• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.67-79
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• 2000

Critical loads and load-carrying capacities for steel scaffolds used as shoring systems were compared using computational and experimental methods in Part I of this paper. In that paper, a simple 2-D model was established for use in evaluating the structural behavior of scaffold-shoring systems. This 2-D model was derived using an incremental finite element analysis (FEA) of a typical complete scaffold-shoring system. Although the simplified model is only two-dimensional, it predicts the critical loads and failure modes of the complete system. The objective of this paper is to present a closed-form solution to the 2-D model. To simplify the analysis, a simpler model was first established to replace the 2-D model. Then, a closed-form solution for the critical loads and failure modes based on this simplified model were derived using a bifurcation (eigenvalue) approach to the elastic-buckling problem. In this closed-form equation, the critical loads are shown to be function of the number of stories, material properties, and section properties of the scaffolds. The critical loads and failure modes obtained from the analytical (closed-form) solution were compared with the results from the 2-D model. The comparisons show that the critical loads from the analytical solution (simplified model) closely match the results from the more complex model, and that the predicted failure modes are nearly identical.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.60-65
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• 2017

In this study, a simplified FE model for evaluating seismic performance of valve support was suggested and an apparatus for a real structure testing was developed. The seismic performances of three different types of valve supports were evaluated by the real structure testing. By comparing the results between the real structure testing and FEA using the simplified FE model, it was verified that the suggested simplified FE model can be utilized for comparative evaluation of seismic performance of valve supports.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.31-38
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• 2016

In this paper, the deformation-energy curves of the plastic hinges and the vessel bow, which are the major energy dissipation mechanism of a pile protective structures, were estimated, and the parametric study was performed by using those curves to apply the simplified collision model which developed in the previous study. Considered parameters were the mass of slab, the number of piles, the mass of vessel and the collision speed. As results, the difference of energy dissipation mechanism of two pile types (filled and non-filled) were revealed, and the collision behaviors of the protective structures could be tuned by the control of the inertia mass of capping slab. Therefore the simplified collision model can be used in a primary design and optimal design.

• Elastomers and Composites
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• v.46 no.1
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• pp.54-59
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• 2011

One of the viscoelastic flow behaviors during profile extrusion is the swelling of extrudate. In this study, die swell of rubber compound in the capillary die have been investigated through experiment and computer simulation. Simplified viscoelastic model and non-linear differential viscoelastic model such as PTT model have been used in the computer simulation. The simulation results have been compared with experimental data. Experiment and simulation have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells predicted by two models showed good agreement with experimental results. Pressure and velocity distribution, and circulation flow at the corner of reservoir have been well predicted by PTT model. Simplified viscoelastic model can not predict circulation flow at the corner of reservoir. However this model has an advantage in computation time compare with full viscoelastic model, PTT model.

• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.267-275
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• 2018

A numerical study of soil-foundation system under monotonic and cyclic pushover loading is conducted, taking into account both material and geometric nonlinearities. A complete and refined 3D finite element (FE) model, using contact condition and allowing separation between soil and foundation, is implemented and used in order to evaluate the nonlinear relationship between applied vertical forces and induced settlements. Based on the obtained curve, a simplified model is proposed, in which the soil inelasticity is satisfactorily represented by two vertical springs with trilinear behavior law, and the foundation uplifting is insured by gap elements. Results from modeling soil-foundation system supporting a bridge pier have shown that the simplified model is able to capture irreversible settlements induced by cyclic rocking, due to soil inelasticity and vertical loading, as well as large rotations due to foundation uplifting.

• Structural Engineering and Mechanics
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• v.13 no.5
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• pp.505-532
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• 2002

In this study, the analysis of high-speed vehicle-bridge interactions by a simplified 3-dimensional finite element model is performed. Since railroads are constructed mostly as double tracks, there exists eccentricity between the vehicle axle and the neutral axis of cross section of a railway bridge. Therefore, for the more efficient and accurate vehicle-bridge interaction analysis, the analysis model should include the eccentricity of axle loads and the effect of torsional forces acting on the bridge. The investigation into the influences of eccentricity of the vehicle axle loads and vehicle speed on vehicle-bridge interactions are carried out for two cases. In the first case, only one train moves on its track and in the other case, two trains move respectively on their tracks in the opposite direction. From the analysis results of an existing bridge, the efficiency and capability of the simplified 3-dimensional model for practical application can be also verified.

• 전기의세계
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• v.24 no.5
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• pp.67-71
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• 1975

A dynamic stability analysis of a large interconnected power system takes much time even though the modern large computer is used because of the high order of the system dynamic equations. By the necessity of the low order power system models, a simplified power system model of the generator with the high speed solid state exciter is developed in this paper. The usefulness of the reduced model is confirmed by comparing its eigenvalues and the transient responses with those of the original model in the single machine to infinite bus power system.

• IE interfaces
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• v.25 no.1
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• pp.106-113
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• 2012

There are few factors like a due date observance of the customer's order, reducing the manufacturing lead time, and minimizing the inventory investment to successfully run the manufacturing system. It is difficult for corporation and a person concerned to be offered indicators to achieve few factors mentioned above from complex manufacturing systems having much fluctuations. Simplified-DBR based on TOC(Theory of Constraints) is a management paradigm which can offer indicators to effectively face with fluctuating market's needs when market's demand is smaller than a capacity of manufacturing system. This paper is offering a core indicator and management model which is needed to successfully run the manufacturing system for corporation and a person concerned who have short experience and knowledge and newly construct Sinplified-DBR manufacturing system. Thus, this paper provides a systemic guidance in the offered model through the simulation.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.409-420
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• 2007

ASM No. 1 is a very useful model to analyze wastewater treatment system removing organic carbon and nitrogen material. But it isn't adequate to control the wastewater treatment system with real time since it has many material divisions and parameters. So, the purpose of this study is the simplification of ASM No. 1 to control the wastewater treatment system. ASM No. 1 was changed with the model which has 3 material divisions(COD, $NH_4{^+}$, $NO_3{^-}$) and two phases(Aerobic and Anoxic condition). SBR was running with two phases(Phase I and II). Phase II running 20 minutes with aerobic time was used for deciding model parameters and Phase I running 12 minutes with aerobic time was used for proving the simplified model. The simplified model was compared with ASM No. 1 using data of Phase I and II. As a result of model comparison, the simplified model has enough ability to express the variation of $NH_4{^+}$ compound.

• Earthquakes and Structures
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• v.18 no.4
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• pp.493-506
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• 2020

In this paper, a new opposition based charged system search (CSS) is proposed to be used as a parameter identification of highly nonlinear semi-active magneto-rheological damper. By replacing the opposition particles with current solutions, the mentioned strategy is used to enhance the search space and to increase the exploration of CSS. To investigate the effectiveness of the proposed method, a nonlinear modified Bouc-Wen model of MR damper is considered to find its parameters, and compare it with those achieved from experimental model of MR damper. Also, by exploiting the sensitivity analysis and using the importance vector, the less importance parameters in the Bouc-Wen model are eliminated which makes the MR damper model simpler. Results demonstrate the new proposed algorithm (OBLCSS) has a high ability to tackle highly nonlinear problems. Based on the results of the α importance vector, a simplified model is proposed and its parameters are identified by using the presented OBLCSS algorithm. The simplified proposed model also has a high capability of estimating damper responses.