• Title/Summary/Keyword: reinforcement design

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Basis for the design of lateral reinforcement for high-strength concrete columns

  • Mendis, P.A.;Kovacic, D.;Setunge, S.
    • Structural Engineering and Mechanics
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    • v.9 no.6
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    • pp.589-600
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    • 2000
  • This paper attempts to provide a theoretical basis for the design of high-strength concrete columns in terms of the spacing of lateral reinforcement. In order to achieve this, important concepts had to be addressed such as the choice of a measure of ductile behaviour and a realistic high-strength concrete stress-strain model, as well as limiting factors such as longitudinal steel buckling and lateral steel fracture. A design method incorporating above factors are suggested in the paper. It is shown that both buckling of longitudinal steel and hoop fracture will not demand a reduction in spacing of lateral ties with increase in compressive strength of concrete.

Assessments of the Combined Effect of Installation Damage and Creep on the Long-Term Design Strength of Geogrid for Railroad Reinforcement (철도노반 보강용 지오그리드의 크리프 및 손상이 장기 인장강도에 미치는 영향평가)

  • Lee Do-Hee;Park Tae-Soon;Cho Sam-Deok;Lee Kwang-Wu
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.1156-1161
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    • 2004
  • The factors affecting the long-term design strength of geogrid for railroad reinforcement can be classified into factors on creep deformation, installation damage, temperature, chemical degradation, biological degradation. Especially, creep deformation and installation damage are considered as main factors to determine the long-term design strength of geogrid. This paper describes the results of a series of experimental study, which are carried out to assess the combined effect of installation damage and creep deformation for the long-term design strength of geogrid reinforcement. In this study, a series of field tests are carried out to assess installation damage of a various geogrids according to different fill materials, and then creep tests are conducted to assess the creep properties of both undamaged and damaged geogrids.

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Bulging of Reinforced Retaining Walls (보강토옹벽의 배부름에 관한 실험적 연구)

  • Ju, Jae-Woo;Park, Jong-Beom;Na, Hyun-Ho
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.2
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    • pp.45-53
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    • 2011
  • Recently reinforced retaining walls secure their position as a stabilized method of construction replacing concrete retaining walls gradually. However, in the event of using extensible reinforcement, a bulging phenomenon can be happened in the front of reinforced retaining walls. Bulging of reinforced retaining walls means a phenomenon that, in the height of an arbitrary block, the upper part and the lower part of the block don't secure a relative position in design. Therefore, it is judged that it has the necessity to be examined in design since reinforcement needs metamorphosis to some degree to display tensile force. Therefore, the study examined about how extensibility of reinforcement had an effect on movement of reinforced retaining walls through a small-scale model test with aluminum rods. The study used Changhoji(traditional korean paper made from mulberry bark) as inextensible reinforcement and membrane as extensible reinforcement. As the result of the test, rigidity of reinforcement had a lot of effects on displacement of reinforced retaining walls and generally occurrence point of the maximum horizontal displacement had a tendency transferring to the upper part of walls according to rigidity of reinforcement was increased.

Evaluation of Structural Performance of Flat Plate-Column Interior Connections with Folded Bend Shear Reinforcement (밴드형 전단보강근으로 보강된 무량판 슬래브 내부접합부의 구조 거동 평가)

  • Lee, Bum-Sik;Park, Seong-Sik;Park, Ji-Young;Bang, Jong-Dae;Jun, Myoung-Hoon;Cho, Gun-Hee
    • Land and Housing Review
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    • v.4 no.4
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    • pp.371-382
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    • 2013
  • This study performs an experimental investigation to evaluate the behavior of RC flat plate interior joints specimens. Three 60 percent scale Flat Plate interior specimens assemblies representing a portion of a Flat Plate Apartment Structural System subjected to simulated seismic loading (unbalanced moments) under constant axial load were tested, including one specimens with ordinary shear reinforcement and two specimens with folded bend type shear reinforcement. Test results are shown that (1) the design code KBC 2009 is accurate estimate the behavior of specimens. (2) Two types shear reinforcement have a similar structural behavior, but construction work of rebar with folded bend type shear reinforcement is easier than that of ordinary shear reinforcement. (3) In moderate seismic region, RC Flat Plate interior joint with folded bend type shear reinforcement is apply to structural design of Flat Plate.

A Study on the Flexural Performance of Steel Fiber-Reinforced Beams lightly Reinforced Below the Minimum Steel Reinforcement (최소철근량 이하로 보강된 강섬유보강 보의 휨성능 고찰)

  • Kang, Duk-Man;Park, Yong-Gul;Moon, Do-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.3
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    • pp.35-44
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    • 2017
  • In this study, steel fiber-reinforced concrete beams with ordinary steel reinforcements, that are below minimum steel reinforcement amount specified in domestic concrete structure design code, were tested in flexure until failure. Steel reinforcement ratio considered were 44%, 66%, 78% and 100% of the minimum steel reinforcement. Considered steel fiber volume fractions were 0.25%, 0.50%, 0.75% and 1.00%. In results, it is confirmed that steel fibers greatly improve crack performance. Also, the steel fibers contributed to increment in yield load not in ultimate load. But the increment was not greater than the reduction by steel reinforcement reduction. The use of steel fibers in RC beams lightly reinforced below the minimum reinforcement ratio specified design code reduced ductility greatly. Consequently, steel reinforcement ratio in steel fiber-reinforced beams lightly reinforced below the minimum steel reinforcement should be increased in order to enhance proper ductility.

