• Structural Engineering and Mechanics
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• 제41권4호
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• pp.459-477
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• 2012

This paper attempts to determine the inclination of the compression strut within variable angle truss models for RC beams loaded in shear-flexure through a proposed semi-analytical approach. A truss unit is used to analyze a reinforced concrete beam, by the principle of virtual work under the truss analogy. The inclination of the compression strut is then theoretically derived. The concrete contribution is addressed by utilizing the compatibility condition within each truss unit. Comparisons are made between the predicted and published experimental results of the seventy one RC beams with respect to the shear strength and the inclined angle of the compression strut at this state to investigate the adequacy of the proposed semi-analytical approach.

• Archives of Plastic Surgery
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• 제40권5호
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• pp.616-620
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• 2013

Background Nasal tip support is an essential consideration for rhinoplasty in East Asians. There are many techniques to improve tip projection, and among them, the columellar strut is the most popular technique. However, the conventional design is less supportive for rotating the tip. The amount of harvestable septal cartilage is relatively small in East Asians. For an optimal outcome, we propose an L-shaped design for applying the columellar strut. Methods To evaluate the anthropometric outcomes, the change in nasal tip projection and the columella-labial angle were analyzed by comparing preoperative and postoperative photographs. The anthropometric study group consisted of 25 patients who underwent the same operative technique of an L-shaped strut graft using septal cartilage and were followed up for more than 9 months. Results There were statistically significant differences between the preoperative and postoperative values in the nasal tip projection ratio and columella-labial angle. We did not observe any complications directly related to the L-shaped columellar strut in the anthropometric study group. Conclusions The L-shaped columellar strut has advantages not only in the controlling of tip projection and rotation, but in that it needs a smaller amount of cartilage compared to the conventional septal extension graft. It can therefore be an alternative technique for nasal tip plasty when there is an insufficient amount of harvestable septal cartilage.

• Computers and Concrete
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• 제28권6호
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• pp.621-634
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• 2021

For the reliable strut-and-tie model (STM) design of disturbed regions of concrete members, structural designers must accurately determine the strength of concrete struts to check the strength conditions of a selected STM el and the anchorage of reinforcing bars in nodal zones. In this study, the author proposed a consistent numerical method for strut strength, applicable to all two-dimensional STMs. The proposed method includes the effects of a biaxial stress state associated with tensile strains in reinforcing bars crossing a strut, deviation angle between strut orientation and compressive principal stress flow, and degree of confinement provided by reinforcement. The author examined the method's validity through the STM prediction of the ultimate strengths of 517 reinforced concrete (RC) deep beams, 24 RC panels, and 258 RC corbels, all tested to failure.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.123-130
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• 2010

본 논문에서는 기존 건축물의 내진성능을 향상시키기 위해 시공성과 설치 비용적인 측면에서 상대적으로 우수한 강재댐퍼를 대상으로 기존 개발된 장치와 새로 개발된 형상의 장치에 대한 평가를 해석적으로 수행하였다. 해석결과는 강도 및 에너지 소산능력으로 평가하였으며, 제안된 내력 산정식의 적용을 아울러 평가하였다. 연구대상 댐퍼의 스트럿 형상은 V형, S형이며, 댐퍼의 스트럿 높이와 각도를 주요 변수로 한 후 ABAQUS를 이용하여 유한요소 해석하였다. 해석은 최대변위를 50mm로 하고 점진적인 이력변위곡선을 적용하여 수행하였다. 항복강도, 최대강도, 에너지 소산능력 평가결과, V형 및 S형 모두 우수한 성능을 보유한 것으로 평가되었으며, 또한 스트럿 각도 $60^{\circ}$ 및 높이 140, 200 mm의 성능이 안정적인 것으로 평가되었다. 전체적으로는 S형의 응답이 V형보다 안정적인 것으로 평가되어, S형 강재댐퍼의 적용성이 V형보다 유리한 것으로 평가되었다.

• 대한조선학회논문집
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• 제33권1호
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• pp.27-39
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• 1996

잠수체(strut)에 부착된 핀(fin)의 자유표면 효과를 회류수조를 사용하여 실험적으로 연구하였다. 본 연구에서는 주로 유속(V), 핀의 앙각(${\alpha}$)과 핀의 몰수깊이 대 현장비, 즉 몰수비(H/C)에 따른 핀의 양력을 축정하였으며, 지주가 없는 핀만의 양력을 측정하여 지주에 부착된 핀의 양력과 비교함으로써 핀에 미치는 지주의 영향도 관찰하였다. 유동가시화를 통하여 지주만 있을 때와 핀이 부착되어 있을 때의 앙각에 따른 자유표면의 변화를 조사하였다. 이와 같은 실험들은 대체로 몰수비가 작은 영역을 중심으로 수행되었다. 본 연구의 결과로는 핀의 양력계수(CL)는 작은 몰수비(H/C<3.0)의 경우 자유표면의 영향을 크게 받으며, 큰 몰수비(H/C>5.0)인 경우는 자유표면의 영향을 거의 무시할 수 있다. 작은 몰수깊이에서 핀의 유입앙각도 지주와 유속에 의해 크게 영향을 받는다. 자유표면의 변형은 지주에 의한 조파현상이 지배적인 역할을 하고 있으나 핀의 몰수깊이가 작을 경우는 핀의 영향도 크게 작용한다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.254-262
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• 2011

