• Title/Summary/Keyword: 정적재하시험

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Behavior Analysis of Ultra-Thin Whitetopping in Field (얇은 콘크리트 덧씌우기 포장의 거동 평가)

  • Kang, Jang-Hwan;Jang, Jin-Yen;Koo, Han-Mo;Cho, Yoon-Ho
    • International Journal of Highway Engineering
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    • v.6 no.1 s.19
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    • pp.25-36
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    • 2004
  • The total length of paved roads in Korea is 67,265 Km, and among these roads, about 40% of the national highways and 98% of local roads are paved with asphalt concrete. The major distress to asphalt pavement is rutting and fatigue crack. The permanent deformation including rutting accounts for about 75% of this distress. UTW(Ultra-Thin Whitetopping), which is known for its high-quality performance in asphalt pavement with rutting and cracking, seems to reduce maintenance costs significantly if it is used as the maintenance/repair method for domestic asphalt pavement. In the research, static load test was conducted to establish a behavior of Whitetopping under traffic and environmental condition. It showed that the effect of the thickness of the concrete layer and the temperature change was significant. In addition, the tensile strain as the wheel load position was close to interior and edge of concrete slab were increased up to 75% of maximum tensile strain. It showed that joint spacing must be considered in UTW design procedure.

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Evaluation of Bearing Capacity of Piles in Sand Using Pile Driving Analyzer (동재하시험을 이용한 모래지반의 말뚝지지력 산정)

  • 이우진;석종수
    • Geotechnical Engineering
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    • v.13 no.5
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    • pp.145-154
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    • 1997
  • Though the static pile load tests gives the mosts accurate estimation on the load carrying capacity of tested pile, it appears time-consuming and not economical. Many test methods using equipments, such as Pile Driving Analyzer(PDA), STATNAMIC, and Osterberg cell, have been introduced in Korea, and pile best using PDA has been gaining popularity because of iris fast and simple operation. Static and dynamic tests results on the piles installed in the granular coils were analyzed to investigate the effect of geometrical damping on the estimated load carrying capacity. It was found that the CAPWAP analysis without considering geometrical damping effect underestimates the pile capacity by 30~60% under certain conditions. It was observed that the underestimation of pile capacity by CAPWAP occurs on the piles installed in the water-borne granular boils by SIP methods. When Smith skin damping value(SSkn) greater than 1.0 sec/m is obtained in CAPWAP analysis, it may reflect the large possibility of underestimation of pile capacity. The introduction of the geometircal damping option in CAPWAP analysis gives reasonable pile capacity, compared with the static pile load test results, and reduces the SSb value under 0.7 sec/m.

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A Study on the Field Application of the Measurement Technique for Static Displacement of Bridge Using Ambient Vibration (상시 진동을 이용한 교량 정적 처짐 산정 기술의 현장 적용성 연구)

  • Sang-Hyuk Oh;Dae-Joong Moon;Kwang-Myong Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.4
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    • pp.355-363
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    • 2023
  • In safety assessment of a aged bridge, dynamic characteristics and displacement are directly related to the rigidity of the structural system, especially displacement is the most important factor as the physical quantity that the bridge user can directly detect. However, in order to measure the displacement of the bridge, it is difficult to install displacement sensors at the bottom of the bridge and conduct traffic blocking and loading tests, resulting in increased costs or impossible measurements depending on the bridge's environment. In this study, a method of measuring the displacement of a bridge using only accelerometers without installing displacement sensors and ambient vibration without a loading test was proposed. For the analysis of bridge dynamic characteristics and displacement using ambient vibration, the mode shape and natural frequency of the bridge were extracted using a TDD technique known to enable quick analysis with simple calculations, and the unit load displacement of the bridge was analyzed through flexibility analysis to calculate static displacement. To verify this proposed technology, an on-site test was conducted on C Bridge, and the results were compared with the measured values of the loading test and the structural analysis data. As a result, it was confirmed that the mode shape and natural frequency were 0.42 to 1.13 % error ratio, and the maximum displacement at the main span was 3.58 % error ratio. Therefore, the proposed technology can be used as a basis data for indirectly determine the safety of the bridge by comparing the amount of displacement compared to the design and analysis values by estimating the displacement of the bridge that could not be measured due to the difficulty of installing displacement sensors.