Development of Optimal Design Technique of RC Beam using Multi-Agent Reinforcement Learning (다중 에이전트 강화학습을 이용한 RC보 최적설계 기술개발)

  • Kang, Joo-Won;Kim, Hyun-Su
    • Journal of Korean Association for Spatial Structures
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    • v.23 no.2
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    • pp.29-36
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    • 2023
  • Reinforcement learning (RL) is widely applied to various engineering fields. Especially, RL has shown successful performance for control problems, such as vehicles, robotics, and active structural control system. However, little research on application of RL to optimal structural design has conducted to date. In this study, the possibility of application of RL to structural design of reinforced concrete (RC) beam was investigated. The example of RC beam structural design problem introduced in previous study was used for comparative study. Deep q-network (DQN) is a famous RL algorithm presenting good performance in the discrete action space and thus it was used in this study. The action of DQN agent is required to represent design variables of RC beam. However, the number of design variables of RC beam is too many to represent by the action of conventional DQN. To solve this problem, multi-agent DQN was used in this study. For more effective reinforcement learning process, DDQN (Double Q-Learning) that is an advanced version of a conventional DQN was employed. The multi-agent of DDQN was trained for optimal structural design of RC beam to satisfy American Concrete Institute (318) without any hand-labeled dataset. Five agents of DDQN provides actions for beam with, beam depth, main rebar size, number of main rebar, and shear stirrup size, respectively. Five agents of DDQN were trained for 10,000 episodes and the performance of the multi-agent of DDQN was evaluated with 100 test design cases. This study shows that the multi-agent DDQN algorithm can provide successfully structural design results of RC beam.

Reasonable Minimum Reinforcement for Crack Control of Concrete Shrinkage (콘크리트 건조수축 균열제어를 위한 합리적인 최소철근량)

  • 김수만;오민호
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.441-444
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    • 1999
  • The crack width of concrete structures subjected to shrinkage depend on a great number of parameters whose effects are restrain condition, the number and spacing of crack and the amounts of reinforcements. Through suitable reinforcement it is possible to make the individual cracks exceedigly small. This paper is to present the amount of reasonable reinforcement for crack control through a rational analysis of forces occuring in significantly restrained concrete structures due to the shrinkage. Also the analysis results from this paper are compared with the provisions for shrinkage and temperture reinforcement in the KCI concrete strucural design code.

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Seismic Reinforcement Detail Comparison of KBC 2009 and KBC 2005 (KBC 2009와 KBC 2005의 내진철근상세 비교)

  • Lee, Hyun-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.173-174
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    • 2010
  • The newly introduced seismic reinforcement details such as special moment frame in KBC 2009 were not perfectly examine in the filed of engineering business. To improve the seismic reinforcement detail's understanding in design code, seismic reinforcement details were compared by using tables and figures.

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Path Planning of Unmanned Aerial Vehicle based Reinforcement Learning using Deep Q Network under Simulated Environment (시뮬레이션 환경에서의 DQN을 이용한 강화 학습 기반의 무인항공기 경로 계획)

  • Lee, Keun Hyoung;Kim, Shin Dug
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.3
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    • pp.127-130
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    • 2017
  • In this research, we present a path planning method for an autonomous flight of unmanned aerial vehicles (UAVs) through reinforcement learning under simulated environment. We design the simulator for reinforcement learning of uav. Also we implement interface for compatibility of Deep Q-Network(DQN) and simulator. In this paper, we perform reinforcement learning through the simulator and DQN, and use Q-learning algorithm, which is a kind of reinforcement learning algorithms. Through experimentation, we verify performance of DQN-simulator. Finally, we evaluated the learning results and suggest path planning strategy using reinforcement learning.

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Comparative Study on Seismic Design of Soil-Reinforced Segmental Retaining Walls (블록식 보강토 옹벽의 내진설계에 관한 비교연구)

  • 유충식
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.51-61
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    • 2000
  • This paper reviews fundamentals of a pseudo-static seismic design/analysis method for soil-reinforced segmental retaining walls. A comparative study on NCMA and FHWA seismic design guidelines, which are one of the most well known design guidelines for mechanically stabilized earth walls, was also performed. The results demonstrate that there exist significant discrepancies in the results of external stability analysis despite the same calculation model used in the two guidelines, due primarily to different seismic coefficient selection criteria. It is also demonstrated that the internal stability calculation model for NCMA guideline tends to yield larger seismic reinforcement force in the shallower reinforcement layers, resulting in an increased number of reinforcement layers at the top of reinforced wall and increased reinforcement lengths to ensure adequate anchorage capacity. The internal stability calculation model adopted by FHWA guideline, however, leads to redistribution of dynamic force to the lower reinforcement layers and thus results n an opposite trend of NCMA guideline. Findings from this study clearly demonstrate a need for more in-depth studies to develop a generally acceptable design/analysis method.

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