• Title/Summary/Keyword: 모멘트분석

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Evaluation of Ductility and Strength Factors for Special Steel Moment Resisting Frames (철골 연성 모멘트 골조의 연성계수 및 강도계수 평가)

  • Kang, Cheol Kyu;Choi, Byong Jeong
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6 s.73
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    • pp.793-805
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    • 2004
  • The main objective of this paper is to evaluate the ductility and strength factors that are key components of the response modification factor for special steel moment-resistant frames. The ductility factors for special steel moment-resistant frames were calculated by multiplying the ductility factor for SDOF systems and the MDOF modification factors. Ductility factors were computed for elastic and perfectly plastic SDOF systems undergoing different levels of inelastic deformation and periods when subjected to a large number of recorded earthquake ground motions. Based on the results of the regression analysis, simplified expressions were proposed to compute the ductility factors. Based on previous studies, the MDOF modification factors were also proposed to account for the MDOF systems. Strength factors for special steel moment resisting frames were estimated from the results of the nonlinear static analysis. A total of 36 sample steel frames were designed to investigate the ductility and strength factors considering design parameters such as number of stories (4, 8, and 16 stories), seismic zone factors (Z = 0.075, 0.2, and 0.4), framing system (Perimeter Frames, PF and Distributed Frames, DF), and failure mechanism (Strong-Column Weak Beam, SCWB, and Weak-Column Strong-Beam, WCSB). The effects of these design parameters on the ductility and strength factors for special steel moment-resisting frames were investigated.

Flexural Strength of Composite HSB Girders in Positive Moment (HSB 강합성거더 정모멘트부의 휨저항강도)

  • Cho, Eun-Young;Shin, Dong-Ku
    • Journal of Korean Society of Steel Construction
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    • v.22 no.4
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    • pp.389-398
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    • 2010
  • The flexural strength of composite HSB I-girders under a positive moment was investigated using the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specifications to such girders. A total of 2,391 composite I-girder sections that satisfied the section proportion limits of the AASHTO LRFD specifications was generated by the random sampling technique to consider a wide range of section properties. The flexural capacities of the sections were calculated inthe nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels were modeled as an elasto-plastic strain-hardening material, and the concrete, as a CEB-FIP model. The effects of the ductility ratio and the compressive strength of the concrete slab on the flexural strength of the composite girders made of HSB and SM520-TMC steels were analyzed. The numerical results indicated that the current AASHTO LRFD equation can be used to calculate the flexural strength of composite girders made of HSB600 steel. In contrast, the current AASHTO LRFD equation was found to be non-conservative in its prediction of the flexural strength of composite HSB800 girders. Based on the numerical results of this study for 2,391 girders, a new design equation for the flexural strength of composite HSB800 girders in a positive moment was proposed.

Evaluation of the Moment Bearing Capacity of Offshore Bucket Platforms in Sand (사질토 지반에 설치된 해상 버켓작업대의 모멘트 지지력 산정)

  • Vicent, Ssenyondo;Gu, Kyo-Young;Kim, Sung-Ryul
    • Journal of the Korean Geotechnical Society
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    • v.35 no.12
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    • pp.101-109
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    • 2019
  • The bucket platform is a new structure suitable for construction of offshore bridge foundations and providing the temporary support for equipments and labour. The platform can be subjected to moment loading due to the eccentric loading or the horizontal load by wave and wind. Therefore, a three dimensional finite element analysis was performed to evaluate the moment bearing capacity of the bucket platform, varying soil density, the diameter and embedment depth of the bucket. The numerical modeling was verified and compared with the moment-rotation curve from a field loading test. The uniform sandy ground was assumed and the moment load was applied at the top plate of the platform, increasing bucket rotation. The moment-rotation relations were analyzed to determine the moment capacity, which was influenced by the embedment depth and diameter of the bucket. Finally, a preliminary design equation was suggested to estimate the moment bearing capacity.

