• Title/Summary/Keyword: Shear span to depth ratio

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Development of DCOC Algorithm Considering the Variation of Effective Depth in the Optimum Design of PRC Continuous Beam (PRC연속보 최적설계에서 단면의 유효깊이 변화를 고려한 DCOC알고리즘 개발)

  • 조홍동;한상훈
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.281-291
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    • 2002
  • This paper describes the minimum cost design of prestressed reinforced concrete (PRC) hem with rectangular section. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non prestressing steel, and formwork is minimized. The design constraints include limits on the minimum deflection, flexural and shear strengths, in addition to ductility requirements, and upper-Lower bounds on design variables as stipulated by the specification. The optimization is carried out using the methods based on discretized continuum-type optimality criteria(DCOC). Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables - effective depth, eccentricity of prestressing steel and non prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. In this paper the effective depth is considered to be freely-varying and one uniform for the entire multispan beam respectively. Also the maximum eccentricity of prestressing force is considered in every span. In order to show the applicability and efficiency of the derived algorithm, several numerical examples of PRC continuous beams are solved.

Analysis of Structural Performance of Wood Composite I and Box Beam on Cross Section Component (I) - Calculation and Analysis of Flexural Rigidity and Deflection - (단면구성요소(斷面構成要素)에 관(關)한 목질복합(木質複合) I및 Box형 보의 구조적(構造的) 성능(性能) 분석(分析) (I))

  • Oh, Sei-Chang;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.19 no.2
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    • pp.40-55
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    • 1991
  • To investigate the influence of cross section geometries on the behavior of composite beams in the case of small span to depth ratio and deep beams. the static flexural behavior of composite I-beams and Box- beams was evaluated. 12 types of composite I -beams composed of LVL flanges and particleboard or plywood web and 3 types of composite Box-beams composed of LVL flanges and plywood web were tested under one-point loading. The load-deflection curves were almost linear to failure, therefore, the behavior of tested composite beams was elastic. The theoretical flexural rigidity of composite beams was calculated and compared with observed flexural rigidity. The highest value was found in I-W type beams and the lowest value was found in G-P type beams. The difference between theoretical and observed flexural rigidity was small. Theoretical total deflection of tested composite beams was calculated using flexural rigidity and compared with actual deflection. Shear deflection of these beams was evaluated by the approximation method, solid crosss section method and elementary method. The difference between actual deflection and expected deflection was not found in D, E and F type beams. This defference was small in G, H and I type beams or Box-beam.

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Experimental Study on Flexural Structural Performance of Sinusoidal Corrugated Girder (파형 웨브주름 보의 휨성능에 관한 실험적 연구)

  • Kim, Jong Sung;Chae, Il Soo
    • Journal of Korean Society of Steel Construction
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    • v.27 no.6
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    • pp.503-511
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    • 2015
  • In long span steel structure, the plate girder reinforced with stiffeners are commonly used. When choosing the cross section with deep depth of girder as well as narrow width, however, out of plane buckling can be a problem due to web slenderness. In an effort to solve this issue, current study determined the applicability of using corrugated web girder with deep depth as bending member, which is generally being utilized in both factory and warehouse nationwide. To accomplish this, we performed the loading test of H-shaped beam with sinusoidal corrugated web. Corrugated web CP-2.3 specimen exhibited 12% less maximal bending strength but CP-3.2 specimen exerted 24% increase in strength compared to plate web P-4.5. this result indicates that corrugated web provides enough strength even with unfavorable width-thickness ratio of plate. And bending as well as shear strength estimated by the Eurocode (EN 1993-1-5) were compared with both bending strength by loading test and shear strength estimated by KBC2009. In case of eurocode, increase in plate thickness did not help in bending performance improvement. moreover, shear performance was sensitive to the thickness of the web folds and the shape of the web plate.

Fiber Type Effects on the Flexural Behavior of Steel Fiber Reinforced Concrete Beams (강섬유의 형태에 따른 SFRC보의 휨거동에 관한 연구)

  • Jeon, Chan Ki
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.12 no.4
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    • pp.95-106
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    • 1992
  • This paper presents a comparative evaluation of five different types of steel fibers used as reinforcing material in concrete beams. Two types of plain and RC beams were prepared to compare the relative flexural behavior. The fibers used were dog bone (paddled), both ends hooked. コ-type straight. crimped and wavy type with aspect ratio of 43 to 75. Fiber volume fraction of 1 to 2% were used while shear span to depth ratio (aid) and steel ratio p were fixed. Fiber reinforcement effect index Ef and effective toughness index Te were adopted to evaluate fiber reinforcing effects. The effect of fiber reinforcement on flexural strength is higher in plain beams than in RC beams. Hooked and dog bone type fibers were found to be more effective than the other type ones in enhancing the flexural strength and post-peak energy absorption capacity of concrete beams.

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Failure Behaviour and Shear Strength Equations of Reinforced Concrete Deep Beams (철근콘크리트 깊은 보의 파괴거동과 전단강도 산정식)

Analysis of Structural Performance of Wood Composite I and Box Beam on Cross Section Component (II) - Calculation and Analysis of Ultimate Loads - (단면구성요소(斷面構成要素)에 관(關)한 목질복합(木質複合) I 및 Box형(形) 보의 구조적(構造的) 성능(性能) 분석(分析) (II) - 최대하중(最大荷重)의 계산(計算) 및 해석(解析) -)

  • Oh, Sei-Chang;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.19 no.3
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    • pp.62-71
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    • 1991
  • An evaluation of bending test of composite I and Box beams for determining the ultimate strength limit design criteria was presented. Maxium loads of composite I beams were found in beams composed of thicker upper flanges and/or vertical LVL flanges. These loads of plywood web beams were greater than those of PB web beams. Maximum loads of unsymmetrical box beams were less than those of symmetrical box beams. Thus, it took on different phase in box type beams. Ultimate loads of composite beams were greater than those of solid. The failure of composite beams were abrupt and failure mode was classified into following categories; Edgewise shear failure in web, delamination in flange-web joint, tension failure and tearing in LVL flanges, and web delamination. These failures of composite beams were appeared at the mixed mode. The influence factor affecting the performance of tested composite beams was shear strength of PB-web composite beams and compressive strength in plywood-web composite beams. It was also assumed that the influence factors on structural performance on composite beams were flange quality, web material and geometry of cross section. As one of the design methods resisting to compressive stress that was required in the case of small span to depth ratio and deep beams. composite I-beams composed of thicker upper flanges comparing to lower flanges were very effective in structural performance.

