태권도 몸통돌려차기 시 무릎관절에 작용하는 비틀림 모멘트(torsional moment)에 대한 분석

구본호,차명환 한국무예학회 2017 무예연구 Vol.11 No.2

The purpose of this study was to analyze knee joint torsional moment to predict the possibility of overuse injury on the ligaments and menisci which function to maintain the stability of the knee joint during Taekwondo roundhouse kicking. Sixteen Taekwondo sparring athletes who primarily use right leg for roundhouse kick were randomly selected and divided into two groups by sex(8 males and 8 females). All participants conducted roundhouse kick to hand mitt for preventing injuries and to perform kicking as real competition. The target height was ‘mom-tong’. Kinetic and kinemetic data collected by Vicon MX System which were composed of fourteen T160 IR cameras and two AMTI OR-6 force platforms and calculated knee joint reaction force by Kwon3D XP. All data were normalized at the time of event set for analysis, force normalized to body weight (BW) and leg length (BW·LL) by using Matlab 2016a. All collected data were smoothed by 4th order butterworth low-pass filter and the cut-off frequency was set at 10Hz. The data in this study was presented by descriptive statistics for each group by using SPSS 23.0. The Mann-Whitney U test was performed to verify the difference between the two groups according to sex. Significance level (α) of all the statistical analyzes were set to .05. The results obtained in this study are the knee joint torsional moment during roundhouse kick did not show any differences according to sex. The counter-clock wise torsional moment showed larger in supporting leg near the moment of hitting the target, and the clock wise torsional moment showed larger in kicking leg. 본 연구의 목적은 태권도 겨루기선수들이 몸통돌려차기를 수행할 때 무릎관절의 안정성을 유지하기 위해 기능하는 인대 및 반월상연골에 작용하는 비틀림 모멘트(torsional moment)를 역동역학적 기법으로 분석하는 것이다. 연구를 위해 표집 된 대상자들은 오른발을 주 사용발로 하는 남자 겨루기선수 8명과 여자 겨루기선수 8명이며, 성별에 따라 두 집단으로 구성하였다. 몸통돌려차기 동작은 14대의 T160 적외선 카메라와 AMTI force platform(OR-6) 2대로 구성된 Vicon MX System을 이용하여 각 마커의 위치정보와 지면반력 데이터를 수집한 후 Kwon3D XP를 통해 무릎관절의 joint torsional moment를 산출하였다. 모든 데이터는 분석을 위해 설정된 이벤트 시점에 따라 표준화 하였으며, 산출된 moment는 체중(BW)과 다리길이(LL)의 곱으로 표준화하였다. 본 연구에서 수집된 자료는 SPSS 23.0을 이용하여 각 집단별 기술통계량을 제시하였으며 성별에 따른 두 집단 간 차이를 검증하기 위하여 Mann-Whitney U test를 수행하였고 유의수준(α)은 .05로 설정하였다. 본 연구의 결과, 몸통돌려차기 시 무릎관절에 작용하는 joint torsional moment는 모든 무릎관절에서 성별의 차이가 나타나지 않았으며, 버팀다리의 무릎관절에는 반시계방향의 비틀림 모멘트가 목표물의 타격순간에 인접하여 크게 나타났다. 차는다리의 무릎관절에는 시계방향의 비틀림 모멘트가 크게 나타났다.

Moment Gradient Factor for Lateral Torsional Buckling Strength of Monosymmetric Stepped I-beam Subjected to Uniform Moment

Kathleen Mae Gelera,박종섭 한국방재학회 2010 한국방재학회논문집 Vol.10 No.2

Stepped I-beams having increased moment of inertia at one end (singly stepped beam) or both ends (doubly stepped beams) can often be seen in construction of bridges due to material economy and easy fabrication of the section. This paper presents the results of the parametric study of lateral torsional buckling of monosymmetric stepped I-beams with constant depth subjected to uniform moment. Design recommendations were made based on the finite element results of the models having different combinations of monosymmetric ratio, stepped length ratio, flange thickness ratio and flange width ratio. The proposed approximation is acceptable based on the parameters given having mostly conservative results. The proposed equation can be further used to extend the study to different loading conditions.

