• Coupled systems mechanics
• /
• 제12권1호
• /
• pp.69-81
• /
• 2023

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.

• Structural Engineering and Mechanics
• /
• 제90권5호
• /
• pp.505-515
• /
• 2024

In this study, obtaining theoretical stress-strain curves and determining the parameters defining the equivalent rectangular stress block were aimed for 3 and 4-layered rectangular Reinforced Concrete (RC) cross-sections subjected to flexure. For these aims, the analytical stress-strain model proposed by Hognestad was chosen for the concrete grades (20 MPa≤fck≤60 MPa) used in this study. The tensile strength of the concrete was neglected and the thickness of the concrete layers in the compression zone of the concrete cross-section was taken as equal. In addition, while concrete strength was kept constant within each layer, concrete strengths belonging to separate layers were increased from the neutral axis towards the outer face of the compression zone of the concrete cross-section. After the equivalent rectangular stress block parameters were determined by numerical iterations, variations of these parameters depending on concrete strength in layers and layer numbers were obtained. Finally, some analytical equations have been proposed to predict the equivalent stress block parameters for the 3 and 4-layered RC cross-sections and validities of these proposed equations were shown by different metrics in this study.

• Steel and Composite Structures
• /
• 제43권3호
• /
• pp.341-351
• /
• 2022

This paper presents an inelastic buckling behavior analysis of rectangular hollow steel tubes with geometrical imperfections under elevated temperatures. The main variables are the temperature loads, slenderness ratios, and exposure conditions at high temperatures. The material and structural properties of steels at different temperatures are based on Eurocode (EN 1993-1-2, 2005). In the elastic buckling analysis, the buckling strength decreases linearly with the exposure conditions, whereas the inelastic buckling analysis shows that the buckling strength decreases in clusters based on the exposure conditions of strong and weak axes. The buckling shape of the rectangular steel column in the elastic buckling mode, which depicts geometrical imperfection, shows a shift in the position at which bending buckling occurs when the lower section of the member is exposed to high temperatures. Furthermore, lateral torsional buckling occurs owing to cross-section deformation when the strong axial plane of the model is exposed to high temperatures. The elastic buckling analysis indicates a conservative value when the model is exposed to a relatively low temperature, whereas the inelastic buckling analysis indicates a conservative value at a certain temperature or higher. The comparative results between the inelastic buckling analysis and Eurocode 3 show that a range exists in which the buckling strength in the design equation result is overestimated at elevated temperatures, and the shapes of the buckling curves are different.

• Structural Engineering and Mechanics
• /
• 제44권2호
• /
• pp.239-255
• /
• 2012

This work presents a contribution to understand the inverted trussed beams behavior. The system has a main beam and struts with rectangular cross section associated to a wire rope enlaced to the main beam. It is an unpublished system with the advantage of easy positioning of the wire rope, once it is a continuous and connected by turnbuckles. It is a system that can be used as support for concrete formworks or for rehabilitation wooden beams proposal. The enlacement of the cable demands a small notch at the top of the cross section and a cross pin at the bottom. Six inverted trussed beams were tested, with spans of 180 cm with cables diameter of 1/4". Additionally, four simple beams without any external steel cable were also tested with material from the same lot of wood, allowing a comparison in rupture. The results showed capacity gain of around 60% compared to a simple beam. Once the wire rope characteristics and anchoring are very important for structure response, some improvement suggestions for the efficiency of the cables are also presented.

• 오토저널
• /
• 제3권3호
• /
• pp.24-29
• /
• 1981

This paper is studied an efficient temperature distribution and heat transfer of two-dimensional rectangular cross-section by the higher-order triangular finite dynamic element and finite difference. This is achieved by employing a discretization technique based on a recently developed concept of finite dynamic elements, involving higher order dynamic correction terms in the associated stiffness and convection matrices. Numerical solution results of temperature distribution presented herein clearly optimum element and show that FEM10 is the most accurate temperature distribution, but heat transfer and computational effort is the most acquired.

