Restraints of Branch Lines are used as earthquake-resistant support devices for fire-fighting pipes along with sway brace devices. The central types are aligned and fixed in a straight line with center of the pipe, but the eccentric types are fixed to on side of the pipe, so a bending moment occurs. In this study, three specimens each of central type and eccentric type were installed at an angle of 45° from the vertical and a monotonic compression load of 1340N was applied. All central type samples satisfied 17.8mm of the allowable displacement, but all eccentric type samples failed to meet the target load and buckled. Therefore, when considering the performance of eccentric type restraints, both compressive load and bending moment must be considered. Even through material mechanics calculations, the yield stress of eccentric type - 3/8 inch all threaded steel bolt - exceeds 320Mpa of the allowable stress. A experiment standards need to be established for eccentric type restraints.

For important structures such as nuclear power plants, In-Structure Response Spectrum (ISRS) analysis is essential because it evaluates the safety of equipment and components installed in the structure. Because most structures are asymmetric, the response can be affected by eccentricity. In the case of seismically isolated structures, this effect can be greater due to the difference between the center of mass of the structure and the center of rigidity of the isolator layer. Therefore, eccentricity effects must be considered when designing or evaluating the ISRS of seismically isolated structures. This study investigated the change of the ISRS of an isolated structure by assuming accidental eccentricity. The variables that affect the ISRS of the isolated structure were analyzed to see what additional impact they had due to eccentricity. The ISRS of the seismically isolated structure with eccentricity was amplified more than when there was non-eccentricity, and it was boosted more significantly in specific period ranges depending on the isolator’s initial stiffness and seismic intensity. Finally, whether the displacement requirement of isolators can be applied to the variation of the ISRS due to eccentricity in the design code was also examined.

In the case of a school building, even though it is a regular structure in terms of plan shape, if the masonry infill wall acts as a lateral load resisting element, it can be determined as a torsionally irregular building. As a result, the strength and ductility of the structure are reduced, which may cause additional earthquake damage to the structure. Therefore, in this study, a structure similar to a school building with torsional irregularity was selected as an example structure and the damping performance of the PC-BRB was analyzed by adjusting the eccentricity according to the amount of masonry infilled wall. As a result of nonlinear dynamic analysis after seismic reinforcement, the torsional irregularity of each floor was reduced compared to before reinforcement, and the beams and column members of the collapse level satisfied the performance level due to the reduction of shear force and the reinforcement of stiffness. The energy dissipation of PC-BRB was similar in the REC-10 ~ REC-20 analytical models with an eccentricity of 20% or less. REC-25 with an eccentricity of 25% was the largest, and it is judged that it is effective to combine and apply PC-BRB when it has an eccentricity of 25% or more to control the torsional behavior.

The energy dissipation of inverted V-type eccentric steel braced frames can be achieved through the yielding of a slit link, through yielding of a number of strips between slits when the frame is subjected to inelastic cyclic deformation. On the other hand, the development of seismic resistance system without residual deformation is obtained by applying the superelasdtic shape memory alloy (SMA) material into the brace and link elements. This paper presents results from a systematic three-dimensional nonlinear finite element analysis on the structural behavior of the eccentric bracing systems subjected to cyclic loadings. A wide scope of structural behaviors explains the horizontal stiffness, hysteretic behaviors, and failure modes of the recentering eccentric bracing system. The accurate results presented here serve as benchmark data for comparison with results obtained using modern experimental testing and alternative theoretical approaches.

본 논문에서는 유한요소해석 프로그램 Abaqus를 이용하여 고온과 편심 축하중을 받는 세장한 철근 콘크리트 기둥의 유한요소해석 절차를 제시하고 해석 결과를 비교･분석하였다. 기둥에 축하중과 화재가 가해지는 상황을 해석에 반영하기 위해 Abaqus에서 제공하 는 순차 결합 열-응력 해석을 사용하였다. 우선 콘크리트 단면에 대한 열전달 해석을 수행하여 검증한 뒤, 이를 3차원 요소로 확장하고 구조해석과 결합하여 해석을 수행하였다. 해석 과정에서 수렴성 및 정확성에 영향을 미치는 인장 증강 효과와 초기 불완전성을 고려 하여 모델링하였다. 해석 결과는 74개 실험 데이터와 비교하였으며, 내화시간을 기준으로 평균 6%의 오차를 나타냄에 따라 유한요소 해석을 통해 철근콘크리트 기둥의 내화성능을 예측할 수 있게 되었다.

