• 한국공간구조학회논문집
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• 제10권2호
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• pp.61-68
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• 2010

최근에 폭설로 인한 온실의 붕괴가 빈번해져서 농가의 피해가 증가되고 있다. 히지만 폭설로 인한 온실의 붕괴를 막기 위한 정확한 구조해석에 대한 연구가 미약하여 매년 농가의 피해는 되풀이 되고 있다. 기존 온실의 구조해석 방법은 미소변위에 기초한 선형탄성해석으로 이루어지고 있다. 그러나 실제 온실의 강성은 건축 구조물의 강성에 비해 상당히 약하지만 하중은 폭설에 의해 상대적으로 크게 작용하여 변형이 크게 발생하고 구조물의 기하학적 형태가 변하므로 변형률-변위 관계가 비선형 거동을 한다. 본 연구에서는 폭설에 따른 온실의 붕괴를 막기 위하여 농가에서 많이 사용되는 농가 지도형 G형 단동온실과 농가보급형인 1-2W 기본형 연동온실에 대해 시간에 따른 하중단계별 기하학적 비선형 효과를 고려하여 온실의 정확한 거동분석과 구조적 안전성을 평가하는데 대변위해석 방법을 제시하고자한다.

• 대한토목학회논문집
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• 제5권3호
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• pp.107-115
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• 1985

초기(初期)처짐을 가지는 평판(平板)이 일보면내압축하중(一輔面內壓縮荷重)을 받을 때의 거동을 살피기 위하여 새로운 변위함수(變位凾數)를 도입(導入)한 유한대판법(有限帶板法)을 정식화(正式化)하고, 이 이론(理論)에 따라 컴퓨터 프로그램을 편성(編成)하여 여러 경우에 대한 평판(平板)의 거동을 계산(計算)하고 이미 발표된 결과(結果)와 비교해 보았는데 그 요점은 다음과 같다. 1. Curvature effect를 고려하여 면외변위(面外變位)함수로부터 유도한 식을 참고로 하여 새로운 면내변위(面內變位) 함수를 가정하고 이것을 대판요소(帶板要素)의 변위(變位)함수로 사용한 유한대판법(有限帶板法)을 안식화(定式化)하였다. 2. 위에서 안식화(定式化)한 유한대판법(有限帶板法)에 따라 편성(編成)한 프로그램을 써서 수치해석한 결과 변위증분방식(變位增分方式)이 하중증분방식(荷重增分方式)보다 수렴이 빨랐다. 3. 일축압축(一軸壓縮)을 받는 평판(平板)을 여려 경우에 대해 위의방법으로 해석한 결과는 해석적(解析的) 방법(方法)이나 Crisfield(D)에 의(依)한 유한요소법(有限要素法)으로 얻어진 결과와 잘일치 하였다. 따라서 위의 방법은 평판의 비선형해석을 위한 하나의 유용한 방법으로 생각된다.

• Steel and Composite Structures
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• 제43권2호
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• pp.139-152
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• 2022

Steel-reinforced concrete (SRC) L-shaped column is the vertical load-bearing member with high spatial adaptability. The seismic behavior of SRC L-shaped column is complex because of their irregular cross sections. In this study, the hysteretic performance of six steel truss reinforced concrete L-shaped columns specimens under the combined loading of compression, bending, shear, and torsion was tested. There were two parameters, i.e., the moment ratio of torsion to bending (γ) and the aspect ratio (column length-to-depth ratio (φ)). The failure process, torsion-displacement hysteresis curves, and bending-displacement hysteresis curves of specimens were obtained, and the failure patterns, hysteresis curves, rigidity degradation, ductility, and energy dissipation were analyzed. The experimental research indicates that the failure mode of the specimen changes from bending failure to bending-shear failure and finally bending-torsion failure with the increase of γ. The torsion-displacement hysteresis curves were pinched in the middle, formed a slip platform, and the phenomenon of "load drop" occurred after the peak load. The bending-displacement hysteresis curves were plump, which shows that the bending capacity of the specimen is better than torsion capacity. The results show that the steel truss reinforced concrete L-shaped columns have good collapse resistance, and the ultimate interstory drift ratio more than that of the Chinese Code of Seismic Design of Building (GB50011-2014), which is sufficient. The average value of displacement ductility coefficient is larger than rotation angle ductility coefficient, indicating that the specimen has a better bending deformation resistance. The specimen that has a more regular section with a small φ has better potential to bear bending moment and torsion evenly and consume more energy under a combined action.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1949-1957
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• 2000