• 한국수자원학회논문집
• /
• 제37권7호
• /
• pp.527-540
• /
• 2004

다중 만곡부에서의 주흐름과 이차류의 흐름 특성을 분석하기 위하여 중심각 120$^{\circ}$인 두 개의 만곡부로 이루어진 사행수로에서 실험을 수행하였다. 실험수로의 횡단면은 직사각형과 곡선형 두 가지 형태로 제작하였으며, 곡선형 단면 형상 결정에는 베타함수를 이용하였다. 3차원 유속장의 측정은 micro-ADV를 이용하였다. 실험결과, 직사각형 수로에서 주흐름은 수로의 가장 짧은 경로를 따라 발생하였으며, 이는 기존 연구자들의 결과와 일치한다. 곡선형 수로에서도 주흐름이 직사각형 수로에서의 주흐름의 거동과 비슷한 양상을 보이는 것으로 밝혀졌다. 곡선형 수로에서의 실험결과가 실제 자연하천의 만곡부에서의 주흐름 거동(최심선을 따라 발생)과 상이하게 나타나는 이유는 실험수로의 바닥 조도와 사행도에 기인한 것으로 사료된다. 이차류의 정량적인 분석을 위하여 흐름함수를 도입한 결과, 만곡부에서 주 셀 뿐만 아니라 바깥제방 셀의 위치 및 형태를 확인할 수 있었다. 또한 이차류 강도를 계산한 결과, 직사각형 및 곡선형 수로에서 최대값은 두 번째 만곡부의 정점 부근에서 가장 크게 나타나며 곡선형 수로의 이차류의 강도가 직사각형 수로의 값보다 크게 나타나고 있음을 알 수 있었다. 직사각형 수로의 경우, 하폭 대 수심비가 커질수록 이차류의 강도가 증가하고 있음을 확인하였다.

• Journal of Mechanical Science and Technology
• /
• 제17권2호
• /
• pp.207-214
• /
• 2003

The fatigue behaviour of six different hollow section T-joints subjected to out-of-plane bending moment was investigated experimentally using scaled steel models. The joints had circular brace members and rectangular chord members. Hot spot stresses and the stress concentration factors. (SCFs) were determined experimentally. Fatigue testing was carried out under constant amplitude loading in air. The test results have been statistically evaluated, and show that the experimental SCF values for circular-to-rectangular (CHS-to-RHS) hollow section joints were found to be below those of circular-to-circular (CHS-to-CHS) hollow section joints. The fatigue strength, referred to experimental hot spot stress, was in reasonably good agreement with referred fatigue design codes for tubular joints.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권4호
• /
• pp.141-148
• /
• 2000

Recently the Carbon Fiber Sheet(CFS) is widely used for strengthening damaged RC structures. Strengthening compression members such as column can increase ductility and strength due to the confinement effect. In this experiment, the behavior of concrete cylinders confined by CFS was examined. The confinement pressure is increased linearly as axial stress is increased in low axial stress, and the confinement effect of CFS was rapidly developed after near maximum axial stress, thus axial strength and ductility was improved. As the ratio of CPS is increased, concrete cylinders failed due to local fracture of CFS. The confinement effect of circular section is more efficient than that of rectangular section. And significant improvement of axial strength, axial strain, transverse strain at failure is observed in circular section. This is because in rectangular section the local fracture of CFS near corner may be occured, thus the strain efficiency ratio must be considered for RC structures with CFS.

• EDISON SW 활용 경진대회 논문집
• /
• 제5회(2016년)
• /
• pp.256-261
• /
• 2016

In this paper, Shape optimal design for a chair with 4 legs and 2 stretchers consisting of stainless steel was conducted. The shape was transformed by identifying stress and deformation for the part of leg and stretcher. In addition, load condition and mesh was designed using Hypermesh. The stress analysis was carried out using CSD_Elast that is one of EDISON program. In seat test, Maximum equivalent stress was showed at the contact part between seat and legs. As a result, a leg cross-section with rectangular and arch was designed. And optimal height of stretcher was found to reduce a deformation. Also, maximum deformation was reduced by designing a stretcher with ellipse cross-section. So, Optimal chair having 4 legs with rectangular cross section and 2 stretchers with ellipse cross section was shown to satisfy the safety ratio.

• 한국자동차공학회논문집
• /
• 제2권1호
• /
• pp.84-95
• /
• 1994

The effects of punch and blank shapes in the rectangular cup drawing process are examined experimentally to improve the formabilities. For this purpose, three blank shapes which are h-bl., G-bl., and T-bl., and five punch shape factors which are the ratios of two adjacent side lengths in rectangular cross section are adopted. The constructing methods of the three blank shapes are as follows. The h-bl. is designed by slip-line theory, and the G-bl. is selected for the similar shape to the punch. The T-bl. is obtained by the drawing method which is introduced in the technical references. The five punch shape factors are selected for length/width=1, 1.25, 1.5, 1.75 and 2. The experimental procedures are performed for all the above forming conditions to investigate and compare the formabilities. As a result, it is verified experimentally that the rectangular cups drawn by the h-bl. are more ideal than those drawn by G-bl. and T-bl.. They have not only higher limiting drawing ratio, more uniformity in drawn cup heights and more ideal thickness distributions, but also need relatively less maximum drawing forces.