1,721,028 research outputs found
Damage assessment in concrete dams: a Kalman Filter approach
No full textThe paper focuses on the estimate of stiffness parameters concerned with large dams. Experimental records taken during shaking tests and/or micro-seismic activity are assumed as input data and the Kalman filtering approach is applied in order to determine optimal values of unknown elastic constants. The subject is related to the issue of monitoring, since possible changes of elastic properties can be interpreted as “indicators” of ongoing deterioration processes. The method has been implemented with the aim of estimating pairs of parameters (bulk modules and shear modules). In this way it is possible to consider undesired effects due to isotropic and deviatoric stress components, in accordance to the theoretical framework upon which several damage models are based.
Numerical simulations show that the technique discussed in the paper is suitable to detect a decrease of mechanical properties if adequate tests are carried out at regular intervals
Advanced numerical methods to evaluate pavements response: comparison and parametric anallysis
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System Identification Applied to Dam Safety and Integrity
No full textThe problem of damage assessment in dam structures is addressed: the aim is to employ a system identification technique (Kalman Filter) and determine unknown elastic constants, whose values can be related to the current structural conditions and can be interpreted as ‘indicators’ of degradation phenomena.
Namely, the final objective is the estimate of pairs of parameters (bulk modulus and shear modulus) in critical zones, where material properties might be affected by damage processes: the use of both moduli is justified by the fact that structural damage is often due to the combined action of isotropic and deviatoric stress components, as explained by various theoretical models.
After giving some basic information about the proposed method, we briefly discuss numerical simulations, which show that the Kalman Filter can be conveniently exploited to detect areas where damage has occurred and/or is spreading and/or is likely to be present
Multilayer elastic theory applied to stress-dependent materials for pavement response
No full textABSTRACT: The main objective of this study was to evaluate the performance of the Multi Layered Elasticity Theory (MLET) applied to pavement response in the presence of stress dependent materials. The resilient moduli of unbound layers are estimated by a generalized model with three parameters k1-k2-k3. The first part of the study deals with a homogeneous half space subjected a circular load with uniform pressure. In this phase an attempt has been made to evaluate only a single value of the (equivalent) modulus of elasticity that takes into account the stress state induced in the half space by a typical load and by the at-rest earth pressure. The second part of this study is centred on the analysis of the responses of traditional flexible pavements with the sub base layer characterized by non-linear behaviour. To this aim, an iterative method was used. Numerical results show that the response of sub base layers cannot be properly determined without taking into account the stress-dependent behaviour of the material
Boundary element algorithms for elastic-plastic analysis: an extension to describe damage effects
No full textORGANOMETALLIC AND COORDINATION CHEMISTRY ON PHOSPHAZENES .1. ZN(II), PD(II) AND PT(II) COMPLEXES ON SCHIFF BASE-CONTAINING CYCLOPHOSPHAZENES
No full textStructural dynamics: convergence properties in the presence of damage and applications to masonry structures
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