• 한국지진공학회논문집
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• 제1권3호
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• pp.21-27
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• 1997

본 논문에서는 사개맞춤으로 제작된 우리 나라 전통 초가삼간 목조 프레임의 수평방향 교번하중에 대한 이력특성을 실험을 통하여 규명하였다. 실험에는 1.:1 모델을 제작하여 사용하였다. 사개맞춤 목조 프레임의 이력특성은 못이나 사재를 사용한 목조 프레임의 이력특성과는 매우 상이하다. 프레임의 등가 점성감쇠비는 평주 프레임의 경우 약 27%, 고주 프레임의 경우 약 13%이다. 개량형 Double Target 모델의 이용하여 비선형 이력특성을 모사하였다.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.852-860
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• 2003

We introduce the error models for an attitude determination system(ADS) with gyroscopes and stellar sensor. The ADS error models are derived according to the definition of the reference frame and of the attitude error. The equivalent error models applicable to the attitude determination system with large attitude errors are presented. The simulation results show that the proposed error models improve performance of the attitude determination system.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.423-437
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• 2009

In order to perform a step-by-step force-displacement response analysis or dynamic time-history analysis of large buildings with masonry infilled R/C frames, a continuous force-deformation model based on an equivalent strut approach is proposed for masonry infill panels containing openings. The model, which is applicable for degrading elements, can be implemented to replicate a wide range of monotonic force-displacement behaviour, resulting from different design and geometry, by varying the control parameters of the model. The control parameters of the proposed continuous model are determined using experimental data. The experimental program includes fifteen 1/3-scale, single-story, single-bay reinforced concrete frame specimens subjected to lateral cyclic loading. The parameters investigated include the shape, the size, the location of the opening and the infill compressive strength. The actual properties of the infill and henceforth the characteristics needed for the diagonal strut model are based on the assessment of its lateral resistance by the subtraction of the response of the bare frame from the response of the infilled frame.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.421-429
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• 2019

This paper presents an analytical model for the estimation of initial lateral stiffness of steel moment resisting frames with masonry infills. However, rather than focusing on the single bay-single storey substructure, the developed model attempts to estimate the global stiffness of multi-storey and multi-bay frames, using an assembly of equivalent springs and taking into account the shape of the lateral loading pattern. The contribution from each infilled frame panel is included as an individual spring, whose properties are determined on the basis of established diagonal strut macro-modeling approaches from the literature. The proposed model is evaluated parametrically against numerical results from frame analyses, with varying number of frame stories, infill openings, masonry thickness and modulus of elasticity. The performance of the model is evaluated and found quite satisfactory.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.383-394
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• 2021

Column foot in traditional Chinese timber structures may be subjected to be uplifted due to the lateral load and subsequently reset under the vertical loads. The residual moment of the rocking column foot is the most important parameter representing the mechanical behaviors of column foot, and the simplification of joints is the basis of structural analysis of whole structure. The complicated mechanical behaviors of joint and the modeling of the column foot joint has been undertaken historically based on the experiments and numerical simulation. On the condition of limited application range of those models, a lack of simplified model to represent the mechanical behaviors of joint deserves attentions. There is a great need to undertake theoretical studies to derive the residual moment and make better simplified model of the joint. This paper proposes the residual moment and equivalent simplified model of the rotational stiffness for column foot joint. And, the timber frame is established based on the simplified model, which is verified by solid finite element model. Results show that a mutual agreement on the mechanical behaviors of the timber frame is obtained between the simplified model and the solid finite element model. This study can serve as the references of the structural analysis for the traditional timber structures.

• 한국전산구조공학회논문집
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• 제16권2호
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• pp.173-182
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• 2003

비선형 정적해석 및 에너지를 이용한 설계방법에서는 구조물을 등가의 단자유도계로 치환하여 해석하는 것이 일반적이다. 본 연구에서는 지진하중에 의한 3층, 8층, 20층 철골 모멘트저항골조(MRF), 비좌굴 가새골조(BRBF)와 힌지접합 비좌굴 가새골조 (DTBF) 구조물의 에너지 요구량을 등가 단자유도계 시스템(ESDOF)의 에너지 요구량과 비교하여 등가단자유도계로 치환하는 방법의 타당성을 검토하였다 입력에너지와 이력에너지를 산정하기 위하여 연암 지반, 연약한 토사, 단층 근처의 지반에서 계측된 60개의 지진을 사용하였으며, 모드 질량계수가 0.8보다 작은 경우 ESDOF로 변환할 때 고차모드의 효과를 고려하였다. 연구결과에 따르면 3층과 8층 MRF와 DTBF에서의 이력에너지와 입력에너지는 ESDOF의 해석결과와 비교적 잘 일치하였다. 그러나 20층 BRBF에서는 ESDOF의 결과가 본 구조물의 결과를 과소평가하는 것으로 나타났다.

• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.89-118
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• 2015

The geometric nonlinearity of off-diagonal bracing system (ODBS) could be a complementary system to covering and extending the nonlinearity of reinforced concrete material. Finite element modeling is performed for flexural frame, x-braced frame and the ODBS braced frame system at the initial phase. Then the different models are investigated along various analyses. According to the experimental results of flexural and x-braced frame, the verification is done. Analytical assessments are performed in according to three dimensional finite element modeling. Nonlinear static analysis is considered to obtain performance level and seismic behaviour, and then the response modification factors calculated from each model's pushover curve. In the next phase, the evaluation of cracks observed in the finite element models, especially for RC members of all three systems is performed. The finite element assessment is performed on engendered cracks in ODBS braced frame for various time steps. The nonlinear dynamic time history analysis accomplished in different stories models for three records of Elcentro, Naghan and Tabas earthquake accelerograms. Dynamic analysis is performed after scaling accelerogram on each type of flexural frame, x-braced frame and ODBS braced frame one by one. The base-point on RC frame is considered to investigate proportional displacement under each record. Hysteresis curves are assessed along continuing this study. The equivalent viscous damping for ODBS system is estimated in according to references. Results in each section show the ODBS system has an acceptable seismic behaviour and their conclusions have been converged when the ODBS system is utilized in reinforced concrete frame.

• Steel and Composite Structures
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• 제1권2호
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• pp.213-230
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• 2001

This paper presents a simplified approach for the design of semi-continuous composite beams in braced frames, where specific attention is given to the effect of joint rotational stiffness. A simple composite beam model is proposed incorporating the effects of semi-rigid end connections and the nonprismatic properties of a 'cracked' steel-concrete beam. This beam model is extended to a sub-frame in which the restraining effects from the adjoining members are considered. Parametric studies are performed on several sub-frame models and the results are used to show that it is possible to correlate the amount of moment redistribution of semi-continuous beam within the sub-frame using an equivalent stiffness of the connection. Deflection equations are derived for semi-continuous composite beams subjected to various loading and parametric studies on beam vibrations are conducted. The proposed method may be applied using a simple computer or spreadsheet program.

• 한국기계가공학회지
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• 제13권1호
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• pp.8-15
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• 2014

This study investigates structural and vibration analyses for three types of bike frame fork models. As long as the maximum equivalent stresses of these models are lower than the yield stress, the three models are considered to be safe structurally. Type 3, with a maximum equivalent stress of 169.23 MPa, has the lowest stress among the three models and the strongest strength. Types 1, 2 and 3 have natural frequencies lower than 270 Hz. Type 3, with a critical frequency of 118 Hz, has the best durability under vibration among the three models. In order to decrease the vibration transmitted to a bike rider riding on a rough road, the impact due to vibration can be relieved by selecting a Type 3 model from among the three models. The results of this study can be effectively utilized for the design of a bike frame fork as this allows the anticipation and prevention of damage caused by durability issues.

• 한국지진공학회논문집
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• 제18권1호
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• pp.53-61
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• 2014

RC shear wall sections which have irregular shapes such as T, ㄱ, ㄷ sections are typically used in low-rise buildings in Korea. Pushover analysis of building containing such members costs a lot of computation time and needs professional knowledge since it requires complicated modeling and, sometimes, fails to converge. In this study, a method using an equivalent column element for the shear wall is proposed. The equivalent column element consists of an elastic column, an inelastic rotational spring, and rigid beams. The inelastic properties of the rotational spring represent the nonlinear behavior of the shearwall and are obtained from the section analysis results and moment distribution for the member. The use of an axial force to compensate the difference in the axial deformation between the equivalent column element and the actual shear wall is also proposed. The proposed method is applied for the pushover analysis of a 5- story shear wall-frame building and the results are compared with ones using the fiber elements. The comparison shows that the inelastic behavior at the same drift was comparable. However, the performance points estimated using the pushover curves showed some deviations, which seem to be caused by the differences of estimated yield point and damping ratios.