• 한국안전학회지
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• 제33권4호
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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.

• 한국지진공학회논문집
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• 제22권6호
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• pp.353-360
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• 2018

This paper is to investigate the micro-behavior of the double-span beams with WUF-W seismic connection under combined axial tension and moment and to propose the rational rotational capacity of it for progressive collapse-resistant analysis and design addressing the stress and strain transfer mechanism. To this end, the behavior of the double-span beams under the column missing event is first investigated using the advanced nonlinear finite element analysis. The characteristics of fracture indices of double-span beams with WUF-W connection under combined axial tension and flexural moment are addressed and then proposed the rational rotational capacity as the basic datum for the progressive collapse-resistant design and analysis. The distribution of fracture indices related to stress and strain for the double-span beams is investigated based on a material and geometric nonlinear finite element analysis. Furthermore, the micro-behavior for earthquake and progressive collapse is explicitly different.

• Steel and Composite Structures
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• 제14권6호
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• pp.621-636
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• 2013

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake, in conformity with the point that many seismic design codes led to reduce the loads. In the present paper it's tried to evaluate the response modification factors of dual moment resistant frame with buckling restrained braced (BRB). Since, the response modification factor depends on ductility and overstrength; the nonlinear static analysis, nonlinear dynamic analysis and linear dynamic analysis have been done on building models including multi-floors and different brace configurations (chevron V, invert V, diagonal and X bracing). The response modification factor for each of the BRBF dual systems has been determined separately, and the tentative value of 10.47 has been suggested for allowable stress design method. It is also included that the ductility, overstrength and response modification factors for all of the models were decreased when the height of the building was increased.

• 한국작물학회지
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• 제11권
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• pp.105-117
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• 1972

본연구는 맥류의 도복에 관여하는 주요형질의 상호관계를 구명함과 아울러 주요 대소맥 품종의 내도복성정도를 분류하고, 내도복성 품종 선발의 기준을 인정하여 보고자 한 것이며, 그 결과를 요약하면 다음과 같다. 1. 포장도복과 도복지수는 고도의 정의 상관(대맥 r=0.44-0.67 소맥 r=0.46-0.68)이 있으며 지상부 Bending moment에 간자체의 정도를 가미한 지수로서 도복저항성 검정에 가장 유효하다. 2. 간의 Bending stiffness를 표시하는 좌절시 Bending moment와 단면 2차 moment와는 정의 높은 상관(대백 r=0.59, 소맥 r=0.46-0.53)을 보였다. 3. 간의 Bending stiffness(좌절시 Bending moment 단면 2차 moment)와 간에의 건물집적량을 표시하는 단위간건물중과는 높은 정의 상관 (대맥 r=0.35-1.40, 소맥 r=0.33-0.76)을 보였다. 4. 도복지수와 단위간건물중 (대맥 r=-0.51～-0.70, 소맥 r=-0.65～-0.83) 좌절시 Bending moment (대맥 r=-0.29～-0.69, 소맥 r=-0.54～-0.89)과는 특히 높은 부의 상관을 보였으며, 소맥의 경우는 좌절하중, 단면 2차 moment, 단면계수와는 높은 부의 상관을 보였다. 5. 간외경은 간내경보다 간의 물리적 특성과 상관이 높으며 좌절하중 (대맥 r=0.42-0.56, 소맥 r=0.39-0.44), 좌절시 Bending moment (대맥 r=0.40-0.41, 소맥 r=0.38-0.49), 단면 2차 moment (대맥 r=0.56-0.97, 소맥 r=0.0.28-0.28), 단면계수(소맥 r=0.22-0.96)와는 정의 높은 상관이 있었고, 간벽후와 물리적특성과도 정의 상관을 보였다. 6. 간장은 포장도복과는 품종군에 따라서는 정의 상관은 보이나, 간의 강도를 고려한다면 내도복저항성품종 선발의 지표로서 이용하기는 어려울 것으로 보인다. 7. 대소맥의 많은 품종의 내도복성 정도를 분류한 결과, 한국품종중 대맥은 내도복저항성품종이 많고, 대맥은 내도복성인 품종의 분포가 대맥보다 적었으나, 일본품종들을 대소맥 모두 내도복저항성인 품종이 많았다. 8. 내도복저항성인 품종의 선발을 위하여는 도복지수가 대맥 1.67 소맥 1.76 정도 이하인 것은 고도의 저항성이 있었다.

