Experimental and Numerical Simulation of a Multilevel Structure Behaviour Subjected to Transient Loads

Abstract

The paper presents a low-cost experimental setup consisting of a shaking table, a displacement measuring system based on non-contact optical infrared (IR) sensors, along with a standard acceleration measuring system, based on PZT accelerometers and signal conditioners. A 3-level reduced scale model of a lightweight frame structure, subjected at the base by transient seismic loads, is presented in this study. A methodology to obtain good agreement between measurements and 3D finite element method (FEM) computations of a structure subjected to transient loads is presented. It consists in 3 steps. In the first and by applying sinusoidal loads at the base of the structure, a frequency domain study was done. In the second step, inducing free vibrations, a time-domain analysis was made. By using FEM as an inverse method to match experimental results, the elastic and damping properties of the structure materials were determined. In the third step, the validation step, transient load measurements were carried out for both accelerations and displacements. As the excitations loads and the response of the structure are transient, a simple integration of measured accelerations to obtain displacements is not possible. The measured displacements with low-cost noncontact optical IR sensors showed an acceptable accuracy in the small range of interest. The experimental measurements were compared with FEM computation results, showing good agreement.