• Title/Summary/Keyword: Horizontal Members

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Flexural Strength and Rotational Stiffness Estimation of Joint between Vertical and Horizontal Members in System Support (시스템 동바리 수직재와 수평재 연결부의 휨강도와 회전 강성 평가)

  • Won, Jeong-Hun;Lee, Hyung Do;Choi, Myeong-Ki;Park, Man Cheol
    • Journal of the Korean Society of Safety
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    • v.33 no.4
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    • pp.46-53
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    • 2018
  • This study examined the maximum resistant moment and nonlinear rotational stiffness of wedge joint between the vertical and horizontal members of system supports. To examine the maximum resistant moment and propose the nonlinear rotation stiffness of wedge joint, 6 specimens were tested and additional 3 specimens, where the horizontal member was welded to the vertical member, were tested to compare the moment capacity of wedge joints. The average maximum moment in the tested wedge joint was 1.183 kNm which represented about 70 % of the maximum moment developed in the welded specimens. And, as simulating nonlinear rotational stiffness of the wedge joint, a tri-linear model was suggested. The rotational stiffness was estimated as 23.095 kNm/rad in first stage, 7.945 kNm/rad in second stage, and 3.073 kNm/rad in third stage. For the failure mode, the specimen with the wedge joint showed the failure of joint between vertical and horizontal members. However, the specimen with welded joint represented the yielding of horizontal members.

Reliability Analysis of Three-Dimensional Temporary Shoring Structures Considering Bracing Member and Member Connection Condition (가새재 및 부재 연결 조건을 고려한 3차원 가설 동바리 구조물의 신뢰성 해석)

  • Ryu, Seon-Ho;Ok, Seung-Yong;Kim, Seung-Min
    • Journal of the Korean Society of Safety
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    • v.34 no.1
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    • pp.53-61
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    • 2019
  • This study performs reliability analysis of three-dimensional temporary shoring structures with three different models. The first model represents a field model which does not have diagonal bracing members. The installation of bracing members is often neglected in the field for convenience. The second model corresponds to a design model which has the bracing members with the hinge connection of horizontal and bracing members at joints. The third model is similar to the second model but the hinge connection is replaced with partial rotational stiffness. The reliability analysis results revealed that the vertical members of the three models are safe enough in terms of axial force, but the vertical and horizontal members exhibit a big difference among the three models in terms of combination stress of axial force and bi-axial bending moments. The field model showed significant increase in failure probability for the horizontal member, and thus the results demonstrate that the bracing member should be installed necessarily for the safety of the temporary shoring structures.

CFRP strengthening of steel beam curved in plan

  • Keykha, Amir Hamzeh
    • Steel and Composite Structures
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    • v.41 no.5
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    • pp.637-648
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    • 2021
  • Nowadays, one of the practical, fast and easy ways to strengthen steel elements is the use of Carbon Fiber Reinforced Polymer (CFRP). Most previous research in the CFRP strengthening of steel members has carried out on straight steel members. The main difference between horizontal curved beams and straight beams under vertical load is the presence of torsional moment in the horizontal curved beams. In the other words, the horizontal curved beams are analyzed and designed for simultaneous internal forces included bending moment, torsional moment, and shear force. The horizontal curved steel beams are usually used in buildings, bridges, trusses, and others. This study explored the effect of the CFRP strengthening on the behavior of the horizontal curved square hollow section (SHS) steel beams. Four specimens were analyzed, one non-strengthened curved steel beam as a control column and three horizontal curved steel beams strengthened using CFRP sheets (under concentrated load and uniform distributed load). To analyze the horizontal curved steel beams, three dimensional (3D) modeling and nonlinear static analysis methods using ANSYS software were applied. The results indicated that application of CFRP sheets in some specific locations of the horizontal curved steel beams could increase the ultimate capacity of these beams, significantly. Also, the results indicated when the horizontal curved steel beams were under distributed load, the increase rate in the ultimate capacity was more than in the case when these beams were under concentrated load.

Structural Behavior Analysis of System Supports according to Boundary Condition of Joints between Vertical and Horizontal Members (시스템 동바리의 수직재와 수평재 연결부 경계조건에 따른 거동 분석)

  • Kim, Gyeoung Yun;Won, Jeong-Hun;Kim, Sang-Hyo
    • Journal of the Korean Society of Safety
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    • v.32 no.3
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    • pp.60-65
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    • 2017
  • This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.

