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

• 한국초전도ㆍ저온공학회논문지
• /
• 제5권1호
• /
• pp.71-75
• /
• 2003

The conduit fer superconducting cable is welded and plastically deformed during the jacketing process to make the CICC (Cable-in-Conduit-Conductors) fer a fusion magnet. The jacketing process of KSTAR (Korea Superconducting Tokamak Advanced Research) conductors is composed of several sequential steps such as rounding, welding, sizing, and square-rolling. Since the welded zone in Incoloy 908 conduit is brittle and easy to have flaws, there may be a possibility of stress corrosion cracking during the heat treatment of coil when both the induced tensile residual stress and the concentration of oxygen in the furnace are sufficiently high. The steps of the jacketing process were simulated using the finite element method of the commercial ABAQUS code, and the stress distribution in the conduit in each step was calculated, respectively. Furthermore, the variations of residual welding stresses through the steps of the jacketing process were calculated and analyzed to anticipate the possibility of the stress corrosion cracking in the conduit. The concentrated high tensile residual welding stresses along the welding bead decrease by the plastic deformation of the following sizing step. The distribution in residual stresses in the conductor for magnet coil is mainly governed by the last step of square-rolling.

• 전기학회논문지
• /
• 제67권1호
• /
• pp.142-147
• /
• 2018

Private electrical facilities are judged whether it is suitable for the insulation aging condition of their incoming underground cables using DC leakage current test method. In the case where the service point of utility is the secondary side of cut out switch installed in the electric pole, there is a problem that it is difficult to separate the lightning arresters(LA) because of their high position of the pole. Therefore, the field test voltage is applied at value lower than DC 30 kV, which are stated in the inspection guideline. However, this test could reduced the insulation performance of the LA by accelerating the electrical stress of the metal oxide varistor element in the pre-breakdown region. In this study, we analyzed the relationship between the DC test voltage and the leakage current using the non-destructive DC high voltage equipment with leakage current measurement function. The results show that the leakage current increases sharply above the specified test voltage. As a consequence, it could be contributed to improve insulation aging inspection method by selecting the possible test area on the VI characteristic curve of the pre-breakdown area of the LA.

• Structural Engineering and Mechanics
• /
• 제18권5호
• /
• pp.591-607
• /
• 2004

The substance of the use of the derived non-linear creep constitutive equations under variable stress levels (see first part of the paper, Kmet 2004) is explained and the strategy of their application is outlined using the results of one-step creep tests of the steel spiral strand rope as an example. In order to investigate the creep strain increments of cables an experimental set-up was originally designed and a series of tests were carried out. Attention is turned to the individual main steps in the production and application procedure, i.e., to the one-step creep tests, definition of loading history, determination of the kernel functions, selection and definition of constitutive equation and to the comparison of the resulting values considering the product and the additive forms of the approximation of the kernel functions. To this purpose, the parametrical study is performed and the results are presented. The constitutive equations of non-linear creep of cable under variable stress history offer a strong tool for the real simulation of stochastic variable load history and prediction of realistic time-dependent response (current deflection and stress configuration) of structures with cable elements. By means of suitable stress combination and its gradual repeating various loads and times effects can be modelled.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
• /
• pp.537-544
• /
• 2003

This paper deals with stress corrosion cracking behavior of high strength steel exposed to marine environments. The objective is to determine the time to failure as a function of hydrogen concentration and tensile stress in the wires. A crack growth curve is modeled using finite element method (FEM) program. The coupled hydrogen diffusion-stress analyses of SCC were programmed separately. The first part is calculating stress and stress intensity /sup 1)/factor of a cylindrical shell, prestressing tendon or suspension bridge wires, from the initiation of cracks to rupture. Virtual crack extension method, contour integral method, and crack tip elements are used for the calculation of stresses in front of the crack tip. Comparisons of the result show a good agreement with the analytical equations and wire tests. The second part of the study deals with the programming of hydrogen diffusion, affected by hydrostatic stress, calculated at the location of boundary of plastic area around the crack tip. The results of paper can be used in the design and management of prestressed structures, cable stayed and suspension bridges. Time dependent correlated parallel reliabilities of a cable, composed of 36 wires, were evaluated by the consideration of the deterioration of stress corrosion cracking.

