Vibration and Stress Analysis of Multistory Steel Structure

Abstract

Modal parameters of structures and machines is crucial to determine the dynamic behavior during operation stages. A necessary step is to determine the dynamic characteristics and optimize the structure at its design phase to prevent any catastrophic failure. So, the purpose of this study is to focus on the modal parameters of steel structures both numerically and with experimentation and to shed some light on the equivalent stresses developed in the structure through numerical methods. Not only the modal parameters have been determined, but also the validation of the results through experiment. This will allow for accurate analysis on high-rise steel structures numerically without doing costly experiments. The mode shapes and natural frequencies of the 4-story structure for both loaded and unloaded conditions have been found through simulation in ANSYS. The first 6 modes have been extracted as these have been seen to affect the structure the most during dynamic loading condition such as earthquakes. These modal parameters have been validated using experimental method using a model 2-story structure through harmonic analysis. And finally, Von Mises stress analysis has been performed to find the relative stresses developed in the 4-story unloaded structure during different mode shapes and natural frequencies. From the research, the simulation results have been validated using the experimental data. And from the different loading condition of the structure, the different mode shapes and natural frequencies have been found. As the loading is changing from floor to floor, so is the change in mode shapes and natural frequencies. The shapes and natural frequencies greatly vary from the unloaded structure. The novelty of the research is that the modal parameters due to different loading conditions and compared those with an unloaded structure.