The Effect of Secondary Members on the Behavior of Steel-Concrete Composite Two-Girder Railway Bridges (2거더 강-콘크리트 합성형 철도교의 거동에 대한 2차부재의 영향 평가)

  • Bae Doo-byong;Cho Joon-hee
    • Journal of the Korean Society for Railway
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    • v.8 no.1
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    • pp.41-50
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    • 2005
  • Steel -Concrete Composite two girder railway bridges applying high performance steel with extra thick plate have economic and aesthetic advantages due to the simplification of manufacturing and construction process. However, steel bridges are seldom adopted in domestic railway bridge, since steel bridges are not efficient as R.C bridges considering dynamic characteristics and noise, etc. While highway bridges do not have lower horizontal bracing and larger interval of diaphragm cross beam, railway bridges install lower horizontal bracings to control the torsion due to heavy eccentrical line load. Accurate finite element analysis were performed with the parameters of existence of bracing and bracing shape, with the cross beam interval and stiffness, etc. To find out the effects of secondary members such as horizontal bracings and diaphragms, static md dynamic analysis have been performed by using finite element method. In this study, few member plate-girder bridges are analyzed with variable span lengths to examine the dynamic behavior and limits of damping. And though lateral bracings are members against torsion, but lateral bracing's absence is no big problem. Time history analysis using mode superposition method makes proof of this result.

A Study on the Location of Supporting Members in Monoleaflet Polymer Valve to Minimize Stress and Deformation (응력과 변형을 최소화하기 위한 단엽식 고분자 판막의 지지대 위치에 관한 연구)

  • Lee Seong Wook;Shim Jae Joon;Han Dong Seop;Han Geun Jo;Kim Tae Hyung
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.2
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    • pp.156-163
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    • 2005
  • A monoleaflet polymer artificial heart valve showed the remarkable improvement in pressure drop compared with other types of artificial valve. So, in this study we designed a monoleaflet polymer artificial valve with two supporting members to minimize the deformation and bending stress of the valve with respect to the variation of the gap between two supporting members using nonlinear contact analysis. The marginal valve thickness was also predicted in accordance with the relationship between the thickness and horizontal displacement in order to prevent the dislocation of the valve tip from the frame wall.

A Study on the Effect of Construction Time in the Column Shortening in High-Rise Building (초고층 구조물에서 기둥축소에 대한 시공기간의 영향에 관한 연구)

  • 정은호;김희철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1996.10a
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    • pp.267-274
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    • 1996
  • Differential shortening of vertical members in high-rise buildings affect other structural members that have to be considered such as horizontal members and exterior cladding. of many elements which affect the total amount of shortening, different loading history mainly comes from the different construction time. Shortening of 66 story concrete columns were investigated and compared according to the different construction time, little difference was found between the total shortening of interior and that of exterior column.

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Nonlinear Analysis of the Monoleaflet Polymer Valve According to Shape of Supporting Members (지지대 형상에 따른 단엽식 고분자 판막의 비선형 해석)

  • 한근조;안성찬;심재준;김성윤
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.748-751
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    • 2001
  • Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation monoleaflet the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members straight member, and two curved members was analysed using the large deformation nonlinear finite element method.

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Nonlinear Analysis of the Monoleaflet Polymer Valve according to Shape of Supporting Members (지지대 형상에 따른 단엽식 고분자 판막의 비선형 해석)

  • 한근조;안성찬;심재준;김성윤
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.3
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    • pp.120-124
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    • 2003
  • Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation of monoleaflet heart valve the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members, straight member and two curved members were analysed using the large deformation nonlinear finite element method.

Effects of Number of bays and Bracing Member on the Ultimate Behavior of System Scaffolds (Bay 수와 가새재 설치가 시스템 비계 극한거동에 미치는 영향)

  • Lee, Sun-Woo;Jang, Nam-Kwon;Won, Jeong-Hun;Jeong, Seong-choon
    • Journal of the Korean Society of Safety
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    • v.35 no.3
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    • pp.6-15
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    • 2020
  • This study examined the structural behaviors and ultimate loads of assembled system scaffolds by load tests. Considering the number of bay and bracing installation, four specimens were tested. The bays were divided into 1 bay and 2 bays, with and without the bracing member installed. Failure modes and horizontal displacements show that the whole column buckled without showing no point of inflection in the column, regardless of whether or not braces were installed. Thus, the current design method of selecting the vertical spacing between the horizontal members of the system scaffold as the effective buckling length underestimates the effective buckling length. In case of 1 bay specimens, the ultimate loads between specimens with and with bracing members are similar. However, in case of 2 bay specimens, the specimen with bracing members shows the increased ultimate load of 36% compared with that without bracing members. In addition, as the number of bays in the system scaffold increases, the ultimate load of the unit vertical column increases in case of the specimen with bracing installation. However, in the specimen without bracing members, the ultimate load of the unit column reduces with the increment of the number of bays due to the torsional buckling. Therefore, it is essential to install bracing members to increase the whole strength of system scaffolds and the ultimate load of the unit column.