• Title/Summary/Keyword: transverse ribs

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Numerical study of internally reinforced circular CFT column-to-foundation connection according to design variables

  • Kim, Hee-Ju;Ham, Junsu;Park, Ki-Tae;Hwang, Won-Sup
    • Steel and Composite Structures
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    • v.23 no.4
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    • pp.445-452
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    • 2017
  • This study intends to improve the structural details of the anchors in the conventional CFT column-to-foundation connection. To that goal, finite element analysis is conducted with various design variables (number and embedded length of deformed bars, number, aspect ratio, height ratio and thickness ratio of ribs) selected based upon the results of loading test and strength evaluation. The finite element analysis is performed using ABAQUS and the analytical results are validated by comparison with the load-displacement curves obtained through loading test applying axial and transverse loads. The behavioral characteristics of the numerical model according to the selected design variables are verified and the corresponding results are evaluated.

Experimental Evaluation on Bond Strengths of Reinforcing Bar in Coils with Improved Machinability during Straightening Process (직선화 가공성을 고려한 코일철근의 실험적 부착강도 평가)

  • Chun, Sung-Chul;Choi, Oan-Chul;Jin, Jong-Min
    • Journal of the Korea Concrete Institute
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    • v.25 no.1
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    • pp.53-61
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    • 2013
  • A new deformation of reinforcing bar in coils was proposed to improve a machinability of straightening process, which has crescent-shaped transverse ribs with an inclination angle of 50 degrees, a crest width of $0.15d_b$, and a flank inclination of 55 degrees. The proposed deformation can increase contact area between a surface of re-bar and a groove of a roller during a straightening process and, therefore, it might reduce a damage of ribs, improve a final straightness, and enhance an efficiency of the straightening process. Splice tests were conducted to evaluate bond strengths of three types of re-bar in coils including the proposed re-bar, of which the inclination angles of transverse ribs were 50, 60, and 90 degrees, respectively. Test results show that the re-bars in coils have higher bond strengths than predicted strengths by equations of Orangun et al., ACI 408, and KCI by at least 10%. Correlation coefficients of bond strengths between a straight bar and re-bars in coils are 0.94 and more. Consequently, equations of the KCI code for determining development and splice lengths can be applied to the tested re-bars in coils.

A case of fused thoracic vertebrae, and lumbar vertebrae, sacrum and ilium of African elephant (Loxodonta africana) were fused one another partially (아프리카코끼리(Loxodonta africana)의 흉추골유합과 요추골, 천골 및 장골이 유합된 1례)

  • Kim, Chong-sup;Won, Chung-kil;Cho, Gyu-hen;Cho, Kyu-woan;Park, Joong-suk;Rho, Gyu-jin
    • Korean Journal of Veterinary Research
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    • v.42 no.2
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    • pp.131-136
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    • 2002
  • The vertebrae of female African elephant (Loxodonta africana) of twenty-eight years old were observed macroscopically. The result was summarized as follows; the vertebral formula of African elephant was $C_7$ $T_{21}$ $L_3$ $S_4$ $Cd_{21}$. The total length of the vertebral column removed intervertebreal disks was 353 cm. The length of each segment of vertebral column was 44 cm in cervical, 142 cm in thoracic, 21 cm in lumbar, 27 cm in sacral and 119 cm in caudal vertebrae. The 17th and 18th thoracic vertebrae (T) were partially fused each other in four parts: the transverse processes of 17th and 18th T, caudal articular process of 17th T and cranial articular process of 18th T, left mammilary process of 18th T and left transverse process of 17th T, and vertebral arch of 17th and 18th T, respectively. Others partial fusions also observed among the third luwbar, sacrum and ilium. These were in between transverse process of third lumbar vertebra and cranial parts of wing of sacrum, lateral part of sacrum and tuber sacrale, respectively. The sternum was consisted of three pieces; one is a part of anterior prestemum, two is the part from caudal demifacet at second facet to cranial demifacet at third facet in middle mesosternum, which is divided vertically into an half at second and third facets, respectively, and the last is the part between caudal demifacet of third facet in middle mesosternum and the posterior xiphisternum. There are 21 pairs of ribs, six sternal, ten asternal ribs and the last five being floating ribs.

