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Paul J Tackley - One of the best experts on this subject based on the ideXlab platform.
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self consistent generation of tectonic Plates in time dependent three dimensional mantle convection simulations 2 strain weakening and asthenosphere
Geochemistry Geophysics Geosystems, 2000Co-Authors: Paul J TackleyAbstract:[1] In a previous paper [Tackley, 2000b] it was shown that a combination of temperature-dependent viscosity and viscoplastic yielding is sufficient to give rudimentary Plate tectonic-like Behavior in three-dimensional models of mantle convection. Here the calculations are extended to include two complexities that have been suggested as being important in localizing deformation at Plate boundaries: strain weakening and the presence of a low-viscosity asthenosphere. Introducing an asthenosphere by reducing the viscosity by a factor of 10 where material reaches a solidus (1) dramatically improves Plate quality, even if the asthenosphere is restricted to regions around spreading centers, (2) gives good, smoothly evolving Platelike Behavior over a wide range of yield stress values spanning an order of magnitude, and (3) gives bimodal stable solutions over a range of yield stresses; either immobile-lid or Plate Behavior may be obtained, depending on initial condition. By contrast, introducing an asthenosphere by using depth-dependent viscosity has a much smaller effect on system Behavior. Increasing strain weakening (1) improves localization at spreading centers but leads to an increasingly complex network of spreading centers fragmenting the Plates, (2) weakens convergent zones and can make downwellings highly episodic, and (3) does not lead to pure transform boundaries in these calculations. Time-dependent “damage” evolution and instantaneous strain-rate weakening give very similar results. All cases that display Platelike Behavior have very long wavelength mantle heterogeneity, consistent with Earth's.
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self consistent generation of tectonic Plates in time dependent three dimensional mantle convection simulations
Geochemistry Geophysics Geosystems, 2000Co-Authors: Paul J TackleyAbstract:[1] Presented here are self-consistent, three-dimensional simulations of mantle convection, some of which display an approximation of Plate tectonic Behavior that is continuous in space and time. Plate Behavior arises through a reasonable material description of silicate deformation, with a simple yield stress being sufficient to give first-order Plate-like Behavior; however, the required yield strength or fault frictional coefficient is much less than experimentally determined values. Toroidal:poloidal ratios are within geologically observed limits. The sensitivity of the system to yield strength and the form of strength envelope is systematically investigated. Optimum Plate character is obtained in a narrow range of yield strength, below which diffuse boundaries, and above which episodic Behavior, and eventually a rigid lid, are observed. Models with mobile lids develop very long wavelength horizontal structure, the longest wavelength possible in the domain. Two-dimensional models display much greater time dependence than three-dimensional models.
Vincent Caccese - One of the best experts on this subject based on the ideXlab platform.
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postbuckling Behavior of steel Plate shear walls under cyclic loads
Journal of Structural Engineering-asce, 1993Co-Authors: Mohamed Elgaaly, Vincent CacceseAbstract:In current design practice the capacity of a steel‐Plate shear wall is limited to the elastic buckling strength of its Plate panels. This practice results not only in a conservative design, but also in an undesirable one where the columns yield and may buckle before the Plate reaches a fraction of its capacity. Plate buckling is not synonymous with failure and if the Plate is adequately supported along its boundaries, as in the case of the shear wall, the postbuckling strength can be several times the theoretical buckling strength. Furthermore, due to the unavoidable out‐of‐plane imperfections, no change in the Plate Behavior will be observed at the theoretically calculated buckling load. Although the post‐buckling Behavior of Plates under monotonic loads has been under investigation for more than half a century, this Behavior under cyclic loading has not been investigated until recently. One test was conducted at the University of Alberta and 10 tests were conducted at the University of Maine. In this pa...
Mohamed Elgaaly - One of the best experts on this subject based on the ideXlab platform.
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postbuckling Behavior of steel Plate shear walls under cyclic loads
Journal of Structural Engineering-asce, 1993Co-Authors: Mohamed Elgaaly, Vincent CacceseAbstract:In current design practice the capacity of a steel‐Plate shear wall is limited to the elastic buckling strength of its Plate panels. This practice results not only in a conservative design, but also in an undesirable one where the columns yield and may buckle before the Plate reaches a fraction of its capacity. Plate buckling is not synonymous with failure and if the Plate is adequately supported along its boundaries, as in the case of the shear wall, the postbuckling strength can be several times the theoretical buckling strength. Furthermore, due to the unavoidable out‐of‐plane imperfections, no change in the Plate Behavior will be observed at the theoretically calculated buckling load. Although the post‐buckling Behavior of Plates under monotonic loads has been under investigation for more than half a century, this Behavior under cyclic loading has not been investigated until recently. One test was conducted at the University of Alberta and 10 tests were conducted at the University of Maine. In this pa...
Samuel W Easterling - One of the best experts on this subject based on the ideXlab platform.
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Behavior and modeling of a bolt bearing on a single Plate
Journal of Structural Engineering-asce, 2003Co-Authors: Samuel W EasterlingAbstract:One of the fundamental components of the moment-rotation Behavior of a steel or composite partially restrained (PR) connection is the load-deformation Behavior associated with high-strength bolts bearing on steel Plates. For many PR connections, the writers believe that this bearing Behavior can be approximated by the Behavior of a single bolt lap Plate connection. One of the primary components of the lap Plate connection Behavior is the local load-deformation Behavior associated with a single bolt bearing on a single Plate. This paper presents an experimental and analytical study of the single bolt single Plate Behavior. The results of the paper include specific methods for predicting the initial stiffness, strength, and overall load-deformation Behavior of the single bolt single Plate connection.
Victor A Eremeyev - One of the best experts on this subject based on the ideXlab platform.
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on the effective stiffness of Plates made of hyperelastic materials with initial stresses
International Journal of Non-linear Mechanics, 2010Co-Authors: Holm Altenbach, Victor A EremeyevAbstract:Within the framework of the direct approach to the Plate theory we consider the infinitesimal deformations of a Plate made of hyperelastic materials taking into account the non-homogeneously distributed initial stresses. Here we consider the Plate as a material surface with 5 degrees of freedom (3 translations and 2 rotations). Starting from the equations of the non-linear elastic body and describing the small deformations superposed on the finite deformation we present the two-dimensional constitutive equations for a Plate. The influence of initial stresses in the bulk material on the Plate Behavior is considered.