• 콘크리트학회논문집
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• 제16권3호
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• pp.335-344
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• 2004

이 논문에서는 프리캐스트 콘크리트와 현장타설 콘크리트 그리고 긴장된 강재와 긴장되지 않은 강재 등으로 구성되는 합성단면에서 콘크리트 장기변형의 내부구속에 의한 잔류응력과 긴장력 손실을 해석하였다. 이 해석결과로부터 사용 중에 도입되는 추가 긴장력으로 합성거더를 보강하는 경우에 필요한 추가 긴장력의 설계식과 저항모멘트 평가식이 제안되었다. 제안된 식은 일차 긴장력의 손실률이 설계규준의 일괄손실 등에 의해 과대평가되는 경우에 허용응력으로부터 결정되는 추가 긴장력 또한 과대평가 될 수 있음을 보여준다. 일반적으로 많이 사용되는 AASHTO Type 5 거더의 합성단면에 대해 이 논문의 해석방법을 적용 및 검토하였다. 프리캐스트 콘크리트 거더에 추가 긴장력이 도입되는 경우 일차 긴장력과 추가 긴장력의 손실률은 합성거더에 도입되는 경우보다 작았으나, 저항모멘트는 합성거더에 추가 긴장력이 도입되는 경우 상당히 증가하였다. 합성거더에 도입된 추가 긴장력의 보강효과는 매우 우수하였다.

• Structural Engineering and Mechanics
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• 제1권1호
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• pp.31-46
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• 1993

The motivations of the application of shakedown analysis to the earthquake-resistant design of ductile moment-resisting steel structures are presented. The problems which must be solved with this application are also addressed. The illustrative results from a series of static and time history nonlinear analyses of one-bay three-story steel frame and the related discussions have shown that the incremental collapse may be the critical design criterion in case of earthquake loading. Based on the findings, it was concluded that the inelastic excursion mechanism for alternation load pattern, such as in earthquake, should be the sidesway mechanism of the whole structure for the efficient mobilization of the structural energy dissipating capacity and that the shakedown analysis technique can be used as a tool to ensure this mechanism.

• 한국가구학회지
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• 제24권4호
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• pp.444-451
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• 2013

In this paper, experimental results were presented on the moment resistance of a concealed timber post base joint aimed at replacing in a modern design introduced lately the wood to wood joints used in the traditional Korean timber house - Hanok. Preliminary results showed that the original configuration of the joint offers a limited moment resistance and a low ductility and energy dissipation. In an attempt to mitigate those limitations without undergoing major changes in the connector, three new configurations were proposed and investigated. Motivated by the wish to prevent the early failure in welds, a first approach consists in directly bolting the connector's upper plate to lower the stress on the weak welds. Alternatively, another approach focused on increasing the strength of these welds by extending their length to the full width of the metal wings. Finally, a third configuration investigated the effect of those two approaches combined. In conclusion, reinforcing the welds found out to be the best option among the presented ones. As a result, this connector considered to show proper ability for use in earthquake-resistant structures with suited lateral-resistant structural elements.

• 한국농공학회지
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• 제43권6호
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• pp.113-119
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• 2001

Experiments on the yield strength of pipe connectors made of metal wire, joint pins, pole pipes, multi span insertion joints, and T-clamp joints used in pipe houses were conducted. The strength of connections of a pipe connector made of metal wire was adequate but it had a big difference according to loading direction. Therefore as it is installed, its direction should be taken into consideration. The collapse load of pipes connected with a joint pin was lower than that of single pipes. In the part of frame member at which the great bending moment occurs, the use of joint pin should be avoided. Also experimental results showed that pole pipes for use in a part of frame buried under the ground were safe, and the strength of multi span insertion joints should be increased. The resistant moment of T-clamp was about 13.7% of a single pipe. In case that the external forces acting on left and right rafter are different. a unsymmetrical rotational force is produced at the multi span joint. If it is expected that the actual bending moment on the multi span joint is larger than resistant moment of T-clamp, a reinforcement to safely resist the rotational force is required.

• International Journal of Concrete Structures and Materials
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• 제8권1호
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• pp.1-14
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• 2014

In the present paper, a behavioral model is proposed for study of the individual contributions to shear capacity in shear-critical reinforced concrete members. On the basis of the relationship between shear and bending moment (V = dM/dx) in beams subjected to combined shear and moment loads, the shear resistant mechanism is explicitly decoupled into the base components-beam action and arch action. Then the overall behavior of a beam is explained in terms of the combination of these two base components. The gross compatibility condition between the deformations associated with the two actions is formulated utilizing the truss idealization together with some approximations. From this compatibility condition, the ratio of the shear contribution by the tied arch action is determined. The performance of the model is examined by a comparison with the experimental data in literatures. The results show that the proposed model can explain beam shear behavior in consistent way with clear physical significance.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2018년도 추계학술대회
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• pp.87-89
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• 2018

We proposed an improved reliable SVD-based watermarking scheme resistant to geometric attacks while having high fidelity with no false-positive problem. Principal components of a watermark image are embedded into singular values of LL, LH, HL, and HH sub-bands of a transformed cover image by RDWT(redundant discrete wavelet transform) with optimal scale factors. Each scale factor is generated by trading-off fidelity and robustness using Differential Evolution (DE) algorithm. Zernike Moment (ZM) is used to estimate the geometric distortion and to correct the watermarked image before extracting watermark. The proposed scheme improves fidelity and robustness of existing reliable SVD based watermarking schemes while resisting to geometric attacks.