Numerical analysis on heat transfer and pressure drop characteristics in a horizontal channel with various ribs (여러 가지 형태의 립이 설치된 수평채널의 열전달 및 압력강하 특성에 관한 수치해석)

  • Kim, Ji-Hoon;Heo, Joo-Nyoung;Ahn, Sung-Hoo;Lee, Doo-Ho;Son, Young-Seok;Shin, Jee-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.1
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    • pp.40-46
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    • 2013
  • Turbulent flow and heat transfer in a channel with a detached rib array have been simulated. The computations are based on the finite volume method with the SIMPLE algorithm. The forms of ribs considered in this study were rib with rectangular cross section, rib with groove, broken rib, and V-shaped rib. The ribs were deployed transverse or aligned $60^{\circ}$ to the main direction of the flow. Local heat transfer coefficients were obtained at various Reynolds numbers within the turbulent flow regime. Area-averaged data were calculated in order to compare the overall performance of the tested ribbed surfaces and to evaluate the degree of heat transfer enhancement induced by the ribs with respect to the smooth channel. The highest heat transfer occurred for the rib with groove which was aligned $60^{\circ}$ to the main flow direction. Performance factor was decreased with the increase of velocity, and it was found that the best performance factor was obtained in the low velocity region.

Radiographic evaluation of congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis)

  • Lee, Eun Gee;Park, Sool Yi;Lee, Kija;Jang, Min;Kim, Jong Taek;Choi, Sooyoung;Park, Inchul
    • Journal of Veterinary Science
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    • v.22 no.4
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    • pp.52.1-52.8
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    • 2021
  • Background: The normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies. Objectives: This retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis). Methods: Radiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine. Results: Normal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6. Conclusions: This study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.

Stress Concentration at Connection and Cut-Out Parts according to Existence of Scallop and Diaphragms on Orthotropic Steel Decks (강바닥판의 스캘럽·다이아프램 설치 유무에 따른 교차부·컷아웃부 응력집중)

  • Shin, Jae Choul
    • Journal of Korean Society of Steel Construction
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    • v.18 no.3
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    • pp.289-299
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    • 2006
  • Orthotropic steel decks are manufactured by welding thin plates therefore it is inevitable that there are abundant works of welding process. On connection of transverse rib web, crossing point of longitudinal rib, transverse rib and deck plate and cut-out parts of transverse rib are the significant position of stress concentration phenomenon because of out of plane and oil-caning deformation caused by longitudinal rib distortion with shear force and distortion. In order to reduce the stress concentration phenomenon and improving fatigue performance at the crosing point and cut-out, structural analysis was performed considering the existence of scalop at conection and diaphragm which have same plane with transverse rib placed inside of longitudinal rib. Result o f the analysis show that there are the largest efect of stres concentration reduction when diaphragms are installed without scallop at connection, therefore these detail can improve the fatigue performance of orthotropic steel decks.

Heat Transfer and Frictions in the Rectangular Divergent Channel with Ribs on One Wall

  • Lee, MyungSung;Ahn, SooWhan
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.352-357
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    • 2016
  • An investigation of ribbed divergent channel was undertaken to determine the effect of rib pitch to height ratio on total friction factor and heat transfer results in the fully developed regime. The ribbed divergent rectangular channel with the channel exit hydraulic diameter ($D_{ho}$) to inlet channel hydraulic diameter ($D_{hi}$) ratio of 1.16 with wall inclination angle of 0.72 deg, at which the ratios (p/e) of 6,10, and 14 are considered. The ribbed straight channel of $D_{ho}/D_{hi}=1.0$ were also used. The ribbed divergent wall is manufactured with a fixed rib height (e) of 10 mm and the ratio of rib spacing (p) to height 6, 10, and 14. The measurement was run with range of Reynolds numbers from 24,000 to 84,000. The comparison shows that the ratio of p/e=6 has the greatest thermal performance in the divergent channel under two constraints; identical mass flow rate and identical pressure drop.

