• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.6
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• pp.399-405
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• 2023

This study presents an optimal seismic design method based on genetic algorithms to induce beam-hinge collapse mechanisms in reinforced concrete moment frames. Two objective functions are used. The first minimizes the cost of the structure and the second maximizes the energy dissipation capacity of the structure. Constraints include strength conditions of columns and beams, minimum conditions for column-to-beam flexural strength ratio, and conditions for preventing plastic hinge occurrence of columns. Linear static analysis is performed to evaluate the strength of members, whereas nonlinear static analysis is carried out to evaluate energy dissipation capacity and occurrence of plastic hinges. The proposed method was applied to a four-story example structure, and it was confirmed that solutions for inducing a beam-hinge collapse mechanism are obtained. The value of the column-beam flexural strength ratio of the obtained design was found to be larger than the value suggested by existing seismic codes. A more robust strategy is needed to induce a beam-hinge collapse mode.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.353-362
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• 2015

Cyclic loading tests for the PC moment frame with plastic shear hinges were performed to evaluate the seismic performance. The plastic shear hinges consisted of two steel plates were installed at the mid-length of the beam to connect the PC frames. Three shear links are existed in each steel plate. The three shear links were designed using shear force corresponding to the shear capacity of 50%, 75%, and 100% of the beam shear capacity. The proposed connections showed an efficient energy dissipation capacity and good structural performance. As a result, it is reasonable to design the plastic shear hinges using design shear capacity less than 100% of the beam shear capacity.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.33-44
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• 2003

This paper describes the design and analysis technology of composite flexure and composite paddle-type blade which are all key technologies on hingeless rotor system. Through replacing the existing metal or engineering plastic flexure part with composite part, Several required structural analysis were accomplished, which are static analysis by using NASTRAN and dynamic analysis by using FLIGHTLAB. The dynamic characteristics of composite hingeless hub attached with paddle-type blade was also investigated. Further more, small-scaled paddle-type blade was designed using froude scaled properties of existing full size blade. Through this design procedure of composite paddle-type blade, the structural design method was achieved. These results will be applied to accomplishing current project named as "the development of next-generation helicopter rotor system."

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.887-895
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• 2017

This paper presents a study on the accelerated life tests of parts that operate during the opening and closing of door frames, particularly door hinges. Hinge theoretical verification and validation of the test equipment in the present study and the different structures and fault mode, depending on the purpose of usage analysis, failure mode for one of the hinges of the switchgear components used for electromagnetic shielding facilities and on-site operating conditions. The accelerated life test was designed for the characteristic lifetime prediction of the components, by estimating the shape parameter and the acceleration factor.

• Composites Research
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• v.22 no.6
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• pp.7-12
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• 2009

This paper deals with a fabrication method of composite hinge mechanisms for flapping-wing micro air vehicles. The fabrication process includes curing process of Graphite/Epoxyprepregs, laser cutting for high fabrication repeatability, laminating of Graphite/Epoxy prepregs with Kapton film which is used for flexure, and so on. The fabricated hinge mechanism was attached with PUMPS actuators and the measured flapping angle was $173^{\circ}$ when driving voltage was 300V 170Hz.

• Computational Structural Engineering
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• v.11 no.4
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• pp.295-307
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• 1998

철근콘크리트 보에 대해서 인장강화효과의 소성힌지길이를 고려한 재료비선형 해석을 수행하였다. 비선형 해석에서 자유도가 많은 대형구조물에 적용시키기에는 많은 제약이 따르는 복잡한 층상해석기법을 사용하는 대신 단면해석을 통해 미리 구성된 모멘트-곡률 관계를 이용하였으며, 유한요소해석에서 사용요소의 크기에 따른 수치해석상의 오차를 줄이기 위해 인장강화효과와 소성힌지길이 개념을 도입하였다. 마지막으로 제안된 해석 알고리즘의 타당성을 검증하기 위하여 해석결과와 실험결과간의 상호 관계를 비교, 분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.253-260
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• 2016

In this paper, the optimal seismic design method for inducing the beam-hinge collapse mechanism of steel moment frames is presented. This uses the non-dominated sorting genetic algorithm II(NSGA-II) as an optimal algorithm. The constraint condition for preventing the occurrence of plastic hinges at columns is used to induce the beam-hinge collapse mechanism. This method uses two objective functions to minimize the structural weight and maximize the dissipated energy. The proposed method is verified by the application to nine story steel moment frame example. The minimum column-to-beam strength ratio to induce the beam-hinge collapse mechanism are investigated based on the simulation results. To identify the influence of panel zone on the minimum column-to-beam strength ratio, three analytic modeling methods(nonlinear centerline model without rigid end offsets, nonlinear centerline model with rigid end offsets, nonlinear model with panel zones) are used.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.97-100
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• 2008

Subjected to seismic action causing large deformation of bridge columns, the plastic hinge region is commonly formed in the column end zone. The deformation capacity of a concrete column can be expressed by using plastic hinge length. The mechanical properties of high-strength reinforcing steel is different from that of normal-strength steel and the mechanical properties of steel will influence the plastic hinge formation. Therefore, in other to accurately predict the deformation of concrete column using high-strength steel, the plastic hinge length can be expressed as a function of the mechanical properties of steel such as the tensile to yield strength ratio and the strain at ultimate state. However, little research has been conducted into the effect of mechanical properties of steel on the plastic hinge length. It was difficult to measure the plastic hinge length from the test results. Therefore, the plastic hinge length of concrete columns was investigated from the curvature profile. A numerical approach was used to study the effect of various parameters on plastic hinge length. Based on the results of the numerical parametric study, a new expression for plastic hinge length was proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.117-126
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• 2002

In this paper, 3-D fame design using second-orders plastic-hinge analysis accounting for lateral torsional buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional second-order plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by lateral torsional buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the unbraced length and cross-section shape is used to account for lateral torsional buckling. The proposed analysis is verified by the comparison of the LRFD results. A case studs shows that lateral torsional buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient reliable tool ready to be implemented into design practice.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.13-21
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• 2002

In this paper, 3-D frame design using refined plastic-hinge analysis accounting for local buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional refined plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by local buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the width-thickness ratio is used to account for local buckling. The proposed analysis is verified by the comparison of the LRFD results. A case study shows that local buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient, reliable tool ready to be implemented into design practice.