Comparison of Elastic Moduli of Subgrade Soils Using Plate Loading Test, Soil Stiffness Gauge and Dynamic Cone Penetrometer (평판재하시험, 흙강성측정기 및 동적콘관입시험기를 이용한 노상토의 탄성계수 비교)

  • Kim, Kyu-Sun
    • Journal of the Korean Geotechnical Society
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    • v.31 no.3
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    • pp.63-72
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    • 2015
  • This paper describes the correlation and relationship between elastic moduli measured by three stiffness measurement methods with different mechanical characteristics to evaluate the compaction characteristics of subgrade soils. The Soil Stiffness Gauge (SSG) with very small strain (${\approx}0.001%$) ranges, static Plate Loading Test (PLT) with mid-level strain (${\approx}0.01{\sim}0.1%$) ranges, and Dynamic Cone Penetrometer (DCP) using penetration resistance were implemented to measure the elastic modulus. To use the elastic modulus measured by different measurement methods with a wide range of strain in practice, it is required to identify the correlation and relationship of measured values in advance. The comparison results of the measured elastic moduli ($E_{SSG}$, $E_{PLT}$, $E_{DCP}$) using the three measurement methods for domestic and overseas subgrade soils under various conditions indicate that the evaluated elastic modulus relies on the types of soils and the level of stress condition. The correlation analysis of the measured elastic moduli except the data of cement treated soils indicates that the static elastic modulus ($E_{PLT}$) is evaluated as about 60 to 80% of the dynamic elastic modulus ($E_{SSG}$). Unusual soils such as cement treated soils are required to be corrected by the stress correction during the correlation analysis with typical soils, because these types of soils are sensitive to the stress condition when measuring the static elastic modulus ($E_{PLT}$) of soils. In addition, when considering the use of DCP data for the evaluation of the elastic modulus ($E_{DCP}$), the measured data of the elastic modulus less than 200 MPa show more reliable correlation.

Mechanical Performance Evaluation of RC Beams with FRP Hybrid Bars under Cyclic Loads (FRP 하이브리드 보강근을 가지는 RC보의 반복하중에 대한 역학적 성능 평가)

  • Hwang, Chul-Sung;Park, Jae-Sung;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.1
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    • pp.9-14
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    • 2017
  • In the present work, a mechanical performances under cyclic loading in RC (Reinforced Concrete) beams with normal steel and FRPH (Fiber Reinforced Plastic Hybrid) bar are investigated. For the work, RC beam members with $200{\times}200{\times}2175mm$ of geometry and 24 Mpa of design strength are prepared, and 4-point-bending tests are performed for evaluation of cracking, yielding, and ultimate loads. Through static loading test, 48.9kN and 36.0 kN of yielding loads are measured for normal RC and FRPH beam, respectively. They have almost same ultimate load of 50.0 kN. Typical tension hardening behavior is observed in FRPH beam, which is caused by the behavior of FRPH bar with tension hardening. In cyclic loading conditions, FRPH beam has more smaller crack width and scattered crack pattern, and it shows more elastic recovery than normal RC beam. The energy dissipation ratio in FRPH beam is 0.83, which is greater than 0.62 in normal RC beam and it shows more effective resistance to cyclic loadings.

Compare and Analysis of the Cases of Load Capacity Evaluation of Existing Bridges (교량 내하력 평가사례의 비교 고찰 및 분석)

  • 오병환;신호상;한승환;이상민;이태규
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.391-395
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    • 1995
  • 본 연구에서는 현재 각 연구기간에서 실시되고 있는 기존 교량의 내하력 평가사례 들을 비교 분석하고, 이에 따른 문제점을 도출하여 보다 합리적인 교량 내하력 평가기법을 제시하고자 한다. 내하력 평가내용 중 외관조사 방법, 정적 및 동적 재하시험 및 결과분석, 대상교량의 구조해석 및 최종 내하력 평가 방법에 따라 분석하고 이에 따른 각 연구기관별 수행 방법의 차이를 기술하고 문제점을 도출하여 개선된 내하력 평가기법의 방향을 제시하 고자 한다. 분석결과 실측치와 해석치 사이에 차이가 많이 존재하고 평가방법도 일관성이 결여되어 있는 것으로 나타나고 있다.

