Graphical Interface Toolbox for Modal Analysis

Abstract

This paper introduces a new graphical user interface (GUI) based software toolbox for modal parameters (eigenfrequencies, damping ratios and mode shapes) identification. The toolbox is a MATLAB based software that implements several stateof- the-art techniques for modal analysis. Three frequency domain based techniques: the peak picking (PP) method, the frequency domain decomposition (FDD) method and the enhanced frequency domain decomposition (EFDD) method as well as two time domain based techniques: the Eigen realization algorithm (ERA) combined with the natural excitation technique (NExT) and stochastic subspace identification (SSI) method are adopted in the toolbox. Most of these techniques can be used for experimental (inputoutput data), operational (output-only data) and combined modal analysis of structures. The program inputs are raw measured data and if available, the excitation force. The toolbox offers extensive functionalities for the visualization and processing of the data, the determination and visualization of the structure’s modal parameters and comparison of the identified modal parameters. The program is compact, efficient and user friendly, making it very intuitive and easy to handle. This paper contains a detailed description of the various modal analysis capabilities of the toolbox, and runs through a sample application using the toolbox to extract modal parameters of a 3-story building model using experimental data.