• Title/Summary/Keyword: 하중전달율

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Joint Stiffness Evaluation in Jointed Plain Concrete Pavement (줄눈 콘크리트 포장의 줄눈강성 산정 연구)

  • Chon, Beom Jun;Lee, Seung Woo;Kwon, Soon-Min;Kim, Seong-Min
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.1D
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    • pp.49-54
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    • 2009
  • The excellent load transfer at transverse joints ensures the high performance of jointed plane concrete pavements(JPCP). Load transfer efficiency(LTE) is affected by dowel-bars, aggregate interlock and types of underlying layers, and these factors have to be modelled adequately for a reasonable analysis of JPCP. Generally, the joint stiffness has been represented by a spring model for the shear transfer by aggregate interlock or dowels. However dowel-bars, aggregate interlock and types of underlying layers have not been considered together in the design of joints. In this study, the joint stiffness that considered those factors was presented by comparing LTE obtained using FWD(Falling Weight Deflectometer) with theoretical results obtained using the finite element analysis. In addition, the effects of temperature and concrete age, on the joint stiffness were investigated.

Joint Stiffness Tests for Precast Concrete Pavement (프리캐스트 콘크리트 포장의 하중전달 성능 실험)

  • Yang, Sung-Chul;Kim, Seong-Min;Yoo, Tae-Seok;Han, Seung-Hwan
    • International Journal of Highway Engineering
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    • v.10 no.2
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    • pp.229-239
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    • 2008
  • This paper compares the load transfer efficiency between precast concrete pavement specimen and typical concrete pavement specimen by means of laboratory and field tests. An experimental method was developed to evaluate the load transfer efficiency of the dowel bars buried in the concrete pocket and grouted with cement mortar. The test results showed that the load transfer efficiency of the specimen for the dowel bars repaired with grout was equivalent to that of the control specimen. In addition, a series of FWD field tests were conducted on the precast pavement to evaluate the joint stiffness. The field test results revealed that the central deflection of the precast slab slightly increased but the load transfer efficiencies at the joints were almost the same as those in the typical concrete pavement slab.

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Proposals of Indeterminate Strut-Tie Model and Load Distribution Ratio for Design of RC Corbels (철근콘크리트 코벨의 설계를 위한 부정정 스트럿-타이 모델 및 하중분배율의 제안)

  • Chae, Hyun-Soo;Yun, Young-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.197-200
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    • 2008
  • The RC corbels with the ratio of shear span-to-effective depth less than 1 are commonly used to transfer loads from beams to columns. The ultimate strengths and structural behaviors of RC corbels are controlled by the shear span-to-effective depth ratio, strength of concrete, shape and quantity of the reinforcement, and geometry of corbels. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behaviors is presented for the design of RC corbels. In addition, a load distribution ratio, defined as a magnitude of load transferred by a horizontal truss mechanism, is proposed to help structural designers perform the design of RC corbels by using the strut-tie model approaches of current design codes. The ultimate strengths of 30 RC corbels tested to failure are evaluated by using the ACI 318-05's strut-tie model code for the validity check of the proposed indeterminate strut-tie model and load distribution ratio.

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Proposals of Indeterminate Strut-Tie Model and Load Distribution Ratio for Strength Analysis of Pre-tensioned Concrete Deep Beams (프리텐션 콘크리트 깊은 보의 강도해석을 위한 부정정 스트럿-타이 모델 및 하중분배율의 제안)

  • Chae, Hyun-Soo;Ha, Sang-Yong;Yun, Young-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.193-194
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    • 2009
  • In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behavior of pre-tensioned concrete deep beams is presented. In addition, a load distribution ratio, defined as a magnitude of load transferred by a vertical truss mechanism, is proposed to help structural designers perform the strength analysis of pre-tensioned concrete deep beams by using the strut-tie model approaches of current design codes.

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Behavior Characteristics of Railway Roadbed Retained by Geosynthetic Reinforced Segmental Wall Under Train Load (열차 하중 작용 시 블록식 보강토 옹벽으로 지지된 철도 노반의 거동)

  • Lee, Seong Hyeok;Choi, Chan Yong;Lee, Jin Wook
    • Journal of the Korean Society for Railway
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    • v.15 no.5
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    • pp.467-475
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    • 2012
  • Static and dynamic train load tests were conducted to evaluate the train load transfer mechanism in the roadbed which was retained by two types (fully and partially) of segmental retaining walls reinforced by geogrid. The test roadbed was 2.6m high, 5m wide, and 6m long. A combination of earth pressure gages, displacement transducers, and strain gages were placed in specific locations to measure the responses. Test results showed that the wall displacement pattern as well as the earth pressure for the fully reinforced retaining wall was different from those for the partially reinforced retaining wall. In the dynamic train load test, the strain in the upper part of the wall tended to decrease, and both the residual deformation and the rate of the deformation were significantly lower than those in the current design standard.

