• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.765-784
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• 2015

Connections are usually designed either as pinned usually associated with simple construction or rigid normally is associated with continuous construction. However, the actual behaviour falls in between these two extreme cases. The use of partial strength or semi-rigid connections has been encouraged by Euro-code 3 and studies on semi-continuous construction have shown substantial savings in steel weight of the overall construction. Composite connections are proposed in this paper as partial or full strength connections. Standardized connection tables are developed based on checking on all possible failure modes as suggested by "component method" for beam-to-column composite connection on major axis. Four experimental tests were carried out to validate the proposed standardised connection table. The test results showed good agreement between experimental and theoretical values with the ratio in the range between 1.06 to 1.50. All tested specimens of the composite connections showed ductile type of failure with the formation of cracks occurred on concrete slab at maximum load. No failure occurred on the Trapezoidal Web Profiled Steel Section as beam and on the British Section as column.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.149-158
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• 2003

It is customary that tendons and sectional dimensions are calibrated and tendon forces are applied at once at the initial stage to keep the subsequent stresses occuring at different loading stages within the allowable stresse in prestressed concrete (PSC) bridge design. However, this traditional tensioning method usually results in a too conservative sectional depth in view of ultimate capacity of a girder. A new design method which can realize the reduction of sectional depth of PSC girder is theoretically suggested in this study. Tendons are tensioned twice at different loading stages: the initial stage and the stage after fresh slab concrete is cast. It can be shown that according to this technique, sectional depth can be significantly reduced and larger span can be realized compared to traditional ones. In this paper, there is an example about the design of bridge by means of new PSC design theory, having a longer span than a existing railway bridge. Also, a new method by continuous tendon profiles is presented to be continuous a IPC bridge.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.84-94
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• 1996

In order to prevent shell sticking by providing sufficient lubrication between the strand and the mold, the mold oscillation has been used. Now it is well known that the shape of the oscillation curve has a decisive effect on the surface quality of the cast product. Besides, oscillation parameters such as stroke and frequency are also very important. In order to guarantee that parameters which have been found to be optimal for a certain grade of steel do not change with time, periodical checks of the physical condition of the whole equipment are necessary. The portable mold oscillation analyzer with integrated computer, developed by POSCO, records the movement of the mold in every spatial direction. The system uses the gap sensors to measure the mold movement (displacement ) in the two horizontal directions according to the mold narrow and broad faces and the vertical strokes in the four corners of mold. The gap sensor is a non-contacting minute displacement measuring device using the principle of high frequency eddy current loss. The mold oscillation diagnosis system integrates the gap sensors, their converters and the industrial portable computer with plug-in data acquisition boards. The all programs, such as the fast Fourier transformation module (amplitude and phase spectrums) and harmonic analysis module, was coded by LabVIEW$^{TM}$ software as the graphical language. In an own 'expert module' which is included in the diagnosis program, one can obtain much information about the mold oscillation equipment.

• Structural Engineering and Mechanics
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• v.47 no.5
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• pp.661-678
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• 2013

As a new type of vibration reduction, the ladder track system has been successfully used in engineering. In this paper, a numerical model of the train-track-viaduct system is established to study the dynamic responses of an elevated bridge with ladder track. The system is composed of a vehicle submodel, a track submodel and a bridge submodel, with the measured track irregularities as the system self-excitation. The whole time histories of a train running through an elevated bridge with $3{\times}27m$ continuous PC box girders are simulated. The dynamic responses of the bridge such as deflections, lateral and vertical accelerations, and the vehicle responses such as derailment factors, offload factors and car-body accelerations are calculated. The calculated results are partly validated through the comparison with the experimental data. Compared to the common slab track, adapting the ladder sleeper can effectively reduce the accelerations of the bridge girder, and also reduce the car-body accelerations and offload factors of the train vehicle.

• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.51-59
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• 2013

The use of light-gauge steel framing in low-rise commercial and industrial building construction has experienced a significant increase in recent years. In such construction, the wall framing is an assembly of cold-formed steel (CFS) studs held between top and bottom CFS tracks. Current construction methods utilize heavy hot-rolled steel sections, such as steel angles or hollow structural section tubes, to transfer the load from the end seats of the floor joist and/or from the load-bearing wall studs of the stories above to the supporting load-bearing wall below. The use of hot rolled steel elements results in significant increase in construction cost and time. Such heavy steel elements would be unnecessary if the concrete slab thickening on top of the CFS wall can be made to act compositely with the CFS track. Composite action can be achieved by attaching stand-off screws to the track and encapsulating the screw shank in the deck concrete. A series of experimental studies were performed on full-scale test specimens representing concrete/CFS flexural elements under gravity loads. The studies were designed to investigate the structural performance of concrete/CFS simple beams and concrete/CFS continuous headers. The results indicate that concrete/CFS composite flexural elements are feasible and their structural behavior can be modeled with reasonable accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.612-615
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• 1996

