• Structural Engineering and Mechanics
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• v.8 no.6
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• pp.561-578
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• 1999

The response of a reinforced concrete structure to loading is both immediate and time-dependent. Under a sustained load, the deflections caused by creep and shrinkage may be several times their instantaneous values. The paper describes a general finite element procedure, based on the so-called layered model, to analyse reinforced concrete members, and shows in particular how the simple Step by Step Method may be incorporated into this procedure. By invoking the Modified Newton Raphson Method as a solution procedure, the accuracy of the finite element method is verified against independent test results, and then applied to a variety of problems in order to demonstrate its efficacy. The method forms a general method for analysing highly indeterminate concrete structures in the time domain.

• Structural Engineering and Mechanics
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• v.36 no.2
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• pp.207-223
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• 2010

The aim of this study concerns with the construction stage analysis of highway bridges constructed with balanced cantilever method using time dependent material properties. K$\ddot{o}$m$\ddot{u}$rhan Highway Bridge constructed with balanced cantilever method and located on the 51st km of Elazi$\check{g}$-Malatya, Turkey, highway over Firat River is selected as an application. Finite element models of the bridge are modelled using SAP2000 program. Geometric nonlinearity is taken into consideration in the analysis using P-Delta plus large displacement criterion. The time dependent material strength variations and geometric variations are included in the analysis. Elasticity modulus, creep and shrinkage are computed for different stages of the construction process. The structural behaviour of the bridge at different construction stages has been examined. Two different finite element analyses with and without construction stages are carried out and results are compared with each other. As analyses result, variation of internal forces such as bending moment, axial forces and shear forces for bridge deck and column are given with detail. It is seen that construction stage analysis has remarkable effect on the structural behaviour of the bridge.

• Computers and Concrete
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• v.12 no.2
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• pp.169-186
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• 2013

The aim of this paper is to determine the effect of soil-structure interaction and time dependent material properties on behavior of concrete box-girder highway bridges. Two different finite element analyses, one stage and construction stage, have been carried out on Komurhan Bridge between Elazi$\breve{g}$ and Malatya province of Turkey, over Fırat River. The one stage analysis assume that structure was built in a second and material properties of structure not change under different loads and site conditions during time. However, construction stage analysis considers that construction time and time dependent material properties. The main and side spans of bridge are 135 m and 76 m, respectively. The bridge had been constructed in 3 years between 1983 and 1986 by balanced cantilever construction method. The parameters of soil-structure interaction (SSI), time dependent material properties and construction method are taken into consideration in the construction stage analysis while SSI is single parameter taking into consideration in the one stage analysis. The 3D finite element model of bridge is created the commercial program of SAP2000. Time dependent material properties are elasticity modulus, creep and shrinkage for concrete and relaxation for steel. Soft, medium, and firm soils are selected for evaluating SSI in both analyses. The results of two different finite element analyses are compared with each other. It is seen that both construction stage and SSI have a remarkable effect on the structural behavior of the bridge.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.620-624
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• 2011

This paper propose a new delay-dependent stability criterion of neutral time-delay systems. By employing double-integral terms in augmented states and constructing a new Lyapunov-Krasovskii's functional, a delay-dependent stability criterion is established in terms of Linear Matrix Inequality. Through numerical examples, the validity and improvement results obtained by applying the proposed stability criterion will be shown.

• Steel and Composite Structures
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• v.38 no.4
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• pp.447-462
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• 2021

In this work, we consider a problem in the context of thermoelectric materials with memory-dependent derivative for a half space which is assumed to have variable thermal conductivity depending on the temperature. The Lamé's modulii of the half space material is taken as a function of the vertical distance from the surface of the medium. The surface is traction free and subjected to a time dependent thermal shock. The problem was solved by using the Laplace transform method together with the perturbation technique. The obtained results are discussed and compared with the solution when Lamé's modulii are constants. Numerical results are computed and represented graphically for the temperature, displacement and stress distributions. Affectability investigation is performed to explore the thermal impacts of a kernel function and a time-delay parameter that are characteristic of memory dependent derivative heat transfer in the behavior of tissue temperature. The correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters.

• KIEE International Transaction on Systems and Control
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• v.12D no.1
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• pp.39-42
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• 2002

This paper focuses on the asymptotic stability of a class of neutral linear systems with mixed time-varying delay arguments. Using the Lyapunov method, a delay-dependent stability criterion to guarantee the asymptotic stability for the systems is derived in terms of linear matrix inequalities (LMIs). The LMIs can be easily solved by various convex optimization algorithms. Two numerical examples are given to illustrate the proposed methods.

• MALSORI
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• no.53
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• pp.143-156
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• 2005

Speaker adaptation in eigenvoice space is a popular method for rapid speaker adaptation. To improve the performance of the method, the number of speaker dependent models should be increased and eigenvoices should be re-estimated. However, principal component analysis takes much time to find eigenvoices, especially in a continuous speech recognition system. This paper describes a method to reduce computation time to estimate eigenvoices only for supplementary speaker dependent models and to merge them with the used eigenvoices. Experiment results show that the computation time is reduced by 73.7% while the performance is almost the same in case that the number of speaker dependent models is the same as used ones.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.131-138
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• 2003

This paper presents an analytical prediction of the prestress losses of prestressed concrete bridges. In this study a numerical procedure and computer program is developed to analyze the behavior of prestressed concrete bridges considering the time-dependent properties of material. It accounts for the aging, creep and shrinkage of concrete and the stress relaxation of prestressed steel. The structural model uses two dimensional plane frame elements with three nodal degree of freedom and is analyzed based on the finite element method. Member cross section can consist of concrete, reinforcement and prestressing steel. Two different set of equations for the prediction of time-dependent material properties of concrete are presented, which are ACI, CEB-FIP. The proposed numerical method for the prestress losses of prestressed concrete bridges is verified by comparison with reliable experimental results.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.920-927
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• 2017

With ever-advancing computer technology, the Monte Carlo (MC) neutron transport calculation is expanding its application area to nuclear reactor transient analysis. Dynamic MC (DMC) neutron tracking for transient analysis requires efficient algorithms for delayed neutron generation, neutron population control, and initial condition modeling. In this paper, a new MC steady-state simulation method based on time-dependent MC neutron tracking is proposed for steady-state initial condition modeling; during this process, prompt neutron sources and delayed neutron precursors for the DMC transient simulation can easily be sampled. The DMC method, including the proposed time-dependent DMC steady-state simulation method, has been implemented in McCARD and applied for two-dimensional core kinetics problems in the time-dependent neutron transport benchmark C5G7-TD. The McCARD DMC calculation results show good agreement with results of a deterministic transport analysis code, nTRACER.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.3
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• pp.287-308
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• 2018

This paper deals with blow-up phenomena for an initial boundary value problem of a quasilinear parabolic equation with time-dependent coefficient in a bounded star-shaped region under nonlinear boundary flux. Using the auxiliary function method and differential inequality technique, we establish some conditions on time-dependent coefficient and nonlinear functions for which the solution u(x, t) exists globally or blows up at some finite time $t^*$. Moreover, some upper and lower bounds for $t^*$ are derived in higher dimensional spaces. Some examples are presented to illustrate applications of our results.