Semi analytical solutions for flexural-torsional buckling of thin-walled cantilever beams with doubly symmetric cross-sections

Gilbert Xiao,Silky Ho,John P. Papangelis 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.6

An unbraced cantilever beam subjected to loads which cause bending about the major axis may buckle in a flexuraltorsional mode by deflecting laterally and twisting. For the efficient design of these structures, design engineers require a simple accurate equation for the elastic flexural-torsional buckling load. Existing solutions for the flexural-torsional buckling of cantilever beams have mainly been derived by numerical methods which are tedious to implement. In this research, an attempt is made to derive a theoretical equation by the energy method using different buckled shapes. However, the results of a finite element flexural-torsional buckling analysis reveal that the buckled shapes for the lateral deflection and twist rotation are different for cantilever beams. In particular, the buckled shape for the twist rotation also varies with the section size. In light of these findings, the finite element flexural-torsional buckling analysis was then used to derive simple accurate equations for the elastic buckling load and moment for cantilever beams subjected to end point load, uniformly distributed load and end moment. The results are compared with previous research and it was found that the equations derived in this study are accurate and simple to use.

연속경간 하중을 받는 I형 스텝보의 비탄성 횡-비틀림 좌굴강도산정을 위한 모멘트 구배계수 연구

손지민,박종섭,Son. Ji-Min,Park. Jong-Sup 한국방재학회 2009 한국방재학회논문집 Vol.9 No.4

본 논문은 등분포하중과 양끝단에 모멘트가 작용하는 계단식 변단면보(스텝보)의 비선형 횡-비틀림 좌굴에 대해 연구이다. 3차원 유한요소해석 프로그램인 ABAQUS(2007)와 회귀분석 프로그램 MINITAB(2006)이 단순보 경계조건을 가지고 있는 일단 또는 양단 변단면보의 설계 좌굴강도 산정식 개발에 적용되었다. 해석모델의 비지지길이 내 중앙부분의 플랜지는 폭 30.48cm, 두께 2.54cm로 고정되었으며, 양단 또는 일단 플랜지의 크기는 해석매개변수로 고려되었다. 양단 스텝보는 플랜지 해석매개변수를 고려하여 27개, 일단 스텝보는 36개의 해석모델이 하나의 하중조건에 적용되었다. 본 연구는 잔류응력과 초기변형을 고려하여 비탄성 구간 내 3가지 비지지길이와 5가지 하중조건이 고려된 총 945개의 해석모델을 고려하였다. 잔류응력의 분포는 Pi와 Trahair(1995)가 적용한 분포도를 사용하였으며, 초기변형은 현대제철의 제작기준인 형강길이의 0.1%조건을 적용하였다. 본 논문에 제안된 식과 유한요소해석결과를 비교분석한 결과 양단 스텝보에서는 최대 13%, 일단 스텝보에서는 최대 10%의 차이를 보이고 있다. 본 연구를 통해 개발된 식은 경제적이고 합리적인 설계에 적극활용 가능하며, 변단면 부재의 비탄성 좌굴강도 연구에 크게 기여할 것이다. This paper investigates inelastic lateral-torsional buckling of stepped beams subjected to uniformly distributed load and end moments. A three-dimensional finite-element program ABAQUS (2007) and a regression program MINITAB(2006) were used to analytically develop new design equation for singly and doubly stepped beams with simple boundary condition. The flanges of the smaller cross-section in the stepped beams were fixed at 30.48 by 2.54 cm, whereas the width and thickness of the flanges of the larger cross-section varied. The web thickness and height of the beams were kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beam are considered with analytical parameters. Two groups of 27 cases and 36 cases, respectively, were analyzed for doubly and singly stepped beams in the inelastic buckling range. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. The distributions of residual stress of the cross-section is same as shown in Pi and Trahair (1995) and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The comparisons between results from proposed equations and the results from finite element analyses were presented in this paper. The maximum differences of two results are of 13% for the doubly stepped beam and 10% for the singly stepped beam. The proposed equations definitely improve current design methods for the inelastic lateral-torsional buckling problem and increase efficiency in building and bridge design.

