When the center of stiffness and the center of mass of the structure differ under the seismic load, torsion is caused by eccentricity. In this study, an analysis model was modeled in which the positions of the core and the plane rotation axis of a 60-story torsional atypical structure with a plane rotation angle of 1 degree per floor were different. The structural behavior of the analysis model was analyzed, and the earthquake response behavior of the structure was analyzed based on the time history analysis results. As a result, as the eccentricity of the structure increased, the eccentricity response was amplified in the high-rise part, and the bending and torsional behavior responses were complex in the low-order vibration mode. As a result of the analysis, the maximum displacement and story drift ratio increased due to the torsional behavior. The maximum story shear force and the story absolute maximum acceleration showed similarities for each analysis model according to the shape of the vibration mode of the analysis model.

In this paper, the dynamic response was analyzed by performing linear dynamic analysis using historic earthquake loads on twisted-shaped structures and fixed structure among free-form high-rise structures with atypical elevation shape following prior studies. In addition, the dynamic characteristics of the analysis models according to the plane rotation angle of the twisted structure were compared and analyzed. As a result of the analysis, as the plane rotation angle of the twisted structure increased, the interlayer deformation rate increased in the high-rise part of 50th floors or more. The story shear force and the story absolute acceleration were similar in the entire structure. In the case of the story shear force, the response of the twisted shape model was rather reduced in the middle part. As a result of analyzing the dynamic response, the vulnerable layer where the response amplification of the twisted structure occurs was found to be 31st story.

In order to commercialize large diameter PP pipes, the cutting work was attempted with the cutting machine (∅18″and AL120 cutter, 2100 r.p.m) used for the conventional PE or PVC pipe(∅1200 mm, t 70), but the cutting work was failed because the material of “PP pipe” melted and sticked to the surface of the wheel-cutter. In order to find the optimal structure and number of blades for wheel-cutters, an experimental investigation the temperature measurement of specimen and wheel-cutter and the visualization of cutted specimen surface and chip shape were carried out during and after experiment. In addition, modelings for cutting and heat transfer mechanisms have been developed for theoretical analysis. The theoretical and experimental results were in good agreement. The results show that the appropriate structure and the rotational speed of wheel-cutter are W60 and 650 rpm for the large diameter PP pipe cutting machine.

In order to develop the compatible damping device in various vibration source, a hybrid wall-type damper combining slit and friction damper in parallel was developed. Cyclic loading tests and two-story RC reinforced frame tests were performed for structural performance verification. As a result of the 5-cyclic loading test according to KBC-2016 and low displacement cyclic fatigue test, The hybrid wall type damper increased its strength and the ductility was the same as that of the slit damper. In addition, As a result of the two-layer frame test, the reinforced frame had about twice the strength of the unreinforced frame, and the story drift ratio was satisfied to Life Safety Level.

본 논문에서는 합성단면을 갖는 구조물의 극한 거동 해석에서 요구하는 재료 및 기하학적 비선형 해석을 수행하기 위한 보 요소를 제시하였다. 제안된 요소는 기하학적 비선형성을 효과적으로 모사할 수 있는 co-rotational 정식화를 통해 도출되 었으며, 다양한 합성단면의 저항성능을 재현할 수 있도록 화이버 단면법이 요소의 내력 및 강성을 산정하는데 활용되었다. 제안된 방법을 구현할 수 있도록 해석 프로그램이 개발되었으며, 호장법을 적용하여 최대내력 발생 이후의 연성거동뿐만 아 니라 심한 비선형 응답(snap-through 또는 snapback)까지 추적해낼 수 있도록 하였다. 본 연구에서 제안된 요소 정식화와 해석 프로그램의 정확성을 검증을 위해 몇 가지 수치예제가 수행되었고, 해석결과는 제안된 요소의 정확성과 효율성을 보이 기 위해 3차원 연속체 모델 및 기존 연구의 결과와 비교되었다. 추가로 합성단면을 갖는 골조 구조물에 대한 수치예제를 통 해, 합성단면을 구성하는 재료의 탄성계수 비 및 강도 비에 따른 영향을 분석하였다. 해석결과는 외층 재료의 탄성계수가 증 가됨에 따라 준취성 거동이 나타났으며, 외층 재료의 항복강도가 높을수록 선형 거동하는 기하적 비선형 응답과 유사한 응 답을 보였다.

Displacement response of structure is valuable information for monitoring an structure integrity. However, measuring the displacement response is difficult than other structure responses, such as acceleration, strain, and angle. So, previous researches have focused on displacement estimation technique using measured acceleration. The displacement estimation methods also have weakness that filtering noise of measured data is so complicate. The estimated displacement might be diverged because of the measuring noise. Because of these reasons, this study focused on rotation angle. This study developed a algorithm for estimating displacement and structure deformed shape using rotation angle.

The new rotary friction damper was developed using several two-nodal rotary frictional components with different clamping forces. Because of these components, the rotary friction damper can be activated by building movements due to lateral forces such as a wind and earthquake. In this paper, various dependency tests such as displacement amplitude, forcing frequency and long term cyclic loading were carried out to evaluate on the structural performance and the multi-slip mechanism of the new damper. Test results show that the multi-slip mechanism is verified and friction coefficients are dependent on displacement amplitute and forcing frequency except long term cyclic loading.

Various hybrid dampers have been developed in Korea to control the vibration due to a wind and earthquake. In order to minimize the installment space, cost and construction process, the new hybrid friction damper is developed. This hybrid damper is composed of several rotary friction components having two frictional joint. Because of these components, the building vibration due to wind and earthquake can be mitigated by hybrid friction damper. In this paper, various dependency tests were carried out to evaluate on the structural performance of two joint rotational friction component of the hybrid damper. Test results show that two joint rotational components do not depend on a displacement and a frequency of forcing but friction coefficients is reducing as a clamping force is increasing.