An Analytical Study on the Nonlinear Behavior of Double Angle Connections Subjected to Shear (전단력을 받는 더블 앵글 접합부의 비선형 거동에 관한 해석적 연구)

  • Lee, Soo-Kueon;Hong, Kap-Pyo
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1 s.44
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    • pp.65-73
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    • 2000
  • The behavior of double angle connections is analyzed by 3D finite element method using ABAQUS(ver 5.8). Moment-rotation curves for the connections are generated, as well as stress distribution for angle and bolt. Double angle connections have various angle thickness, gage distance and number of bolt. Parameters, such as initial stiffness, plastic tiffness, reference load and curve shape parameter were obtained by regression method using Richard's formula. These parameter lead to predict nonlinear behavior of double angle connection. Design curves giving the parameters of the moment-rotation curves are generated. These parameters are primarily a function of the angle thickness, gage distance and the number of bolts in the connection. Using these parameters, connection moment and its ratio to the full plastic moment capacity Mp of the beam are calculated.

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Flexural Strength of Composite HSB Hybrid Girders in Positive Moment (HSB 강재 적용 강합성 복합단면 거더 정모멘트부의 휨저항강도)

  • Cho, Eun-Young;Shin, Dong-Ku
    • Journal of Korean Society of Steel Construction
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    • v.23 no.3
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    • pp.385-395
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    • 2011
  • The flexural strength of composite HSB hybrid I-girders under positive moment is investigated by the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specification to such girders. The hybrid girders are assumed to have the top flange and the web fabricated from HSB600 steel and the bottom flange made of HSB800 steel. More than 6,200-composite I-girder sections that satisfy the section proportion limits of AASHTOL RFD specifications are generatedby the random sampling technique to consider a statistically meaningful wide range of section properties. The flexural capacities of the sections are calculated by the nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels are modeled as an elastoplastic, strain-hardening material and the concrete as CEB-FIP model. The effects of ductility ratio and compressive strength of concrete slab on the flexural strength of composite hybrid girders make of HSB steels are analyzed. Numerical results indicated that the current AASHTO-LRFD equation can be used to calculate the flexural strength of composite hybrid girders fabricated from HSB steel.

The Study on Experimental Measurement Method of Hinge Moment Acting on Control Surface of Air Vehicle (비행체 조종면에 작용하는 힌지 모멘트의 시험적 측정 방법 연구)

  • Park, Jong-Min;Chung, Sang-Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.2
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    • pp.165-170
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    • 2012
  • This paper contains the test method to obtain aerodynamic hinge moments acting on the control surface of air vehicle wing. During the flight, hinge moments make difference between actual control surface angle and control angle which is measured by sensor of actuator. The hinge moments can be obtained by using this difference. Static ground load test and calibration test were conducted to obtain torsional stiffness of control surface actuation system. This results are used to calculate hinge moments. In addition, the mechanical errors of actuation system such as slip angle of mounting point and backlash could be estimated. Using flight test results, this experimental measurement method of hinge moment acting on control surface is conducted. The results of this method are similar to those of numerical simulation method, and the validity of this method is proved.

Design Method of RC Flat Plate Slab Considering Unbalanced Moment (불균형모멘트를 고려한 RC 무량판 슬래브 설계방법)

  • Song, Jin-Kyu;Sing, Ho-Beom;Oh, Sang-Won;Han, Sun-Ae
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.149-152
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    • 2008
  • In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress of direct shear occurred by balanced gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. For this problem, a model to show unbalanced moment-punching shear interrelation was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment-punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, a effective width enlargement factor for deciding the unbalanced moment strength of flat plates with shear reinforcements was proposed. The interrelation model proposed in this paper is very effective for the design because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.