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Discrete Optimum Design of Reinforced Concrete Beams using Genetic Algorithm (유전알고리즘을 이용한 철근콘크리트보의 이산최적설계)

  • Hong, Ki-Nam;Han, Sang-Hoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.1
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    • pp.259-269
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    • 2005
  • This paper describes the application of genetic algorithm for the discrete optimum design of reinforced concrete continuous beams. The objective is to minimize the total cost of reinforced concrete beams including the costs of concrete, form work, main reinforcement and stirrup. The flexural and shear strength, deflection, crack, spacing of reinforcement, concrete cover, upper-lower bounds on main reinforcement, beam width-depth ratio and anchorage for main reinforcement are considered as the constraints. The width and effective depth of beam and steel area are taken as design variables, and those are selected among the discrete design space which is composed with dimensions and steel area being used from in practice. Optimum result obtained from GA is compared with other literature to verify the validity of GA. To show the applicability and efficiency of GA, it is applied to three and five span reinforced concrete beams satisfying with the Korean standard specifications.

Prediction of Bending Strength of Concrete Beams with Compressive Strength of 80 MPa (80 MPa의 압축강도를 갖는 콘크리트 보의 휨강도 예측)

  • Kim, Kyoung-Chul;Yang, In-Hwan;Joh, Chang-Bin
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.335-343
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    • 2017
  • This paper aims at investigating the bending strength of high-strength concrete beams with compressive strength of 80 MPa. The experimental parameters included nominal yielding strength of rebar with 400 and 600 MPa, rebar ratio ranging from 0.98 to 1.97%, and shear span-effective depth ratios (a/d) of 6.0 and 4.8. Experimental results were discussed regarding load-deflection relationship, ductility, bending strength, and prediction of bending strength of beams. Test results indicate that the use of high-strength rebar increased bending strength but decreased ductility. As span-effective depth ratio increased, the ductility of test beams decreased. In addition, test results of bending strength were compared with predictions from the current KCI code, Eurocode 2 and Korean Highway Design Specification (KHDC). The design code predictions for bending strength underestimated the experimental results. Therefore, the current design code predictions for bending strength of high-strength concrete beams would provide conservative design. Predictions of bending strength from KCI code using strength reduction factors and those from Eurocode 2 as well as KHDC using material factors were similar each other.

Effects of Axial Force on Deformation Capacity of Steel Encased Reinforced Concrete Beam-Columns (매립형 SRC 기둥재의 변형성능에 대한 축력의 영향)

  • Chung, Jin-An;Yang, Il-Seung;Choi, Sung-Mo
    • Journal of Korean Society of Steel Construction
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    • v.15 no.3
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    • pp.251-259
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    • 2003
  • In this paper, an analytical approach hwas been conductsed to clarify the relationships between the axial force and the deformation capacity of steel- encased reinforced- concrete beam-columns. The analytical model was defined as a cantilever. Several parameters influencing the inelastic performance of the beam-columns were selected, as follows: including encased steel area ratios, and sectional shapes of the encased steel, material strengths, and shear-span- to-depth ratios. The Analytical results of the analysis showed that the axial force had to have a maximum limit to ensure the stable behavior of a steel- encased reinforced- concrete beam-column when it was subjected to both axial and repeated lateral loading under a constant rotation angle amplitude. The maximum axial force of the beam-column to be resisted under cyclic lateral loading was defined as the stable-limit axial force to ensure the required rotation angle amplitude. The Analytical results of the analysis indicate that the stable-limit axial load ratio increases as the steel strength increases or as the compressive strength of the concrete decreases. The stable-limit axial load ratio decreases as the encased steel ' s sectional area increases in the case of a 1-shaped sections and it is almost not influenced by the steel sectional area in the case of a cross-shaped section.

Study on Affecting Factors for the Segmental Joint Behavior of Spliced Girder Bridges (분절교량 접합부 거동의 영향인자에 대한 연구)

  • Nam, Jin-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.3
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    • pp.9-16
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    • 2019
  • Recently, precast PSC girder bridges have been widely applied for short and middle span bridges. The construction of the spliced girder bridges has been increasing to overcome the length limit of girder and transportation restrictions. In case of the spliced girder, the integrity of the segmental joints is very important to secure the structural soundness of bridge because the discontinuity on the segmental joints between adjacent segments could be vulnerable point. The study of segmental joint behavior with different influence factors of joint type, shear key installation, confining force is very important. In this research, finite element analysis and scaled model test with different shear key shapes and confining forces were carried out and the comparative study was performed to evaluate the segmental joint behavior of precast spliced PSC girder bridge. It was confirmed that the installation of shear key with height and depth ratio of 1/2~1/3 and applying of confining force of 1/2 of the concrete strength at the joint was effective in improving the integrity of segmental joint. In addition, the field loading test for existed precast spliced PSC girder bridge was performed and the measurement of the difference of deflection between adjacent segments at segmental joint was proposed as the assessment solution of the integrity of segmental joint.