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An Application of Dynamic Loading Test of Precast Module Concrete Decks (프리캐스트 모듈 바닥의 동하중 재하시험)

  • Sung, Ikhyun
    • Journal of the Society of Disaster Information
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    • v.13 no.1
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    • pp.73-80
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    • 2017
  • In this study, the panel joint behavior by the vehicle load moving on precast panel is analyzed. The frame was made for loading and the behavior was determined by using each measuring device. The static response of the panel was examined and compared with the theoretical value, and it was found that the characteristics were very reasonable. In addition, acceleration, velocity, and displacement were measured for dynamic impact evaluation, and the characteristics of moving load were analyzed in the test. The vibration frequency of the panel was measured for the dynamic response by the moving load, and the vibration characteristic was considered to be sensitive to the range of the load. As a result, it is considered that the dynamic response of the connection part should be careful in design because the characteristics are different according to the connection method.

A Study on the Static and Fatigue Behavior of Steel-Confined Prestressed Concrete Girder (강재로 구속된 프리스트레스트 콘크리트 합성거더의 정적 및 피로거동)

  • Kim, Jung Ho;Park, Kyung Hoon;Hwang, Yoon Koog;Lee, Sang Yoon
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6 s.73
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    • pp.725-736
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    • 2004
  • A new type of girder, called steel-confined prestressed concrete girder (SCP girder), has been developed, which maximizes the structural advantages of concrete, steel, and PS tendon, and improves on the shortcomings of steel plate girder, PSC I-girder, and preflex girder bridge for use in the construction of middle- or long-span bridges. To verify the propriety of design, structural safety, and applicability of this girder, a static load test was carried out (Kim et al.., 2002). Since the main damage typically sustained by steel bridges results from the fatigue caused by the repetition of traffic loads, fatigue safety must therefore be guaranteed in applying the SCP girder in the construction of real bridges. In this study, a fatigue test was carried out to investigate fatigue behavior and provide basic data for fatigue design. Based on the fatigue test, the fatigue safety of the girder was estimated. For the fatigue test, 10-m specimens were designed for a standard-design truckload (DB-24). A static load test was also performed before the fatigue test to analyze the structural behavior of the specimens. After the fatigue test, outer steel plates were removed to observe the condition of the concrete in the girder.

A Study on the Continuation Effect of the PC Beam Bridge Reinforced by Span-Jointing of Slab (PC Beam 교의 슬래브 연속화 보강 효과에 대한 연구)

  • Sun, Chang-Ho;Lee, Jong-Seok;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.4
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    • pp.225-232
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    • 2002
  • Recently the slab span-jointing method has been employed as one of the retrofit technologies to enhance the capacity of existing simple beam bridges in many cases. In general this method makes simple beam bridges behave like multi-span continuous bridges under service loads excluding self weight in company with external prestress force method in the field. In this paper the continuation effect has been studied for the retrofitted bridges by the experimental and numerical approaches. The results show that the deflections and stresses of members are reduced due to the increase of the total stiffness of bridge system and the efficiency of bridge continuation based on the slab span-jointing method is about 40 % when comparing with the case of continuous bridges.

A Structural Performance Test of a Full-scale Pretension PSC Girder (실물모형 프리텐션 PSC 거더의 구조성능 시험)

  • Kim, Tae Kyun;Lee, Doo Sung;Lee, Sung Chul
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.5
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    • pp.1741-1751
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    • 2013
  • The main purpose of this study is to investigate the static behavior of a prestressed concrete (PSC) girder using pre-tension method. A 30m long full-scale pretension PSC girder is fabricated by the portable fabrication system and tested. All results have been compared to those obtained from F.E.A results. Deflections at the middle of girders have been measured for evaluation. Also, strains of concrete at the middle of span have been measured. From the results of experimental, the load when initial crack was developed was obtained to be 1.75 time the unfactered design load in the full-scale girder specimen. Also, the data of specimen are satisfied the desgin requirements of ductility on the Korea Bridge Design Specification(2010). In service state, the vertical deflection at center of test specimen when a initial crack was developed is satisfied the vertical deflection requirement under live load of the Korea Bridge Design Specification(2010). To verify the experimental results, we numerical analyze the test and confirmed that the data were similar with results from the test above. The pretension girder fabricated in site were found to have enough strength for safety under and after construction.