Processing math: 100%
  • Title/Summary/Keyword: 편심도

Search Result 615, Processing Time 0.075 seconds

Half-Scaled Substructure Test for the Performance Evaluation of a Transmission Tower subjected to Wind Load (송전철탑의 내풍안전성 평가를 위한 1/2축소부분구조 실험)

  • Moon, Byoung-Wook;Min, Kyung-Won
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.20 no.5
    • /
    • pp.641-652
    • /
    • 2007
  • In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, is was confirmed that the calculated axial forces of tower leg members were distributed to 8090 of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.

Stress Block of High Strength Polymer Concrete Flexural Members (고강도 폴리머 콘크리트 휨부재의 응력블럭)

  • 김관호;김남길;연규석
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.5
    • /
    • pp.638-644
    • /
    • 2002
  • The stress-strain relationship of polymer concrete flexural member was evaluated using C-shaped polyester concrete specimen, the compressive strength of which is 1400 kgf/cm2. Eccentric compression test was performed to estimate the parameters, α, β1, γ for equivalent rectangular stress block. The ultimate moment strength ware obtained from the bending test on reinforced polymer concrete beams which were prepared with S different tensile steel ratios with a shear span ratio of 4.0. These values were compared with theoretical ultimate moment strengths, which were obtained using the parameters α=0.61 and β1=0.73 from stress-stain curves of C-shaped specimens. The results showed that, when tensile steel ratio was over 0.50 ρb, the experimentally obtained moment strengths were well matched with theoretically calculated values. In order to develop accurate criteria for polymer concrete flexural members, however, many other expermental studies for parameter determination are necessary using C-shaped specimens which have various compressive strengths and different sizes.

Diagnosis & Surgical Treatment of Neurilemmoma (신경초종의 진단과 수술적 치료)

  • Suh, Jeung-Tak;Park, Byung-Guk;Yoo, Chong-Il
    • The Journal of the Korean bone and joint tumor society
    • /
    • v.5 no.1
    • /
    • pp.44-50
    • /
    • 1999
  • Neurilemmoma is a benign encapsulated nerve sheath tumor originated from peripheral nerve. Previously its preoperative diagnosis had mainly depended on the history, physical examination, electrodiagnostic test, ultrasonography, bone scan. But only with these diagnostic modalities, exact preoperative diagnosis was nearly impossible. Therefore operation was performed under the impression of lipoma or just simple soft tissue tumor. Recently, the advent of magnetic resonance imaging(MRI) has made it easier to diagnose neurilemoma before surgery. MRI also helps to determine the extent of lesion and operative procedures. We performed marginal excision in 24 cases, evaluated those cases with respect to the sex, age, location, chief complaint, duration of illness, preoperative diagnosis, involved nerve, imaging studies, size of mass, complication, duration of follow-up and report with review of the literature.

  • PDF

Prediction of Cracking and Ultimate Loads of Prestressed Concrete Anchorage Zones in Box-Girder Bridges (프리스트레스트 콘크리트 박스거더 교량 부재의 정착부 균열하중 및 극한하중의 예측)

  • 임동환;오병환
    • Magazine of the Korea Concrete Institute
    • /
    • v.6 no.5
    • /
    • pp.171-182
    • /
    • 1994
  • Recently, several prestressed concrete box girder bridges have experienced severe cracking along the tendon path when prestress force has been transferred to the anchorage zone. The purpose of the present study is therefore to explore characteristics of the local stress distribution, to study the effects of section geometry of anchorage zones, i.e., tendon inclination, tendon eccentricity and concrett. cover thickness anti to develop recornrncnd;itions for specific design criteria for post~tensioned a:lchorage zones. 7'0 accomplish these objectives, a cc~mprehen sive nonlinar finite element study has been conducted. From this study, realistic forrnulas for crackinq and ultimate load capacities are proposed. 'These equations reasonably well predict the crackinq and ultimate loads of prestressed concrete anchorage zones.

Estimation of Physical Properties of Natural Gas Using Cubic Equations of State (3차형 상태방정식을 이용한 천연가스의 물성 추산)

  • Cho, Jung-Ho;Cho, Kyu-Sang;Kim, Dong-Hyeok;Lee, Young-Chul;Hong, Sung-Ho
    • Journal of the Korean Institute of Gas
    • /
    • v.10 no.4 s.33
    • /
    • pp.6-10
    • /
    • 2006
  • In this study, gross heating value(GHV), density, vapor pressure and heat capacity of natural gas were estimated and their experimental data were compared with calculated ones, SRK method. A new alpha function was used to predict the vapor pressures of pure component of the natural gas constituents well instead of calculating vapor pressures with acentric factors. And binary adjustable parameters were determined by regressing binary vapor-liquid equilibria data. Through this study, our results showed good agreements with experimental data.

