Caractéristiques dynamiques des structures par la table vibrante de RISAM : Approche Expérimentale, Analytique et Numérique

Abstract

Over the last few decades, vibration tables have been widely used in the experimental field of structural dynamics, as the most appropriate tool for simulating a real seismic signal. However, the main challenge is to reproduce as faithfully as possible the dynamic behavior of structures subjected to seismic excitations. This fidelity is crucial to guarantee accurate and reliable results, and requires particular attention to the calibration of reduced models. In this context, experimental applications using RISAM's vibration table, based on the detection of the vibration signature of a reduced model, are carried out. A steel gantry with three degrees of freedom (3DOF) represents the reduced model. These applications involve a technique for identifying characteristics such as the natural frequency and acceleration measurements of the reduced model. These characteristics are essential for analyzing the dynamic response. The reduced gantry model was used to study its natural frequency characteristics by applying a random signal (white noise). The gantry was then subjected to harmonic dynamic excitation, with an accelerometer attached to measure its dynamic response. In addition to these experimental applications, two other approaches were adopted. An analytical methodology, based on DDS decoupled equations, and a numerical modeling using the SAP2000 finite element code. These steps provide an in-depth understanding of the dynamic behavior of the reduced model and enable us to verify the accuracy of the results obtained. A parametric study inspired by the principle of tuned mass dampers (TMD) was carried out. Analytical calculations, experimental measurements through the vibration table and numerical analyses using SAP2000 were carried out, adopting five portal frame cases with different mass arrangements. The results of this study demonstrate the effectiveness of the experimental approach using the vibration table for identifying dynamic characteristics and measuring the dynamic response of structures.