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International audienceCylindrical shells of arbitrary wall thickness subjected to uniform radial tensile or compressive dead-load traction are investigated. The material of the shell is assumed to be homogeneous, isotropic, compressible and hyperelastic. The stability of the finitely deformed state and small, free, radial vibrations about this state are investigated using the theory of small deformations superposed on large elastic deformations. The governing equations are solved numerically using both the multiple shooting method and the finite element method. For the finite element method the commercial program ABAQUS is used. The loss of stability occurs when the motions cease to be periodic. The effects of several geometric and material properties on the stress and the deformation fields are investigated

Elastic layers bonded to rigid surfaces have widely been used in many engineering applications. It is commonly accepted that while the bonded surfaces slightly influence the shear behavior of the layer, they can cause drastic changes on its compressive and bending behavior. Most of the earlier studies on this subject have been based on assumed displacement fields with assumed stress distributions, which usually lead to ''average'' solutions. These assumptions have somehow hindered the comprehensive study of stress/displacement distributions over the entire layer. In addition, the effects of geometric and material properties on the layer behavior could not be investigated thoroughly. In this study, a new formulation based on a modified Galerkin method developed by Mengi [Mengi, Y., 1980. A new approach for developing dynamic theories for structural elements. Part 1: Application to thermoelastic plates. International Journal of Solids and Structures 16, 1155-1168] is presented for the analysis of bonded elastic layers under their three basic deformation modes; namely, uniform compression, pure bending and apparent shear. For each mode, reduced governing equations are derived for a layer of arbitrary shape. The applications of the formulation are then exemplified by solving the governing equations for an infinite-strip-shaped layer. Closed form expressions are obtained for displacement/stress distributions and effective compression, bending and apparent shear moduli. The effects of shape factor and PoissonÕs ratio on the layer behavior are also investigated.

Traditional Ottoman timber-frame houses ("hımış") form the major part of the cultural heritage structures in Turkey. There are many studies in the literature regarding the seismic performance of hımış houses, which claim that these structures have an inherent seismically resistant property. However, these studies lack a quantitative engineering approach and are based on observations made after contemporary earthquakes. This study presents the results of the seismic resistance evaluation of traditional Ottoman houses, made by means of reverse cyclic frame tests conducted on six yellow pine and two fir frames with and without infill (brick and adobe) or cladding (bagdadi and şamdolma). The experimental study, which was intended to differentiate the effects of infill materials, frame geometry, and timber type, has revealed that frames with bagdadi cladding and adobe infill resulted in the best and worst structural performances, respectively, while high ductility and good energy dissipation capacity characteristics were determined.

Key wordsFracture mechanisms (formation of central bursts), damage coupled elasto-plasticity, finite strain, finite elements. MSC (2000) 00-xx Dedicated to Professor Peter Haupt on the occasion of his 70th birthdayMaterializing Continuum Damage Mechanics (CDM), numerical modeling of discrete internal cracks, namely central bursts, in direct forward extrusion process is presented. Accordingly, in a thermodynamically consistent setting, a local Lemaitre variant damage model with quasi-unilateral evolution is coupled with hyperelastic-plasticity. The formulations are constructed in the principal axes where simultaneous local integration schemes are efficiently developed. To this end, the framework is implemented as ABAQUS/VUMAT subroutine to be used in an explicit FE solution scheme, and utilized in direct forward extrusion simulations for bearing steel, 100Cr6. Discontinuous cracks are obtained with the element deletion procedure, where the elements reaching the critical damage value are removed from the mesh. The periodicity of the cracks shows well accordance with the experimental facts. The investigations reveal that, application of the quasiunilateral conditions together with the crack closure parameter has an indispensable effect on the damage accumulation zones by determining their internal or superficial character.

Nonlinear response history analyses (NRHA) of a 3-story isolated reinforced concrete (RC) building are carried out under both uni- and bi-directional earthquake excitations of near-field records. NRHA are conducted for a wide range of yield strength (Q/W) of lead rubber bearings (LRB), and isolation period (T). Selected near-field records are used to investigate both the contribution of orthogonal components on maximum isolator displacements and accuracy of equivalent lateral force (ELF) procedure on estimation of maximum isolator displacements. Analyses results show that both the contribution of orthogonal components and accuracy of ELF procedure depend on the soil condition where isolation system is implemented.

a b s t r a c tAlthough it is noted in the literature that the presence of a central hole in an elastic layer bonded to rigid surfaces can cause significant drop in its compression modulus, not much attention is given for investigating thoroughly and in detail the influence of the hole on the layer behavior. This paper presents analytical solutions to the problem of the uniform compression of bonded hollow circular elastic layers, which includes solid circular layers as a special case as the radius of hollow section vanishes. The closed-form expressions derived in this study are advanced in the sense that three of the commonly used assumptions in the analysis of bonded elastic layers are eliminated: (i) the incompressibility assumption, (ii) the ''pressure" assumption and (iii) the assumption that plane sections remain plane after deformation. Through the use of the analytical solutions derived in the study, the compressive behavior of bonded circular discs is studied. Particular emphasis is given to the investigation of the effects of the existence of a central hole on the compression modulus, stress distributions and maximum stresses/strains in view of three key parameters: radius ratio of the hole, aspect ratio of the disc and Poisson's ratio of the disc material.