Monitoring and Analysis of Ancient Building Columns on the Basis of Relative Dynamic Method

Abstract

During the service period of ancient building structures, due to the cumulative development of local damage to load-bearing members such as columns, the structural strength and stiffness will decrease, which may lead to catastrophic accidents. The traditional damage recognition method based on modal parameters is sometimes not effective. In this study, the vibration analysis combined with the relative dynamic method is used to analyze the damage of the wooden columns of the ancient building. The dynamic damage identification experiment was performed on a single wooden column. The effects of compressing the wooden column, crack length, and application of axial pressure on the natural frequency of the wood column were explored. The natural frequency of the wood column was determined by data acquisition and signal processing (DASP) software, and the damage of the component was evaluated by analyzing the change in the natural frequency obtained under different states. Results of the relative dynamic method showed that the damages can be evaluated by observing the change in the natural frequency. However, determining the damage position and the damage form was impossible. Then the mode shapes at different frequencies were obtained by processing the time domain signal, Fast Fourier Transform (FFT) calculation, and simultaneously using the Eigensystem Realization Algorithm (ERA). It is able to detect the damage of the ancient building components without damage, adding experiments to verify it, and enriching the application of the relative dynamic method theory. According to the variation law of the vibration mode animation, the location of the crack is generally concluded.