• Steel and Composite Structures
• /
• 제26권1호
• /
• pp.115-123
• /
• 2018

Steel-concrete composite structure is widely applied to bridge engineering due to their outstanding mechanical properties and economic benefit. This paper studied a new type of steel-concrete composite anchorage system for a self-anchored suspension bridge and focused on the mechanical behavior and force transferring mechanism. A model with a scale of 1/2.5 was prepared and tested in ten loading cases in the laboratory, and their detailed stress distributions were measured. Meanwhile, a three-dimensional finite element model was established to understand the stress distributions and validated against the experimental measurement data. From the results of this study, a complicated stress distribution of the steel anchorage box with low stress level was observed. In addition, no damage and cracking was observed at the concrete surrounding this steel box. It can be concluded that the composite effect between the concrete surrounding the steel anchorage box and this steel box can be successfully developed. Consequently, the steel-concrete composite anchorage system illustrated an excellent mechanical response and high reliability.

• International Journal of Precision Engineering and Manufacturing
• /
• 제5권4호
• /
• pp.50-60
• /
• 2004

A very flexible beam can be used to model various types of continuous mechanical parts such as cables and wires. In this paper, the dynamic properties of a very flexible beam, included in a multibody system, are analyzed using absolute nodal coordinates formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between a continuous large deformable beam and a rigid multibody system, a combined system equations of motion is derived by adopting absolute nodal coordinates and rigid body coordinates. Using the derived system equation, a computation method for the dynamic stress during flexible multibody simulation is presented based on Euler-Bernoulli beam theory, and its reliability is verified by a commercial program NASTRAN. This method is significant in that the structural and multibody dynamics models can be unified into one numerical system. In addition, to analyze a multibody system including a very flexible beam, formulations for the sliding joint between a very deformable beam and a rigid body are derived using a non-generalized coordinate, which has no inertia or forces associated with it. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example.

• Structural Engineering and Mechanics
• /
• 제37권3호
• /
• pp.309-320
• /
• 2011

As a new type of large-span space structure, suspendome is composited of the upper single-layer reticulated shell and the lower cable-strut system. It has better mechanical properties compared to single-layer reticulated shell, and the overall stiffness of suspendome structure increases greatly due to the prestress of cable. Consequently, it can cross a larger span reasonably, economically and grandly with high rigidity, good stability and simple construction. For a better assessment of the advantages of mechanical characteristic of suspendome quantitatively, the static behavior of Kiewitt6 suspendome was studied by using finite element method, and ADINA was the software application to implement the analysis. By studying a certain suspendome, the internal forces, deformation and support constrained forces of the structure were obtained in this paper. Furthermore, the influences of parameters including prestress, stay bar length, cross-sectional area and rise-to-span ratio were also discussed. The results show that the increase of prestress and vertical stay bar length can improve the stiffness of suspendome; Cross-sectional area has nearly no impact on the static behavior, and the rise-to-span ratio is the most sensitive parameter.

• 한국해양공학회지
• /
• 제26권5호
• /
• pp.18-24
• /
• 2012

This paper concerned with the behaviour of shaping formation and the erection for SCST structure by cable-tensioning for three kinds of structure models. The joint types of experimental models are ball type joints, bolt type joints with gusset plates, and bolt type joints. The feasibility of the proposed shaping method and the reliability of the established geometric model were confirmed with a nonlinear finite element analysis and an experimental investigation for full size scaled pyramid test model and three kinds of SCST structure models. The characteristic of the behaviour of each joint type is shown in the shaping test for practical design purposes. As a results, the behaviour characteristics of joints is very significant in shaping analysis of space structures. So the joint type should be considered in the design and analysis of the shape formation for space structures. Also, in the special field condition, it could be a fast and economical method for constructing the space structure.

• Journal of Information Processing Systems
• /
• 제14권1호
• /
• pp.270-279
• /
• 2018

PCI Express (PCIe) bus, which was only used as an internal I/O bus of a computer system, has expanded its function to outside of a system, with progress of PCIe switching processor. In particular, advanced features of PCIe switching processor enable PCIe bus to serve as an interconnection network as well as connecting external devices. As PCIe switching processors more advanced, it is required to consider the different adapter card architecture. This study developed multipurpose adapter cards by applying an on-board optical module, a latest optical communications element, in order to improve transfer distance and utilization. The performance evaluation confirmed that the new adapter cards with long cable can provide the same bandwidth as that of the existing adapter cards with short copper cable.