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Una tecnica di regolarizzazione per la dinamica non lineare di strutture sospese: validazione agli elementi finiti
No full textSmoothed "slack cable" models for large amplitude oscillations of suspension bridges
No full textThis paper proposes a technique to study the dynamics of suspension bridges in those cases where the use of traditional models is not possible, i.e., when the deformed shape of the structure allows the simultaneous presence of taut and slack hangers. The typical unilateral behavior of these suspension elements, which are unable to transmit compressive forces, introduces a discontinuity in the stiffness that implies strong computational difficulties in the solution of the equations governing the motion; as a consequence, the response of the continuous or discrete models proposed may be evaluated only through step by step time integration. In this paper an alternative technique is proposed, which replaces the distribution of unilateral hangers with a smooth nonlinear regular system made equivalent to the effective one by means of an energy criterion. The proposed technique, referred to as "equivalent nonlinearization," allows description of the motion through partial differential equations that are nonlinear but regular and, therefore, can be solved through classical perturbation techniques. The paper also describes two models formulated on the basis of the previously mentioned technique and some classes of solutions corresponding to particular characteristics of the forcing action
Identification of the modal properties of a squat historic tower for the tuning of a FE model
No full textUnilateral behaviour of the suspending hangers in the wind induced response of large span bridges
No full textA "deformable section" model for the dynamics of suspension bridges. Part II: Nonlinear analysis and large amplitude oscillations
No full textHysteretic Dissipators in Aluminium and Steel: Optimal Design and Preliminary Characterization Tests
No full textIn this paper the optimal design of a dissipator made of aluminium and steel and principally
subjected to shear forces and the preliminary results of the characterization tests are described.
The device has been designed on the basis of an optimization procedure with the objective to
maximize the energy dissipated in the device. The response of a 3D frame equipped with the
device and subjected to 7 earthquakes compatible with the response spectrum of Eurocode 8 is
shown. The optimal response obtained from the characterization tests exhibits a good
dissipative behavior of the device, highlighted by a wide enough hysteresis cycle
Seismic risk assessment of Trani’s Cathedral bell tower in Apulia, Italy
Get PDFThe present paper deals with the evaluation of the seismic vulnerability of slender historical buildings; these structures, in fact, may manifest a high risk with respect to seismic actions as usually they have been designed to resist to gravitational loads only, and are characterized by a high flexibility. To evaluate this behavior, the bell tower of the Trani’s Cathedral is investigated. The tower is 57 m tall and is characterized by an unusual building typology, i.e., the walls are composed of a concrete core coupled with external masonry stones. The dynamic parameters and the mechanical properties of the tower have been evaluated on the basis of an extensive experimental campaign that made use of ambient vibration tests and ground penetrating radar tests. Such data have been utilized to calibrate a numerical model of the examined tower. A linear static analysis, a dynamic analysis and a nonlinear static analysis have been carried out on such model to evaluate the displacement capacity of the tower and the seismic risk assessment in accordance with the Italian guidelines
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