System identification, model updating and simulation

During the Weimar Summer School course “Model Validation and Simulation” the project “System Identification, Model Updating and Simulation” has been performed. The project was about modal analysis of civil structures. As an example a down scaled “tower” was given. This tower was made of PVC water pipes, with a basement of concrete. Four acceleration sensors had been placed on the pipe by pipe clamps. So it was possible to measure the response of the structure for different excitations. Impulse forces were applied using a hammer from different directions. The force excitation in Newton and the resulting accelerations given by the sensors in m/s² have been recorded. For the measurements the sensors had been arranged in different setups with one sensor as reference, so it was possible to combine the setups later. The measured response was analyzed in order to identify the modal parameters including the natural frequencies, the mode shapes and the damping ratios of the structure using MACEC toolbox. Parallel to the real measurements a simulation has been prepared. The first step was to create two FEA models of the structure using the software packages ANSYS and SLang. The aim was to compare the results calculated by the different software. In the models were developed using beam elements considering the material properties of a PVC pipe. The models were used to calculate the modal parameters of the tower.