본 연구의 목적은 슬릿형 강재댐퍼보다 에너지 소산능력 등이 우수할 것으로 예상되는 V형 강재 댐퍼 개발에 있다. 이를 위하여 댐퍼 스트럿의 높이 및 각도에 대한 실험체 9개를 만들어 전단실험을 수행하였다. 실험결과, 스트럿 높이가 270mm이고, 스트럿 각도 $60^{\circ}$인 경우의 V형 강재댐퍼가 가장 우수한 내진성능 보유한 것으로 평가되었다. 또한 기존내력식을 이용한 댐퍼의 항복강도를 비교한 결과, 기존 실험결과를 분석한 범위 내에서 V형 댐퍼의 실험결과가 높게 평가되는 것으로 나타났다.

• 한국농공학회지
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• 제38권5호
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• pp.140-154
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• 1996

In this study, displacement, deformation, and stability according to change of cohesion and internal friction angle were investigated through elasto-plastic method, finite-element method, and in-site experiment when excavating soft ground using sheet pile. The results of the study were as follows : 1. The horizontal displacement was 5.5% of the excavation depth by the elasto-plastic method and 3.9% of the excavation depth by the on-site experiment at the final excavation depth(GL-8.Om) on the condition of double stair strut after excavating GL-6.Om. 2. Relationships between cohesion(c) and internal friction angle $({\varphi})$ when safety factor to the penetration depth was 1.2 is shown in the following equations : (a) c= -O.0086$({\varphi})$+ O.3(D=3m) and (b) c=-0.00933$({\varphi})$+0.14(D=4m). 3. The results of elasto-plastic method and the experiment show that possible excavation depth was GL-6.Om after setting single stair strut in a short period in terms of possibility of carrying out on the condition of experimental site on the contrary general reinforcement method, setting double stair strut after excavating GL-4.0m. 4. After setting the strut, distribution of the horizontal displacement had concentrated on the excavation base and possible local failure which the shear strain caused decreased by the strut reinforced. 5. After setting strut, displacement of sheet pile was decreased by half, the limit of stable excavation depth of ground was GL-8.Om, and the maximum horizontal displacement at the GL-8.Om was 1.6% of excavation depth by the elasto-plastic method, 0.7% of excavation depth by the finite-element method.

• Structural Engineering and Mechanics
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• 제73권5호
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• pp.515-527
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• 2020

This paper presents a stress field approach for the shear capacity of stirrup-reinforced concrete beams that explicitly incorporates the contribution of principal tensile stresses in concrete. This formulation represents an extension of the variable strut inclination method adopted in the Eurocode 2. In this model, the stress fields in web concrete consist of principal compressive stresses inclined at an angle θ combined with principal tensile stresses oriented along a direction orthogonal to the former (the latter being typically neglected in other formulations). Three different failure mechanisms are identified, from which the strut inclination angle and the corresponding shear strength are determined through equilibrium principles and the static theorem of limit analysis, similar to the EC-2 approach. It is demonstrated that incorporating the contribution of principal tensile stresses of concrete slightly increases the ultimate inclination angle of the compression struts as well as the shear capacity of reinforced concrete beams. The proposed stress field approach improves the prediction of the shear strength in comparison with the Eurocode 2 model, in terms of both accuracy (mean) and precision (CoV), as demonstrated by a broad comparison with more than 200 published experimental results from the literature.

• Steel and Composite Structures
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• 제21권5호
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Clinics in Shoulder and Elbow
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• 제20권2호
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• pp.95-99
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• 2017

Background: The purpose of this study was to investigate the clinical and radiological outcomes of locking plate fixation with fibular strut allograft to manage unstable osteoporotic proximal humerus fractures. Methods: We retrospectively reviewed 15 patients who underwent open reduction and locking plate fixation with fibular strut allograft for osteoporotic proximal humerus fracture between July 2011 and June 2015. For functional evaluation, we evaluated visual analogue scale (VAS) pain score, American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, and active range of motion. For radiological evaluation, shoulder true anteroposterior (AP) and AP in $20^{\circ}$ external rotation, as well as the axillary view were taken at two weeks, six weeks, three months, six months, and one year. And the neck-shaft angle was measured on the AP view in $20^{\circ}$ external rotation view. Results: At the one-year follow-up, mean VAS pain score and all shoulder scores, including ASES score and UCLA shoulder score, exhibited satisfactory clinical outcomes. All patients obtained bone union between three and six months post-procedure. Moreover, the mean immediate postoperative neck-shaft angle was $138^{\circ}{\pm}4^{\circ}$, and at one-year follow-up, the neck shaft angle was $137^{\circ}{\pm}5^{\circ}$. There was no significant difference between the preoperative and postoperative values (p=0.105). Conclusions: For the unstable two-part and three-part osteoporotic proximal humerus fractures with medial calcar comminution, the use of fibular strut allograft with locking plate fixation was effective in maintaining the initial status of reduction and exhibiting the satisfactory functional and radiological outcomes.