회전하는 수조에서 나타나는 순압성 소용돌이의 패턴과 구조 회전에 대한 연구를 수행하였다. 소용돌이는 수면 위에 접촉된 원판을 수조에 대해 상대적으로 회전시키는 방법을 통해 만들어졌다. 회전원판의 크기, 회전방향, 회전속력에 따라 트라이폴라 소용돌이, 삼각형 소용돌이, 사각형 소용돌이, 커다란 원형 소용돌이가 안정하게 나타났고, 모양이 계속 변하는 불안정한 소용돌이도 나타났다. 회전원판과 수조 벽 사이의 간격이 안정한 소용돌이의 패턴에 큰 영향을 주었고 불안정한 소용돌이는 원판이 시계방향으로 빠르게 회전할 때 주로 나타났는데, 그 원인은 원심력적 불안정성이었다. 한편, 트라이폴라 소용돌이에서 나타난 전체 패턴의 구조적 회전 각속도는 원판 가장자리의 선속도에 비례하였고, 고기압성 트라이폴라 소용돌이가 저기압성 보다 더 큰 구조 회전 각속도를 가졌다. 로스비 수와 구조회전의 관점에서 볼 때, 해양에서 발견된 트라이폴라 소용돌이와 본 실험에서 나타난 트라이폴라 소용돌이는 유사하였다.

본 연구에서는 원형실린더 후류 와류에 의한 진동을 제어를 위해 적용되는 나선형 뱃전판의 효율향상을 위해 다양한 회전각에 대해 모델실험을 실시하였다.실험은 회류수조에서 레이놀즈수 Re=4.0×10³,Re=5.5×10³ 및 Re=7.0×10³에서 균일유입유동에서 2-프레임 그레이레벨 상호상관 PIV기법을 이용하였다.실험결과 원형실린더와 뱃전판을 부착한 실린더와의 비교를 통해..

The agitator with a reducer are usually using on the process of a water treatment. However, working the reducer at the field, a lubricant oil can leak out. It causes an environment pollution and a water service/sewerage pollution problem. In this study, the reducer with a drywell structure is developed in order to prevent the oil leakage. The drywell structure is that the reducer bottom housing and the support column of an output shaft are united, and taper roller bearings are in the bottom housing. During the development of the reducer, a mockup and a prototype are made by using CAD and a high speed CNC machine. Then, to prove the performance of the prototype, the performance tests, unload working test and the mechanical torque efficiency test, are conducted by the torque meter device. Also a motor velocity(rpm) control system is developed by a PID control according to the working loads(MLSS data). The results of the test are shown that the maximum torque efficiency is 88.45%, the oil leakage and the abnormal noise do not occur during the work. Therefore the reducer with the drywell structure and the motor rpm PID control system is successfully developed.

In this study, equivalent linear damping and stiffness of a single-degree-of-freedom(SDOF) structure with a rotational friction damper are estimated using the result of experiments and compared with those obtained from non-linear time history analyses. First, the transfer function of the test model is constructed and then the equivalent stiffness and damping are calculated, using the half-power bandwidth (HPB) method. For comparative study, those properties are estimated based on stochastic theory in the time domain. Both equivalent linear systems identified from experiments and numerical analyses correspond well. Further, it is observed that there exists an optimal clamping force on the rotational friction damper from estimated equivalent damping.

이 논문에서는 철근콘크리트 쉘구조의 동적해석을 위한 비선형 유한요소 해법을 제시하였다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위한 RCAHEST이다. 유한요소로서는 면내회전강성도를 갖는 4절점 평면 쉘요소가 사용되었다. 두께방향에 대한 철근과 콘크리트의 재료성질을 고려하기 위하여 층상화기법이 도입되었다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열모델을 사용하였다. 동적 평형방정식의 해는 HHT법에 의한 수치적분으로 구하였다. 신뢰성 있는 해석결과와 비교를 통하여 이 논문의 제안방법이 철근 콘트리트 쉘구조의 비선형 동적해석에 적합한 방법임을 입증하고자 한다.

This paper analyzed the effects of rotational stiffness of wedge connection between vertical and horizontal members of system supports. By simulating the connection condition both a hinge connection, which is considered in the design stage, and a spring with the rotational stiffness reflecting the actual behavior, the critical buckling load and the maximum combination stress ratio are compared. The results show that hinge condition somewhat underestimate the actual behavior of vertical members of system supports. However, it is also noted that the horizontal member represents the increased stress due to the rotational stiffness of the connection.

Recently, the rotational solar tracker system is presented for the high electric efficiency. The horizontal rotation tracker is the structure for rotationg horizontally the most important part. However, it is difficult to secure the safety and maintenance in solar tracker systems. Therefore, this study suggests the reasonable structure type for horizontal rotational solar tracker through the strength reinforcement of the structure to ensure stability.

In this study, a new damage detection method using an inclinometer which can directly measure rotational displacement is developed and its effectiveness investigated. In order to verify the attractive features of the proposed method such as an increase in sensitivity and the data loss minimization, numerical analyses were performed by the uniform load surface curvature (ULSC) method, which is the damage detection method based on the modal flexibility matrix. For numerical analysis, 2 m simply supported beam, which has 20 elements and 21 nodes is considered. From the results of the eigenvalue analysis, the damage locations were perfectly detected in each damage case. It shows that the damage detection using rotational displacement is theoretically possible. From the result of numerical simulations, the damage locations were detected exactly. When compared with the detection method based on vertical displacements obtained from accelerometers, it is shown that using the rotational displacement is much more sensitive than using the vertical displacement. Overall, when compared with the accelerometer data, the damage detection performed by an inclinometer was more sensitive.