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Experimental Study on the Influence of Moment Distribution Shape on the Effective Moment of Inertia of Simply Supported (모멘트 분포 형상에 따른 철근콘크리트 단순보의 유효 단면2차모멘트에 대한 실험적 연구)

  • Park, Mi-Young;Lee, Seung-Bae;Kim, Kang-Su;Kim, Sang-Sik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.329-332
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    • 2008
  • The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete structures, and the concept of the effective moment of inertia has been generally used for the estimation of beam deflections. The KCI design code adopted Branson's equation for the calculation of the effective moment of inertia, which was formulated based on the results of beam tests subjected to uniformly distributed loads. Therefore, it is worthwhile to check the applicability of the code approach on the estimation of the effective moment of inertia for the cases of beams under different loading conditions. In this study, an experimental investigation has been conducted on six beams, where primary variables were concrete compressive strengths and loading distances from supports. The test results were compared with various approaches proposed by Branson and others as well. The test results indicated that the effective moment of inertia was somewhat influenced by the moment distribution shape. Despite the different moment distribution shapes for specimens, however, the effective moment of inertia of all test beams were closely predicted by the existing methods considered in this study.

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Seismic Moment Conversion of instrumented Earthquakes in and around the Korean Peninsula (Ⅰ):from$m_b$or$m_s$to$m_0$ (한반도 및 인근 지역 계기지진의 지진모멘트 환산(Ⅰ):$m_b$또는 $m_s$에서$m_0$)

  • No, Myeong-Hyeon;Lee, Sang-Guk;Choe, Gang-Ryong
    • Journal of the Korean Geophysical Society
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    • v.4 no.1
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    • pp.47-55
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    • 2001
  • conversion equations to calculate seismic moment(M_0) from body-wave magnitude(m_b), surface-wave magnitude(M_s), or both were derived by using 50 earthquakes occurred within 32~44°N and 123~133°E whose M_0 were determined together with m_b or M_s. We divided those earthquakes into the deeper and the shallower ones based on the reference focal depth of 70 km. The unit of M_0 is dyne-cm. In case of M_s, the deeper earthquakes exhibit the higher seismic moment than the shallower ones. Standard deviations associated with conversion equations for deeper and shallower earthquakes are 0.25 and 0.16, respectively, in moment magnitude. , for deeper earthquakes , for shallower earthquakes. In case of m_b, the dependence of conversion equation on focal depth is not clearly observed. Associated standard deviation is 0.28 in moment magnitude. In case that both m_b and M_s were determined, a new magnitude, , were defined for shallower earthquakes to derive a more stable conversion equation. Associated standard deviation is 0.14 in moment magnitude. Conversion equations above can be used to unify the earthquake size into a single magnitude type, i.e., moment magnitude, in and around the Korea Peninsula.

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Independent Component Analysis Based on Neural Networks Using Hybrid Fixed-Point Algorithm (조합형 고정점 알고리즘에 의한 신경망 기반 독립성분분석)

  • Cho, Yong-Hyun
    • The KIPS Transactions:PartB
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    • v.9B no.5
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    • pp.643-652
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    • 2002
  • This paper proposes an efficient hybrid fixed-point (FP) algorithm for improving performances of the independent component analysis (ICA) based on neural networks. The proposed algorithm is the FP algorithm based on secant method and momentum for ICA. Secant method is applied to improve the separation performance by simplifying the computation process for estimating the root of objective function, which is to minimize the mutual informations of the independent components. The momentum is applied for high-speed convergence by restraining the oscillation if the process of converging to the optimal solution. It can simultaneously achieve a superior properties of the secant method and the momentum. The proposed algorithm has been applied to the composite fingerprints and the images generated by random mixing matrix in the 8 fingerprints of $256\times{256}$-pixel and the 10 images of $512\times{512}$-pixel, respectively. The simulation results show that the proposed algorithm has better performances of the separation speed and rate than those using the FP algorithm based on Newton and secant method. Especially, the secant FP algorithm can be solved the separating performances depending on initial points settings and the nonrealistic learning time for separating the large size images by using the Newton FP algorithm.