A bridge modal identification algorithm based on ambient excitation

An online, real-time analysis of the bridge vibration mode is often required during a bridge construction and maintenance. So a modal analysis algorithm with no human excitation is in urgent need. By researching the mathematical sense of NExT (Natural Excitation Technique) algorithm and ARMA model (Auto-Regressive and Moving Average Model), a quick solution for NExT-ARMA model is proposed on the basis of conventional algorithms. Compared to the traditional ambient modal analysis, this algorithm not only reduces the complexity of traditional method, but also build a feedback loop to improve the accuracy. Build a simply supported beam model both in ANSYS and real experimental platform to verify the algorithm. It shows that each mode of the bridge structure can be identified under nature white noise excitation. The relative error of the first three natural frequencies is 1% or less.