Redistribution of Negative Moments in Beams Subjected to Seismic Load (지진하중에 대한 보 부모멘트의 재분배)

  • Eom, Tae-Sung;Park, Hong-Gun;Kim, Jae-Yo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.145-146
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    • 2010
  • A moment redistribution method was developed for earthquake design of reinforced concrete moment-resisting frames. For a frame designed with strong column-weak beam, the moment redistribution mechanism was investigated. Based on the result, the relationship between redistributed moment and plastic rotation in plastic hinges was established. By using the relationship, we developed a method for the evaluation of plastic rotations during the moment redistribution, addressing the effects of various design parameters including member stiffness, load condition, and plastic mechanism of structure.

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Evaluation of the Shock Resistance of a Gas Turbine Package (가스터빈 패키지 내충격 성능평가에 관한 연구)

  • Kim, Jae Boo;Park, Yun Ki;Park, Min Seok;Lee, Jong Hwan;An, Sung Chan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.10
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    • pp.1005-1009
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    • 2017
  • In this study, the shock resistance of a gas turbine package subjected to a shock load caused by non-contact underwater explosion was investigated using numerical analysis. To perform shock analysis, the time-history shock load was calculated according to BV-043 (German Navy Regulation). The direct transient response analysis in the time domain for the simplified Whole Engine Model (WEM) was performed using the calculated shock load. In addition, the structural integrity of a detailed model was evaluated by considering the shock load transferred to each component. As a result, it was confirmed that the safety factor was at least 1.0 as compared with the reference stress. Finally, the structural and functional integrity of the Engine Management System (EMS) of the gas turbine package was verified through an actual shock test.

Indeterminate Strut-Tie Model and Load Distribution Ratio of Continuous RC Deep Beams (I) Proposal of Model & Load Distribution Ratio (연속지지 RC 깊은 보의 부정정 스트럿-타이 모델 및 하중분배율 (I) 모델 및 하중분배율의 제안)

  • Kim, Byung-Hun;Chae, Hyun-Soo;Yun, Young-Mook
    • Journal of the Korea Concrete Institute
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    • v.23 no.1
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    • pp.3-12
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    • 2011
  • The structural behavior of continuous reinforced concrete deep beams is mainly controlled by the mechanical relationships associated with the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model which reflects characteristics of the complicated structural behavior of the continuous deep beams is presented. In addition, the reaction and load distribution ratios defined as the fraction of load carried by an exterior support of continuous deep beam and the fraction of load transferred by a vertical truss mechanism, respectively, are proposed to help structural designers for the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure a ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength are implemented after thorough parametric numerical analyses. In the companion paper, the validity of the presented model and load distribution ratio was examined by applying them in the evaluation of the ultimate strength of multiple continuous reinforced concrete deep beams, which were tested to failure.

Load Distribution Ratios of Indeterminate Strut-Tie Models for Simply Supported RC Deep Beams - (I) Proposal of Load Distribution Ratios (단순지지 RC 깊은 보 부정정 스트럿-타이 모델의 하중분배율- (I) 하중분배율의 제안)

  • Kim, Byung Hun;Yun, Young Mook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.2A
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    • pp.259-267
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    • 2008
  • The ultimate strengths of reinforced concrete deep beams are governed by the capacity of the shear resistance mechanism composed of concrete and shear reinforcing bars, and the structural behaviors of the beams are mainly controlled by the mechanical relationships according to the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behaviors is presented for the design of simply supported reinforced concrete deep beams. In addition, a load distribution ratio, defined as a magnitude of load transferred by a vertical truss mechanism, is proposed to help structural designers perform the design of simply supported reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of a load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the prime design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete influencing the ultimate strength and behavior are reflected upon based on various and numerous numerical analysis results. In the companion paper, the validity of presented model and load distribution ratio was examined by employing them to the evaluation of the ultimate strengths of various simply supported reinforced concrete deep beams tested to failure.