프로펠러축은 프로펠러 하중 및 편심추력의 영향으로 인해 정적, 동적, 과도상태 각각 거동의 패턴이 달라져 선미관 후부베어 링의 국부하중 변화를 일으킴으로써 선박 축계의 안정성에 큰 영향을 미치며, 결과적으로 축 지지 베어링의 손상위험을 증가시킨다. 이를 방지하기 위한 일련의 축계정렬연구는 선급강선규칙과 조선소 지침을 기반으로 준정적 상태에서 축과 선미관 베어링간의 상대적 경사각 과 유막유지, 선체변형에 따른 영향평가를 최적화 하는데 중점을 두어 진행 되어왔다. 그러나 보다 진일보한 형태의 추진축계의 안정성을 보장하기 위해서는 조타장치의 전타시 발생하는 급격한 선미유동장 변화와 같은 과도동적상태변화 조건에서의 상세 연구가 필요하다. 이 러한 관점 하에 본 연구에서는 50,000 DWT 중형 유조선을 대상으로 스트레인 게이지법과 변위센서을 이용하여 선박운전 중 대표적 과도 상태인 좌현 전타시의 프로펠러 축 거동이 선미관 베어링에 미치는 영향을 교차검증한 결과, 프로펠러 편심추력변동이 선미관 베어링의 하중을 일시적으로 저감시켜 베어링 하중을 완화시키는 것을 확인하였다.

편심가새골조(EBF)의 역량설계법에 의하면, 링크가 완전항복 및 변형경화 상태일 때 기둥, 링크외부보, 가새(비소산 부재)는 탄성 거동해야 한다. 현행 AISC 341은 역량설계에 필요한 변형도경화계수(SHF)를 1.25로 제시하고 있으나, 실제로 건물이 고층 규모일수 록 모든 링크가 이처럼 동등한 수준의 초과강도에 도달할 가능성은 매우 낮아진다. 본 연구에서는 링크의 SHF를 정밀하게 예측하는 방법을 제안함으로써, 역량설계법의 목적을 달성하면서 구조물량을 절감하고자 하였다. 제안한 방법의 효과를 검증하기 위해 선형해 석을 2회 수행하여 SHF를 예측하고, 이를 비선형 해석결과와 비교하였다. 다음으로 비선형 해석에 의한 응답을 분석하여 구조물의 한 계상태에서 비소산 부재들의 항복 여부를 확인하였다. 그 결과, 본 연구의 방법으로 설계된 구조물은 링크의 SHF를 정확히 예측함으 로 인해 물량이 큰 폭으로 절감되었으며, 비소산 부재들도 모두 탄성상태를 만족하는 것으로 나타났다.

본 연구에서는 철골편심가새골조 시스템을 대상으로 다목적최적화기법을 통해 설계를 수행하고 그 결과를 분석하였다. 최적화 설 계를 위해 유전 알고리즘의 일종인 NSGA-II를 활용하였다. 여기서, 목적함수는 이율배반적 관계를 갖는 구조물량과 층간변위로 하여 최소화되고, 제약조건에는 구조기준에서 요구하는 내력비, 링크의 회전각 등을 포함하였다. 제약조건은 최적화 알고리즘 내에서 각 항목을 위반할수록 목적함수 값을 크게 증가시키는 벌금함수의 형태를 가지고 있다. 설계기준에서 EBF 시스템의 설계규정은 링크 부재만 항복이 허용되며 나머지 부재는 링크 항복 시 발생되는 부재력을 탄성상태에서 견디도록 의도한 역량설계법에 기초한다. 그러나 최적화를 통해 도출된 결과 중 일부는 구조기준의 설계조항은 만족하지만 특정층 링크에 소성변형이 집중되어 연약층을 형성함 으로써 기준에서 의도하는 역량설계의 원칙을 위배하는 결과가 나타났다. 이를 해결하기 위해 모든 링크의 전단 초과강도계수 중 최 대값이 최소값의 1.25배를 넘지 않도록 하는 제약식을 추가하였다. 새로운 제약식을 추가한 경우 모든 최적해는 설계기준과 역량설계의 원칙을 준수하는 것으로 나타났다. 모든 설계안에서 보 경간에 대한 링크의 길이비는 전단링크의 범주에 해당하는 10% ~ 14%였다. 전체적으로 설계안들은 링크의 초과강도 계수비가 가장 지배적인 제약으로 작용하였으며, 구조기준의 요구사항 중 층간변위와 내력비 등의 항목에서 허용치에 비해 매우 보수적으로 설계되었다.

