Title: Adaptation of Pseudo-Dynamic Testing to structures with Fluid-Viscous Dampers (in Spanish: Adaptación del Ensayo Pseudo-Dinámico a estructuras dotadas de disipadores Fluido-Viscosos)
Authors: ZAPICO BLANCO Beatriz
Publisher: University of Oviedo
Publication Year: 2011
JRC Publication N°: JRC64933
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC64933
Type: PhD Theses
Abstract: Seismic testing of large-size models is nowadays possible thanks to the pseudo-dynamic method, which resembles the quasi-static method as it also consists in the application of slowly varying forces to the test structure. The small testing velocity involved in the pseudo-dynamic test may change the behavior of the materials with respect to their behavior at real velocity, which is called strain rate effect. The strain rate effect during a pseudo-dynamic test is not relevant for the classical construction materials, such as steel or concrete. However, it can be very important for some new materials, such as rubber or silicon, mostly used in isolators or energy dissipative devices. Silicone fluid viscous dampers, as manufactured by Jarret S.A., are an example of these dissipative devices, and they will be the subject of this thesis. It is possible to extend the pseudo-dynamic method range of application to full scale models of structures equipped with dissipative devices by introducing a homologation technique developed by the European Laboratory for Structural Assessment (Ispra, Italy). This technique consists in an on-line linear modification of the restitutive measured forces. In the present thesis, two new procedures of homologation are proposed. The first one is an improved version of the linear homologation. It consists in a linear filter where the output is the homologated force and the inputs are the measured forces and displacements. The second procedure is based on neural networks, using the same input variables as the filter method but adding the test velocity rate. The process followed with both methods is very similar. First, the most appropriate structure of the algorithms was selected and calibrated. This is based on experimental data obtained by testing dynamically the dissipation devices with a displacement pattern, which was specifically designed for this purpose, at different frequencies and test velocities. Then, the capability of the obtained filter/net is tested using experimental data coming from different experiments. Namely, quasi-static seismic tests carried out on a structure containing the same dissipative devices. Additionally, the most appropriate frequency for the training tests was studied. Outcomes were successful. Both algorithms outperform the previous linear homologation, the net-based one being the most accurate and versatile. It was found that the first natural frequency of the unprotected structure is an adequate reference for the training tests.
JRC Institute:Institute for the Protection and Security of the Citizen

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