The Effect of Stiffener on Behavior of Reduced Beam Section Connections in Steel Moment-Resisting Frames

M. Tahamouli Roudsari,F. Abdollahi,H. Salimi,S. Azizi,A. R. Khosravi 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4

Reduced Beam Section (RBS) connections are a new type of connection which have been used in steel moment-resisting frames since the 1994 Northridge earthquake. This study is primarily aimed at analyzing the effects of suitable web stiffeners on preventing the deterioration effect of the hysteresis curve for RBS connections. Results of more than 183 nonlinear finite element analyses on different IPE sections with radius cut, straight cut, and drilled-flange RBS connection showed that different web stiffeners considerably contribute to the enhancement of seismic performance of RBS connections. In this research, the effects of factors such as the geometry and the number of the stiffeners, the distance between the stiffener and column side, and the length and thickness of the stiffener on the seismic performance of RBS connections were also studied.

Delamination analysis of inhomogeneous viscoelastic beam of rectangular section subjected to torsion

Victor I. Rizov Techno-Press 2023 Coupled systems mechanics Vol.12 No.1

This paper considers a delamination analysis of a statically undetermined inhomogeneous beam structure of rectangular section with viscoelastic behavior under torsion. The beam is built in at its two ends. The beam has two longitudinal inhomogeneous layers with a delamination crack between them. A notch is made in the upper crack arm. The external torsion moment applied on the beam is a function of time. Under these conditions, the beam has one degree of indeterminacy. In order to derive the strain energy release rate, first, the static indeterminacy is resolved. Then the strain energy release rate is obtained by analyzing the balance of the energy with considering the viscoelastic behavior. The strain energy release rate is found also by analyzing the compliance of the beam for checkup. Solution of the strain energy release rate in a beam without a notch in the upper crack arm is derived too. In this case, the beam has two degrees of static indeterminacy (the torsion moment in the upper crack arm is treated as an additional internal redundant unknown). A parametric investigation of the strain energy release rate is carried-out.

컨테이너선의 최종 비틀림강도에 관한 연구

백점기,박영일,Pedersen, P.T.,Thayamballi, A.K. 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

개단면을 가진 박육보는 폐단면보에 비해 비틀림 강서이 극히 작기 때문에 비틀림 모멘트이 작용시에 크게 비틀려지고, 워핑현상이 생기게 되어 처음에 평면상태에 있던 횡단면은 더 이상 평면을 유지할 수 없게 된다. 따라서, 컨테이너 선박처럼 큰 갑판 개구부를 가진 선박의 구조설계시에는 워핑효과에 대한 분석이 필수 불가결하다. 특히 최종강도를 기준으로 한 컨테이너선박의 구조 안전성평가를 위해서는 비틀림 모멘트 작용시 발생하는 워핑현상이 선각의 최종강도에 어떠한 영향을 미치는지 분석하는 것이 극히 중요하다. 본 연구의 목적은 큰 갑판개구부를 가진 대형 컨테이너 선박의 최종비틀림강도 특성을 분석하는 것이다. 이를 위해 개단면을 가진 박육보에 비틀림 모멘트가 작용할 때 워핑현상의 발생특성을 이론적으로 분석하기 위하여 대표적인 컨테이너 선박의 횡단면에 대해 단위 크기의 비틀림 모멘트가 작용할 때의 워핑응력 및 전단응력분포를 계산한다. 또한, 4,300 TEU급 대형 컨테이너 선박을 대상으로 이상화구조요소법을 바탕으로 개발된 ALPS/HULL 프로그램을 이용하여 비틀림 모멘트가 작용할 때의 최종강도 붕괴특성을 분석한다. The aim of the present study is to investigate the ultimate strength characteristics of ship hulls with large hatch openings under torsion. Axial (warping) as well as shear stresses are normally developed for thin-walled beams with open cross sections subjected to torsion. A procedure for calculating these stresses is briefly described. As an illustrative example, the distribution and the magnitude of warping and shear stresses for a typical container vessel hull cross section unde unit torsion are calculated by the procedure. As part of this tudy, the special purpose non-linear finite element program ALPS/HULL for efficient analysis of the ultimate strength of ship hulls has been developed based on the idealized structural unit method (ISUM). Using the ALPS/HULL program, the progressive collapse behavior of a hypothetical container vessel under torsion is analyzed.

