시 종방향 철근의 좌굴과 콘크리트의 압축강도저하를 방지하며, 전단보강철근으로도 중요한 역할을 하여 교각의 전단강도를 증가시킨다. 그러나 이러한 횡방향 철근은 초기 설계에 의한 시공이 종료된 후 기존의 성능을 증가시키기 위하여 철근량을 증가하거나 단면의 변화를 주기에는 매우 어려운 일이다. 따라서 내진성능을 위한 단면력 증가를 위하여 다양한 재료의 보강재와 형식이 사용되고 있다. 본 연구에서는 원형교각 모델의 구조해석을 이용해 내진성능평가를 선행한 후 실험체를 제작, Helical Bar를 보강하여 준정적 실험을 통해 내진보강성능을 평가하였다. 압축설계강도 $f_{ck}=240kgf/cm^2$를 기준으로 교량등급 2등교인 일반적인 도로교의 1/4축소모형을 설계, 기초부는 $1,200{\times}600{\times}600$ (mm)으로 철근과 콘크리트로 구성하였으며, 기둥부는 직경 400mm, 높이 1,250mm 크기의 철근콘크리트 원형 교각 실험체를 제작하였다. 제작된 실험체는 총 3개로, 분류는 무보강 일반 실험체, Helical Bar 직경에 따른 분류, 보강간격에 따른 분류로 나누어진다.

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The Absorbed Energy of Carbon/Epoxy Composite Laminates Subjected to High-velocity impact in Considering the Loss of Projectile Mass (고속충격을 받는 Carbon/Epoxy 복합재 적층판의 충격체 질량손실을 고려한 흡수에너지 예측)

  • Cho, Hyun-Jun;Kim, In-Gul;Lee, Seokje;Kim, Young-A;Woo, Kyeongsik
    • Composites Research
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    • v.26 no.6
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    • pp.349-354
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    • 2013
  • In this paper, we conducted high velocity impact test for Carbon/Epoxy composite laminates and proposed advanced method for predicting the absorbed energy of composite laminates. During high-velocity impact test, we discovered loss of projectile mass macroscopically using high speed camera, thus we calculated the absorbed energy of composite laminates by taking loss of projectile mass into account. We proposed a model for predicting the absorbed energy of composite laminates subjected to high-velocity impact, the absorbed energy was classified into static energy and dynamic energy. The static energy was calculated by the quasi-static perforation equation that is related to the fiber breakage and static elastic energy. The dynamic energy can be divided by the kinetic energy of deformed specimen and fragment mass. Finally, the predicted absorbed energy considering loss of projectile mass was compared with experimental results.