Nicholas D. Oliveto

University at Buffalo, The State University of New York | SUNY Buffalo · Department of Civil, Structural and Environmental Engineering

A three-dimensional formulation for a mass sliding with friction on a concave spherical surface is presented and used to describe the behavior of friction pendulum systems under extreme tri-directional excitation. The proposed approach accounts for large deformations and includes a procedure for handling the characteristic stop-and-go, or stick-sli...

The development of a six-axis load head based on the Stewart platform concept is described in this paper. The intended application of the device is in quantifying terminal forces and moments in flexible conductors interconnecting equipment in electrical substations. Such quantification is important is assessing seismic demand both at the terminal c...

Seismic isolation is a widely adopted technology for the protection of building infrastructure from earthquakes. As one of the most effective seismic protection devices, curved surface slider (CSS) systems have been studied extensively in the last few decades and are nowadays widely used all over the world. However, due to their relatively recent a...

Using a set of full-scale free vibration measurements, two separate state of the art identification strategies are implemented for the time domain identification of the modal properties of the superstructure of a three-story base-isolated building. In a first approach, the superstructure is modeled as a fixed-base linear 3-DOF system subjected to t...

A formulation is presented for the 2D dynamic analysis and earthquake response simulation of base isolation systems. The approach is force-based and consists of casting the computation in each time increment as a convex optimization problem. Interaction between the two horizontal components of response is considered in an elegant and simple way thr...

The behavior of high damping rubber bearings is highly complex. The models that are currently available are generally limited to unidirectional motion and, in most cases, difficult to extend to general bidirectional loading. One of the major limitations is their inability to characterize the behavior of the bearings at different levels of shear def...

High voltage transformers are essential parts of the electrical distribution grid. Severe failure of entire grids can occur during earthquakes, when transformer bushings fail due to structural dynamic mismatch to the seismic demands. Proper consideration of the fundamental frequency of vibration, which depends on the flexibility of the cover plate...

High damping rubber bearings have been used in the seismic isolation of buildings worldwide for almost 30 years now. After a brief introduction to the process leading to their manufacturing, a description is given of the main tests required by current seismic codes for the design of such devices. An extensive review is then presented of the models...

The dynamic identification of a four story reinforced concrete building retrofitted by base isolation is performed on the basis of push and release tests performed on the building. The identification is performed in two stages. In the first one the superstructure is considered as rigid and the isolation system is identified by using a tri-linear mo...

This report describes the implementation of a three-field poromechanics formulation in the Multiphysics Object Oriented Simulation Environment (MOOSE). A three-field formulation is necessary when the acceleration of the pore fluid relative to the porous skeleton is significant, and the compressibility of the skeleton material and pore fluid is much...

Floating offshore wind turbines are recently being considered widely for adoption in the wind power industry, attracting interest of several researchers and calling for the development of appropriate computational models and techniques. In the present work, a nonlinear finite-element formulation is proposed and applied to the static and dynamic ana...

A nonlinear finite-element formulation for the static and dynamic behavior of flexible beams was developed by appropriately modifying and extending the three-dimensional (3D) finite-deformation beam model originally developed by Simo. By introducing energy dissipation in a physically consistent way through a linear viscoelastic constitutive equatio...

The paper presents a constrained optimization procedure (COP) for the dynamic analysis of hybrid base isolation systems under earthquake excitation. After a description of the hybrid system considered, the mechanical model used for its representation is introduced, along with the governing equations. Mid-point central difference time-discretization...

The 3D finite deformation beam model originally developed by Simo is appropriately modified to derive a finite element formulation for the static and dynamic analysis of flexible electrical conductors. In contrast to what is currently carried out in the literature, a linear viscoelastic constitutive equation and an additional mass proportional damp...

The work presents several dynamic analyses of an actual base isolation system previously identified by using a non-linear 1D model and full scale free vibration tests. After a short introduction to the building and the base isolation system considered, reference is made to previous studies where the model used was developed. The analytical model, o...

Hollow-core composite post insulators, used in high voltage electrical equipment, are important parts of the power substation systems. In many applications the composite insulators are considered as slender cantilever columns, fixed at one end and connecting to a conductor at the other end. During earthquakes the post insulators are damaged and som...

An approach is presented for dynamic analysis of tensegrity structures in the small displacement regime. Such analyses are characterized by cables switching between taut and slack states. The approach is based on casting the computation in each time increment as a complementarity problem. Numerical examples are presented to illustrate the approach....

A procedure for the dynamic identification of the physical parameters of coupled base isolation systems is developed in the time domain. The isolation systems considered include high damping rubber bearings (HDRB) and low friction sliding bearings (LFSB). A bi-linear hysteretic model is used alone or in parallel with a viscous damper to describe th...

The response function of a dynamic system with viscous and friction damping is derived in the time domain and in the frequency domain, under a prescribed initial displacement. The response function in the frequency domain appears as the summation of three terms, each associated to a particular physical parameter of the dynamical system. Each of the...