  • PDF

Trevor's Disease; Dysplasia Epiphysealis Hemimelica - A Case Report - (Trevor 병; 편측성 골단 이형성증 - 증례 보고 -)

  • Kim, Hyoung-Soo;Chang, Jun-Hee
    • Journal of Korean Orthopaedic Sports Medicine
    • /
    • v.8 no.1
    • /
    • pp.60-63
    • /
    • 2009
  • Trevor's disease, also known as dysplasia epiphysealis hemimelica, is rare abnormality characterized by aberrant cartilaginous overgrowth forming one half of epiphysis. Typically the patient is 2 to 14 years of age. Until now only six cases, including a case recurred after surgery, have been reported in Korea. A seven year-old boy complained pain of the left knee. However, any deformity of the knee was not seen. The plain radiographic findings showed multiple ossifications asymmetrically on the medial epiphysis of distal femur. The magnetic resonance imaging (MRI) clearly demonstrated the epiphyseal mass which contained low signal spots corresponding to calcified foci and abnormal cartilaginous overgrowth. We report one additional case with a brief review of literature with the MRI findings.

  • PDF

Ultimate Strength Interaction of Steel/Concrete Composite Trapezoidal Box Girders Subjected to Concurrent Action of Bending and Torsion (휨과 비틀림을 동시에 받는 강/콘크리트 합성 제형 박스거더의 극한강도 상호작용)

  • Kim, Kyung-Sik
    • Journal of Korean Society of Steel Construction
    • /
    • v.22 no.5
    • /
    • pp.465-475
    • /
    • 2010
  • In the horizontally curved bridges, girders are subjected to the combined action of vertical bending and torsion due to their curvatures without any eccentric loads. As subjected to bending and torsion, the ultimate strength of steel/concrete composite box girders are limited by the diagonal tensile stress in the deck concrete induced by the St. Venant torsion. To determine the ultimate strength of composite box girders in bending and torsion and their interactions, this study conducted a 3-dimensional FEA and classical strength of materials investigation. Using ABAQUS, the FEA fully utilized advanced nonlinear analysis techniques simulating material/geometrical nonlinearity and post-cracking behaviors. The ultimate strength from numerical data were compared with theoretically derived values. Concurrent compressive stresses in the concrete deck improve the shear-resisting capacity of concrete, thereby resulting in an increased torsional resistance of the composite box girder in positive bending. The proposed interaction equation is very simple yet it provides a rational lower bound in determining the ultimate strength of concrete/steel composite box girders.

Study of Blood Characteristics in Stenosed Artery under Human Body Rotation by Using FSI Method (FSI 기법을 적용한 인체 회전 시 협착 혈관에서의 혈류 특성)

  • Cho, Seong Wook;Kim, Seungwook;Ro, Kyoung Chul;Ryou, Hong Sun
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.37 no.5
    • /
    • pp.449-457
    • /
    • 2013
  • In this study, we performed a numerical analysis to investigate the effect of rotation on the blood flow and arterial wall behavior by using the FSI (fluid-structure interaction) technique. The geometry of the artery included 50% stenosis at the center. To simulate the rotational effect, 2-6 rps of axial velocity was applied to the arterial model. A spiral wave and asymmetric flow occurred due to the stenosis and axial rotation both in the rigid body model and in the FSI model. However, the arterial wall motion caused periodic and transient blood flow changes in the FSI model. The FRZ (fluid recirculation zone) decreased in the FSI model, which is a known predictor for the formation and vulnerability of plaque. Therefore, it is observed that arterial wall motion also influences the generation of the FRZ.

Evaluation of Torsional Behaviour for the Catwalk System on A Suspension Bridge by Cross Bridge Interval (크로스 브릿지 간격에 따른 캣워크 시스템의 비틀림 거동 평가)

  • Lee, Ho;Kim, Ho Kyung;Kim, Gi Nam
    • Journal of Korean Society of Steel Construction
    • /
    • v.27 no.4
    • /
    • pp.371-376
    • /
    • 2015
  • This study was conducted for the torsional behavior of catwalk system which is a temporary structure on a suspension bridge. The torsional deformation of the catwalk structure has a significant effect on the workability and safety of workers during main cable erection. For this reason, the torsional deformation of catwalk is controlled to be acceptable levels below by adjusting the cross bridge interval in design stage. This study analyzed the effect of separation between cross bridge associated with twist safety of catwalk system. For the analytical approach, a detailed analysis model was created including cross bridge. Both wind load within the wind velocity range that allows the construction and eccentric load of Prefabricated Parallel Wire Strand were analyzed by analysis model. Result of study shows that separation between cross bridges has a significant effect on the torsional behavior of the catwalk.

Evaluation of Flexural Behavior of a Modular Pier with Circular CFT (충전원형강관을 이용한 모듈러 교각의 휨 거동 평가)

  • Ma, Hyang Wook;Oh, Hyun Chul;Kim, Dong Wook;Kong, Davon;Shim, Chang Su
    • Journal of Korean Society of Steel Construction
    • /
    • v.24 no.6
    • /
    • pp.725-734
    • /
    • 2012
  • A new modular pier system using concrete filled circular steel tubes was suggested to realize modular bridge substructures for accelerated bridge construction. Structural details and connection details were proposed by connection multiple concrete filled tubes (CFT) for standardized products of fabrication, delivery and erection. Static tests were performed for the modular pier with suggested details under lateral load conditions for weak and strong axes. Due to the eccentricity by the bracing system, the modular pier showed 5.23 times higher flexural stiffness and 6 times greater flexural strength from the test. It is proper for the rational design to evaluate stress and deformation by frame modeling of the modular CFT pier. Structural capacity of the pier can be obtained by adjusting the spacing of the CFT columns. Design recommendations were derived from the test.