Background: Limitations in hip flexion caused by tight hamstrings lead to excessive lumbar flexion and low back pain. Accordingly, many studies have examined how to stretch the hamstring muscle. However, no study has focused on the effect of hamstring eccentric exercise for tight hamstrings on trunk forward bending. Objects: We compared the short-term effect of hamstring eccentric exercise (HEE) and hamstring static stretching (HSS) on trunk forward bending in individuals with tight hamstrings. Methods: Thirty individuals with tight hamstrings participated in the study. The subjects were randomly allocated to either a HEE or HSS group. To determine whether the hamstrings were tight, the active knee extension (AKE) test was performed, and the degree of hip flexion was measured. To assess trunk forward bending, subjects performed the fingertip to floor (FTF) and modified modified Schober tests, and the degree of trunk forward bending was measured using an inclinometer. We used paired t-tests to compare the values before and after exercise in each group and independent t-tests to compare the two groups on various measures Results: The FTF test results were improved significantly after the exercise in both groups, and AKE for both legs increased significantly in both groups. There was no significant difference in the hip angles, mmS test results, or degree of trunk forward bending between groups after the exercise. No test results differed significantly between the two groups at baseline or after the exercise. Both groups increased hamstring flexibility and trunk forward bending. Conclusion: HSS and the HEE groups increased hamstring flexibility and trunk forward bending. However, HEE has additional benefits, such as injury prevention and muscle strengthening.

본 연구에서는 구조단열패널을 구조 벽체로서 활용하기 위하여 개구부를 설치한 후 편심축하중 실험 및 해석을 수행 하였다. 실험체의 크기는 1200×2400㎜이다. 실험체는 7개로서 개구부의 크기와 개구부 보강방법, 강재를 시용한 구조단열패널 보강을 변수로 하여 진행하였다. 구조단열패널에 대하여 개구부 설치에 따른 구조적 거동을 분석하기 위한 변수해석을 수행하였다. 구조성능 실험 결과와의 비교분석을 통해 해석에 대한 검증을 하였고, 개구부 크기를 변수로 하여 편심축하중을 받는 구조단열패널의 구조적 거동을 유한요소해석을 통하여 분석하였다. 이를 통해 구조단열패널에 적합한 최적의 개구부 형상을 제안 하고자 한다.

선박 축계는 프로펠러 하중의 영향으로 선미관 후부베어링의 국부하중 증가가 현저히 나타나 축계 선미관 베어링 손상의 위험이 증대된다. 이를 방지하기 위해 수행된 추진축계 정렬연구는 주로 준정적 상태(quasi-static condition)에서 축과 지지베어링간의 상대적 경 사각을 감소시키는데 중점을 두어 진행되어 왔다. 그러나 보다 상세한 평가를 위해서는 동적상태를 추가로 고려하는 것이 필요하다. 4,70 0 DWT 선박을 대상으로 NCR로 운전중 급속으로 우현 전타할 때 추진축계가 받는 영향에 대해 연구하였다. 연구결과 선미 유동장 변화 에 의해 프로펠러 편심추력이 과도 상태가 되어 프로펠러에 불평형 진동이 유발되는 것을 확인하였다. 우현 전타시의 프로펠러 편심추력은 NCR 조건대비 축을 선미관 베어링으로부터 들어 올리는 힘으로 작용하여 선미관 베어링 하중완화에 기여하고 있음을 확인하였다.

Eccentric axial load tests were carried out to investigate the structural performance of the SIP (Structural Insulation Panel), which is widely used as residential type in Europe and North America. Outside the country, design standards for SIP have been prepared and related research has been carried out variously. However, in Korea, the research on the performance of the structural insulation panel is very small, and the related standard is not provided. In this study, the eccentric axial load was applied after the opening was installed to utilize the structural insulation panel as the structural wall. The size of the test specimen was 1200 × 2400㎜. The number of test specimens was 6, and the size of the openings and the reinforcement method around the openings were used as variables.

