Filtreler
The effect of concrete slab-rockfill interface behavior on the earthquake performance of a CFR dam

Bayraktar, Alemdar | Kartal, Murat Emre | Adanur, Suleyman

Article | 2011 | INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS46 ( 1 ) , pp.35 - 46

Earthquake response of the concrete slab is mostly depended upon its conjunction with rockfill This study aims to reveal the effect of concrete slab-rockfill interface behavior on the earthquake performance of a concrete-faced rockfill dam considering friction contact and welded contact Friction contact is provided by using interface elements with flue numbers of shear stiffness values 2D finite element model of Torul concrete-faced rockfill dam is used for this purpose Linear and materially non-linear time-history analyses considering dam-reservoir interaction are performed using ANSYS Reservoir water is modeled using fluid finite . . .elements by the Lagrangian approach The Drucker-Prager model is preferred for concrete slab and rockfill in non-linear analyses Horizontal component of 1992 Erzincan earthquake with peak ground acceleration of 0 515g is used in analyses The maximum and minimum displacements and principal stresses are shown by the height of the concrete slab and earthquake performance of the dam is investigated considering different joint conditions for empty and full reservoir cases In addition potential damage situations of concrete slab are evaluated (C) 2010 Elsevier Ltd All rights reserve Daha fazlası Daha az

Near-fault ground motion effects on the nonlinear response of dam-reservoir-foundation systems

Bayraktar A. | Altunişik A.C. | Sevim B. | Kartal M.E. | Türker T.

Article | 2008 | Structural Engineering and Mechanics28 ( 4 ) , pp.411 - 442

Ground motions in near source region of large crustal earthquakes are significantly affected by rupture directivity and tectonic fling. These effects are the strongest at longer periods and they can have a significant impact on Engineering Structures. In this paper, it is aimed to determine near-fault ground motion effects on the nonlinear response of dams including dam-reservoir-foundation interaction. Four different types of dam, which are gravity, arch, concrete faced rockfill and clay core rockfill dams, are selected to investigate the near-fault ground motion effects on dam responses. The behavior of reservoir is taken into acc . . .ount by using Lagrangian approach. Strong ground motion records of Duzce (1999), Northridge (1994) and Erzincan (1992) earthquakes are selected for the analyses. Displacements, maximum and minimum principal stresses are determined by using the finite element method. The displacements and principal stresses obtained from the four different dam types subjected to these near-fault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts on the dam types Daha fazlası Daha az

Examination of 3d long-term viscoplastic behaviour of a CFR dam using special material models

Karalar M. | Çavuşli M.

Article | 2019 | Geomechanics and Engineering17 ( 2 ) , pp.119 - 131

Time dependent creep settlements are one of the most important causes of material deteriorations for the huge water structures such as concrete faced rockfill dams (CFRDs). For this reason, performing creep analyses of CFRDs is vital important for monitoring and evaluating of the future and safety of such dams. In this study, it is observed how changes viscoplastic behaviour of a CFR dam depending the time. Ilısu dam that is the longest concrete faced rockfill dam (1775 m) in the world is selected for the three dimensional (3D) analyses. 3D finite difference model of Ilısu dam is modelled using FLAC3D software based on the finite di . . .fference method. Two different special creep material models are considered in the numerical analyses. Wipp-creep viscoplastic material model and burger-creep viscoplastic material model were rarely used for the creep analyses of CFRDs in the last are taken into account for the concrete slab and rockfill materials-foundation, respectively. Moreover, interface elements are defined between the concrete slab-rockfill materials and rockfill materials-foundation to provide interaction condition for 3D model. Firstly, dam and foundation are collapsed under its self-weight and static behaviour of the dam is evaluated for the empty reservoir conditions. Then, reservoir water is modelled considering maximum water level of the dam and time-dependent creep analyses are performed for maximum reservoir condition. In this paper, maximum principal stresses, vertical-horizontal displacements and pore pressures that may occur on the dam body surface during 30 years (from 2017 to 2047) are evaluated in detail. According to numerical analyses, empty and maximum reservoir conditions of Ilısu dam are compared with each other in detail. 4 various nodal points are selected under the concrete slab to better seen viscoplastic behaviour changes of the dam and viscoplastic behaviour differences of these points during 30 years are graphically presented. It is clearly seen that horizontal-vertical displacements and principal stresses for maximum reservoir condition are more than the empty reservoir condition of the dam and significant pore pressures are observed during 30 years for maximum reservoir condition. In addition, horizontal-vertical displacements, principal stresses and pore pressures for 4 nodal points obviously increased until a certain time and changes decreased after this time. © 2019 Techno-Press, Ltd Daha fazlası Daha az

Comparison of near- and far-fault ground motion effect on the nonlinear response of dam-reservoir-foundation systems

Bayraktar A. | Altunişik A.C. | Sevim B. | Kartal M.E. | Türker T. | Bilici Y.

Article | 2009 | Nonlinear Dynamics58 ( 4 ) , pp.655 - 673

In this paper, it is aimed to compare the near- and far-fault ground motion effects on the nonlinear dynamic response of dams including dam-reservoir-foundation interaction. Two different types of dams, which are concrete arch and concrete faced rockfill dams, are selected to investigate the near- and far-fault ground motion effects on the dam responses. The behavior of reservoir water is taken into account using Lagrangian approach. The Drucker-Prager material model is employed in nonlinear analyses. Near and far-fault strong ground motion records, which have approximately identical peak ground accelerations, of Loma Prieta (1989) . . .earthquake are selected for the analyses. Displacements, maximum and minimum principal stresses are determined using the finite element method. The displacements and principal stresses obtained from the analyses of dams subjected to each fault effect are compared with each other. It is clearly seen that there is more seismic demand on displacements and stresses when the dam is subjected to near-fault ground motion. © 2009 Springer Science+Business Media B.V Daha fazlası Daha az

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