All the loads in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. The dyna mic factors are generally determined based on experiences. Therefore, the static loads can cause problems in precise analysis and design. An analytical method based on modal analysis has been proposed for the transformation of dynamic loads into equivalent static load sets. Equivalent static load sets are calculated to generate an identical displacement field in a structure with that from dynamic loads at a certain time. The process is derived and evaluated mathematically. The method is verified through numerical tests. Various characteristics are identified to match the dynamic and the static behaviors. For example, the opposite direction of a dynamic load should be considered due to the vibration response. A dynamic bad is transformed to multiple equivalent static loads according to the number of the critical times. The places of the equivalent static load can be different from those of the dynamic load. An optimization method is defined to use the equivalent static loads. The developed optimization process has the same effect as the dynamic optimization which uses the dynamic loads directly. Standard examples are solved and the results are discussed

• 대한기계학회논문집A
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• 제20권12호
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• pp.3767-3781
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• 1996

Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.

• Earthquakes and Structures
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• 제13권4호
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• pp.409-419
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• 2017

In order to analyze the vibration control effect of viscous damper in the concrete archaized buildings with lintel-column joints under seismic action, 3 specimens were tested under dynamic excitation. Two specimens with viscous damper were defined as the controlled component and one specimen without viscous damper was specified as the non-controlled component. The loading process and failure patterns were obtained from the test results. The failure characteristics, skeleton curves and mechanical behavior such as the load-displacement hysteretic loops, load carrying capacity, degradation of strength and rigidity, ductility and energy dissipation of the joints were analyzed. The results indicate that the load-bearing capacity of the controlled component is significantly higher than that of the non-controlled component. The former component has an average increase of 27.4% in yield load and 22.4% in ultimate load, respectively. Meanwhile, the performance of displacement ductility and the ability of energy dissipation for the controlled component are superior to those of the non-controlled component as well. Compared with non-controlled component, equivalent viscous damping coefficients are improved by 27.3%-30.8%, the average increase is 29.0% at ultimate load for controlled component. All these results reflect that the seismic performance of the controlled component is significantly better than that of the non-controlled component. These researches are helpful for practical application of viscous damper in the concrete archaizing buildings with lintel-column joints.

• Computers and Concrete
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• 제20권2호
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• pp.229-246
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• 2017

The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

• 한국정밀공학회지
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• 제25권2호
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• pp.49-56
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• 2008

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.

• Architectural research
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• 제15권1호
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• pp.43-52
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• 2013

The reinforced concrete shear walls are being widely used in the domestic high-rise residential complex buildings. If designed by current codes, the special boundary element is needed in almost all high-rise shear wall buildings. This is because the equation for determining the provision of the special boundary element in the current codes cannot reflect the characteristics of the domestic high-rise shear walls with high axial load ratio and high proportion of elastic displacement to total displacement. In this study, a new equation to be able to reflect the characteristics is proposed. By using the equation, the special boundary element may not be necessary in certain cases so that structural engineers can relieve the burden of installing the special boundary element in every high-rise shear wall.

• 대한기계학회논문집A
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• 제29권4호
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• pp.555-562
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• 2005

In this study, we tried to establish the method of evaluating the tensile properties of the ring specimen of Arsene which have gauge length. In this result, we verified the availability of central piece. We made ring specimens and devices such as central piece, pins, and clevises. A proper tensile speed was determined by pre-test. The result of main test was calibrated and compared with the result of FEM. To obtain the tensile properties from the ring test result, we observed two relationships: one is strain-displacement and the other is load ratio-displacement. The tensile properties could be evaluated by using these relationships.