Machine learning-based probabilistic predictions of shear resistance of welded studs in deck slab ribs transverse to beams

  • Vitaliy V. Degtyarev;Stephen J. Hicks
    • Steel and Composite Structures
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    • v.49 no.1
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    • pp.109-123
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    • 2023
  • Headed studs welded to steel beams and embedded within the concrete of deck slabs are vital components of modern composite floor systems, where safety and economy depend on the accurate predictions of the stud shear resistance. The multitude of existing deck profiles and the complex behavior of studs in deck slab ribs makes developing accurate and reliable mechanical or empirical design models challenging. The paper addresses this issue by presenting a machine learning (ML) model developed from the natural gradient boosting (NGBoost) algorithm capable of producing probabilistic predictions and a database of 464 push-out tests, which is considerably larger than the databases used for developing existing design models. The proposed model outperforms models based on other ML algorithms and existing descriptive equations, including those in EC4 and AISC 360, while offering probabilistic predictions unavailable from other models and producing higher shear resistances for many cases. The present study also showed that the stud shear resistance is insensitive to the concrete elastic modulus, stud welding type, location of slab reinforcement, and other parameters considered important by existing models. The NGBoost model was interpreted by evaluating the feature importance and dependence determined with the SHapley Additive exPlanations (SHAP) method. The model was calibrated via reliability analyses in accordance with the Eurocodes to ensure that its predictions meet the required reliability level and facilitate its use in design. An interactive open-source web application was created and deployed to the cloud to allow for convenient and rapid stud shear resistance predictions with the developed model.

Relief Hole for Improvement of Fatigue Strength in Welded Intersections of Transverse and Longitudinal Ribs in Orthotropic Deck (가로리브와 U리브 용접부의 피로강도 향상을 위한 응력완화홀)

  • Jung, Kyoung Sup;Nam, Seung Hoon;Yang, Keon Bong;Kim, Kyoung Nam
    • Journal of Korean Society of Steel Construction
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    • v.26 no.5
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    • pp.419-430
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    • 2014
  • On going researches which are being made on the welded joints at the intersections of closed ribs such as U-ribs with floor-beams in ortho-tropic steel decks still have been used the shape of scallops with or with not diaphragm inside. Stress Relief Hole(SRH) being presented in this study was investigated in order to reduce the fatigue damage in the intersections of U-rib with floor-beam. Finally, it is verified that circular SRHs sufficiently relief the concentration stress at the intersections of U-rib with floor-beam and shows that SRH can be offer one of the methods that can prevent the fatigue damage in these structural details.

Evaluation of Static Behaviour of Orthotropic Steel Deck Considering the Loading Patterns (하중재하 패턴을 고려한 강바닥판의 정적거동 평가)

  • Kim, Seok Tae;Huh, Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.2
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    • pp.98-106
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    • 2011
  • The deck of steel box girder bridges is composed of deck plate, longitudinal rib, and transverse ribs. The orthotropic steel decks have high possibility to fatigue damage due to numbers of welded connection part, the heavy contact loadings, and the increase of repeated loadings. Generally, the local stress by the repeated loadings of heavy vehicles causes the orthotropic steel deck bridge to fatigue cracks. The increase of traffic volume and heavy vehicle loadings are promoted the possibility of fatigue cracks. Thus, it is important to exactly evaluate the structural behavior of bridge considering the contact loading area of heavy vehicles and real load patterns of heavy trucks which have effects on the bridge. This study estimated the effect of contact area of design loads and real traffic vehicles through the finite element analysis considering the real loading conditions. The finite element analysis carried out 4 cases of loading patterns in the orthotropic steel deck bridge. Also, analysis estimated the influence of contact area of real truck loadings by the existence of diaphragm plate. The result of finite element analysis indicated that single tire loadings of real trucks occurred higher local stress than one of design loadings, and especially the deck plate got the most influence by the single tire loading. It was found that the diaphragm attachment at joint part of longitudinal ribs and transverse ribs had no effects on the improvement of structural performance against fatigue resistance in elastic analysis.