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

As the ridges become larger and larger, a structural type that enables effective utilization of the long span and space is required. In the construction stage, the steel column supports the installation load. However, in order to secure the stability against the out - of - plane deformation of the steel column due to the lateral pressure when the concrete is laid, a binding frame is installed inside the steel pipe at constant intervals to resist the concrete installation pressure. When the concrete is cured and its performance as a composite section is exerted, a stress is generated which pushes the steel pipe out of the plane by the column compressive force. In this case, since the binding frame controls the deformation, the local buckling is delayed and the constraining effect on the concrete is increased. In order to evaluate the structural performance and behavior of the composite mega column according to the eccentricity effect and the effect of the binding frame, we carried out a structural test by fabricating eight monopole specimens with the binding frame reinforcement, reinforcing gap, reinforced cross section and eccentricity , And the experimental results are compared with the KBC2016 design formula.

So far, square concrete filled tubular(CFT) columns have been used in a limited width thickness ratio. The reason is that local buckling occurs in steel tube easily. Once the local buckling occurs, the confinement effect of steel tube on concrete disappears. In this study, we developed welded built-up square steel tube with reinforcement which are placed at the center of the tube width acts as an anchor. 3 specimens of slender welded built-up square CFT columns and 3 specimens of slender welded built-up square steel tube columns were manufactured with parameters of width(B) of steel tube, width thickness ratio(B/t). we conducted a experimental test on the 6 specimens under eccentric load, and evaluated the structural resistance and behavior of 6 specimens.

CFST columns are structurally superior because the concrete inside the steel tubes prevents local buckling at the tubes and the tubes confine the concrete. And, the thickness of steel tube in CFST column has been thinner with development of high-strengh steel. The thinner the steel tube of a square CFST column is, the more local buckling is likely to occur. For this reason, we developed welded built-up square steel tube with stiffeners which are placed at the center of the tube width acts as an anchor. In this study, we conduct experimental test for three specimens of the 4m long span welded built-up square CFT column with parameters of L/D and D/t. And, the test results were compared with the analysis results by M-ϕ-P Program.

The objective of this study is to calculate flow characteristics and structural safety for triple offset eccentric butterfly valve. The triple offset butterfly valve used in this study was 600mm in size, and the opening angles were 30 degree, 60degree and 90 degree. Structural and flow analysis of triple offset eccentric butterfly valve are carried out by using commercial code ANSYS and CFX version 14. The flow coefficient, Kv, increases as the valve opening increases. The results from fluid structure coupled analysis, maximum equivalent stress was calculated 462.06MPa at opening angle 60 degree

In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification factor (TAF), and the inherent and accidental eccentricities. When a structure of less than 6-stories and assigned to seismic design category C or D is designed using equivalent static analysis method, both KBC-2006 and KBC-2009 use the TAF but apply different calculation methods for the of design eccentricity. The design eccentricity in KBC-2006 is calculated by multiplying the sum of inherent eccentricity and accidental eccentricity at each level by a TAF but that in KBC-2009 is calculated by multiplying only the accidental eccentricity by a TAF. In this paper, the damage indices of a building with planar structural irregularity designed by different design eccentricities are compared and the relationship between the earthquake damage and design eccentricity of the building is evaluated. On the basis of this study, the increment of design eccentricity results in the decrement of final eccentricity and global damage index of structure. It is observed that design eccentricity in KBC-2006 reduces the vulnerability of torsional irregular building compared to design eccentricity in KBC-2009.

For most of recent tall buildings, one characteristic is that their building shapes vary with height such as taper and setback, and this implies that the distribution of their structural components may also vary with height. Because of these structural variations, although the sectional shapes of these buildings are symmetric, it is difficult to say whether or not they are structurally symmetric. The acceleration responses of structurally asymmetric tall buildings are larger than those of non-eccentric buildings, thus raising the possibility of problems during strong winds and typhoons. This paper describes wind tunnel tests carried out using building models with height variations and acceleration response analyses, and discusses the resulting response characteristics. For tapered and setback buildings, although the across-wind accelerations are larger than those of a square building, the total root-mean-square accelerations remain small because of smaller along-wind and torsional rms accelerations. And it was found that the effects of statistical couplings between along-wind force and other two forces are negligible.