In the continuous casting process, molten metal contacts the mold wall and the molten metal surface is subject to the mold oscillation. The mold oscillation results in the oscillation marks on the surface of solidified steel, which has undesirable effects on the quality of slabs. In order to reduce the oscillation marks by achieving soft contact of molten metal with the mold surface, alternating magnetic field is applied to the surface of molten metal. However, if the magnetic field strength becomes too strong, the melt flow induced by the magnetic field. causes the instability of the molten metal surface, which has also the bad influence on the slab quality. Therefore, it is very important to choose the optimal position of the inductor coil and the optimal level of electric power to minimize the surface defects. In the present work, as a first step toward the optimization problem of the process, numerical studies are performed to investigate the effects of coil position and the electric power level on the meniscus shape and the flow field. As numerical tools, the boundary integral equation method(BIEM) is used for the magnetic field analysis and the finite difference method (FDM) with orthogonal grid generation is used for the flow analysis.

• Steel and Composite Structures
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• v.37 no.1
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• pp.1-14
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• 2020

Composite beams with corrugated steel webs represent a new innovative system which has emerged in the past decade for medium span in the construction technology. The use of composite beams with corrugated steel webs results in a range of benefits, including flexible spaces and reduced foundation costs in the construction technology. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled or welded ones. In the current research, an optimal designed I-girder beam with corrugated web has been proposed to improve the structural performance of continuous composite girder under bending moment. The experimental program has been conducted for six simply supported composite beams with different loading conditions. The tested specimens are designed by using one of the stochastic techniques called hunting search algorithm. In the optimization process, besides the thickness of concrete slab and studs, corrugated web properties are considered as design variables. The design constraints are respectively implemented from Eurocode 3, BS-8110 and DIN 18-800 Teil-1. The last part of the study focuses on performing a numerical study on composite beams by utilizing finite element analysis and the bending behavior of steel girders with corrugated webs experimentally and numerically verified the results. A nonlinear analysis was carried out using the finite element software ANSYS on the composite beams which were modelled using the elements ten-node high order quadrilateral type.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.709-712
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• 2015

This paper will introduce the development case study about virtual-reality-based operation training system for steel making process. Steel making process consist iron making process to create liquid steel, pig iron, by reduction process, steel making process to make molten steel by refining, continuous casting process to make slab, and rolling process to make final product like coil, plate. This steel making process deals with liquid and solid products, so facilities of steel making process are very various and complicated. In addition, according to various customer requirements, the recycle of facilities and recipes changing have been fast. So the training for skilled operators is very important point. In this paper, we develop steel making training system based virtual reality for training skilled operator. This system consists of virtual machine, virtual HMI, and virtual control panel. And for fitting the characteristics of each process and increasing the education effectiveness, we develop dynamic methods like the method of dynamic education system configuration, initial facilities setup operation education system, and etc.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.39-46
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• 2006

This paper analyzes the continuous Galerkin method for the space-time discretization of wave equation. The method of space-time finite elements enables the simple solution than the usual finite element analysis with discretization in space only. We present a discretization technique in which finite element approximations are used in time and space simultaneously for a relatively large time period called a time slab. The weighted residual process is used to formulate a finite element method for a space-time domain. Instability is caused by a too large time step in successive time steps. A stability problem is described and some investigations for chosen types of rectangular space-time finite elements are carried out. Some numerical examples prove the efficiency of the described method under determined limitations.

• Nuclear Engineering and Technology
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• v.4 no.2
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• pp.116-131
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• 1972

A fast neutron time-of-flight spectrometer has been constructed with suitable choice of target thickness and proton bombarding energy in Li$^{7}$ (p, n) Be$^{7}$ nuclear reaction for a continuous keV spectrum of neutrons at 0 degree in 1-nsec pulse from a Van do Graaff and a time-pick-up fast neutron detector assembled with a 5 mm-thick 92% enriched B$^{10}$ slab and four heavily shielded 4＂$\times$3＂ NaI scintillation detectors. Energy resolution of this spectrometer is better than 0.3% at 50 keV and the signal-to-background ratio is also improved. Total cross section measurements of several separated single isotopes have been carried out with this spectrometer and analyzed by Rmaxtrix multi-level computer code. The spin values and resonance parameters of each individual resonances are given.