설계풍하중 스펙트럼 하중재생에 의한 건축 구조물의 시간이력 해석

황재승,이상현,하영철 한국풍공학회 2015 한국풍공학회지 Vol.19 No.2

현재 사용되고 있는 대부분의 풍진동해석법은 진동수영역의 스펙트럼 해석법에 기초하고 있다. 스펙트럼해석법은 하중 및 응답의 위상각을 무시하게 되며 그에 따라 병진방향 및 비틀림 방향의 모드 응답조합이 어려워질 수 있다. 본 연구에서는 일반화 밑면 모멘트 스펙트럼밀도함수로부터 재생된 풍하중 시간이력을 이용하여 병진, 비틀림 방향이 연계된 구조물의 응답을 해석하는 시간이력 해석법에 대해서 다룬다. 제시된 시간이력 해석법의 적용성을 검토하기 위하여 직사각형 평면을 가지는 40층 규모의 구조물을 대상으로 해석을 수행하였다. 수치해석결과에 의하면, 시간이력해석법에 의하여 질량중심으로부터 멀리 떨어진 곳의 비틀림 모드에 의한 응답특성을 파악할 수 있었으며, 병진방향과 비틀림방향 모드 응답의 조합에 의하여 보다 정확한 응답예측이 가능한 것을 알 수 있었다. 또한 해석된 응답을 이용하여 사용성능 및 처짐 성능평가를 수행할 수 있기 때문에 예비설계 단계에서 보다 정밀한 내풍 성능평가가 가능한 것을 알 수 있었다. Current wind engineering practice is based on the spectrum analysis in frequency domain which ignores the phase information of wind load and structural responses so that it has a limitation on the development of combination of wind-induced translational responses coupled with rotational responses. In this study, a time history analysis process is developed to analyze the responses of high-rise building, which the translational and torsional responses are strongly coupled, using the wind loads generated from the generalized power spectrum density of base moment. For the evaluation of the applicability of the process, numerical analysis is performed for 40 story steel frame structure with rectangular section plan. From the numerical results, it is found that the response at the point far away from a mass center is strongly coupled with torsional mode, and the acceleration and displacement responses can be estimated more accurately by the combination of the lateral and torsional mode responses. In addition, the evaluation for the serviceability and the deflection condition can be effectively predicted using the analyzed responses in schematic design phase.

Unified theory of reinforced concrete-A summary

Hsu, Thomas T.C. Techno-Press 1994 Structural Engineering and Mechanics, An Int'l Jou Vol.2 No.1

A unified theory has recently been developed for reinforced concrete structures (Hsu 1993), subjected to the four basic actions - bending, axial load, shear and torsion. The theory has five components, namely, the struts-and-ties model, the equilibrium (or plasticity) truss model, the Bernoulli compatibility truss model, the Mohr compatibility truss model and the softened truss model. Because the last three models can satisfy the stress equilibrium, the strain compatibility and the constitutive laws of materials, they can predict not only the strength, but also the load-deformation history of a member. In this paper the five models are summarized to illustrate their intrinsic consistency.

RC보의 극한비틀림강도 중 콘크리트의 비틀림강도에 대한 이론적 연구

박창규 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

Modified compression field theory is already applied in shear problem at some code(AASHTO-1998) partly. Nominal shear strength of concrete beam is sum of concrete shear strength and steel shear strength in the current design code. But the torsional moment strength of concrete is neglected in calculation of the nominal torsional moment strength of reinforced concrete beam in current revised code. Tensile stress of concrete strut between cracks is still in effect due to tension stiffening effect. But The tensile stresses of concrete after cracking are neglected in bending and torsion in design code. Torsional behavior is similar to shear behavior in mechanics. Therefore the torsional moment strength of concrete should be concluded in the nominal torsional moment strength of reinforced concrete beam. This paper shows that the torsional moment strength of concrete is caused by the average principal tensile stress of concrete. To verify validity of the proposed model, the nominal torsional moment strengths according to two ACI codes (89, 02) and the proposed model are compared to experimental torsional moment strengths of 55 test specimens found in literature. The torsional moment strengths by the proposed model show the best results.