Search results for " buckling"
showing 10 items of 26 documents
Preoperative, Intraoperative and Postoperative Corticosteroid Use as an Adjunctive Treatment for Rhegmatogenous Retinal Detachment
2020
The treatment for rhegmatogenous retinal detachment (RRD) is surgery, including pars plana vitrectomy (PPV) and scleral buckling (SB). Despite surgical advances, degeneration of the photoreceptors and post-operative complications, such as proliferative vitreoretinopathy (PVR), often occurs as the result of inflammation, preventing complete visual recovery or causing RRD recurrence. There is increasing evidence that in the presence of RRD, the activation of inflammatory processes occurs and the surgery itself induces an inflammatory response. This comprehensive review focuses on the use of different formulations of corticosteroids (CCS), as an adjunctive treatment to surgery, either PPV or S…
Retinopathy of prematurity-current diagnosis and management
1993
Despite advances in ophthalmological care of premature infants, retinopathy of prematurity (ROP) remains a still unsolved problem for paediatricians as well as ophthalmologists. A survey of the current literature concerning drug therapy and surgical management as related to the different stages of ROP is given. The classification system for ROP according to the International Committee is presented as well as our screening policy in relation to the literature. The effectiveness in preventing severe cases of ROP and the toxicity of vitamin E supplementation in high-risk premature infants is still disputed and no recommendations can be given. Cryotherapy is recommended in symmetric cases of st…
Steady states and nonlinear buckling of cable-suspended beam systems
2018
This paper deals with the equilibria of an elastically-coupled cable-suspended beam system, where the beam is assumed to be extensible and subject to a compressive axial load. When no vertical load is applied, necessary and sufficient conditions in order to have nontrivial solutions are established, and their explicit closed-form expressions are found. In particular, the stationary solutions are shown to exhibit at most two non-vanishing Fourier modes and the critical values of the axial-load parameter which produce their pitchfork bifurcation (buckling) are established. Depending on two dimensionless parameters, the complete set of resonant modes is devised. As expected, breakdown of the p…
An extended Ritz formulation for buckling and post-buckling analysis of cracked multilayered plates
2018
Abstract An extended Ritz formulation for the analysis of buckling and post-buckling behaviour of cracked composite multilayered plates is presented. The formulation is based on: (i) the First-order Shear Deformation Theory to model the mechanics of the multilayered plate; (ii) the von Karman’s theory to account for geometric non-linearities ; (iii) the use of an extended set of approximating functions able to model the presence of an embedded or edge crack and to capture the crack opening fields as well as the global behaviour within a single cracked domain. The numerical results of the buckling analyses and the equilibrium paths in the post-buckling regime are compared with the results fr…
A single-domain Ritz approach for buckling and post-buckling analysis of cracked plates
2019
Abstract A Ritz approach for the analysis of buckling and post-buckling of plates with through-the-thickness cracks is presented. The plate behavior is described by the first order shear deformation theory and von Karman’s geometric nonlinearity. The admissible functions used in the displacements approximation are series of regular orthogonal polynomial supplemented with special functions able to decribe the dicontinuity across the crack and the singularity at the crack tips; boundary functions are used to fullfill the homogeneous essential boundary conditions. Convergence studies and analysis results are presented for buckling and post-buckling of plates with a central through-the-thicknes…
Architecture and kinematics of forearc basins and intra-caldera resurgences: new insight from the Paola Basin (western offshore Calabria region) and …
This thesis deals with the patterns of tectonic deformation at different time and spatial scales ranging from tens to millions of years and from one to tens of kilometers, respectively. The study areas are the Campi Flegrei (Campania region, Italy) and Paola Basin (western offshore Calabria region, Italy). The Campi Flegrei and its offshore prolongation, the Pozzuoli Bay, are a laboratory for investigating volcano-tectonic deformations at 1yr-1kyr timescale and 1km spatial scale related to the dynamics of the Neapolitan Yellow Tuff (NYT) caldera and its intra-caldera resurgence. Resurgence is the late stage, long-term uplift of a collapse caldera floor to form a dome-like structure. The com…
Multicriterion design of frames with constraints on buckling
2011
The present paper is devoted to the optimal design of frame structures subjected to static and dynamic loading assuming the material behaviour as elastic perfectly plastic. The relevant optimal design problem is formulated as a minimum volume search problem. The minimum volume structure is determined under suitable constraints on the design variables as well as accounting for different resistance limits: the elastic shakedown limit and the instantaneous collapse limit, considering for each limit condition suitably chosen amplified load combinations. The effects of the dynamic actions are studied on the grounds of the dynamic features of the structure taking into account the structural perio…
Flexural behavior of R.C. columns externally wrapped with FRP sheets
2012
In the present paper the compressive and flexural behavior of R.C. columns externally wrapped with FRP layers is examined. The investigation refers to a short compressed R.C. member having circular transverse cross-section and reinforced with longitudinal bars and transverse hoops or spirals. A first phase of the investigation was addressed to describing the constitutive laws of constituent materials (confined concrete core, steel bars in compression and in tension, FRP in tension). The second phase of the research was addressed to deriving the compressive and flexural responses in terms of load-axial shortening curves and momentaxial force interaction domain, to be compared with experiment…
COMPRESSIVE BEHAVIOR OF LAMINATED GLASS COLUMNS
2014
This paper examines the behavior in compression of glass columns having tee (T) transverse cross-sections. The work highlights the issues recurring in the design of glass columns in rapid diffusion in the transparent architecture such as: - flexural and torsional buckling; - long-term effects and effects related to the temperature; - glued connections between single panels. In the work expressions are given for the calculation of the loadcarrying capacity of columns. The cases of full connection and absence of connection between the panels are analyzed and discussed. The comparison between the analytical and the experimental results highlights that in the case of glass columns with T cross-…