Output-only modal parameter identification of civil engineering structures

Abstract

The ambient vibration measurement is a kind of output data-only dynamic testing where the traffics and winds are used as agents responsible for natural or environmental excitation. Therefore an experimental modal analysis procedure for ambient vibration testing will need to base itself on output-only data. The modal analysis involving output-only measurements present a challenge that requires the use of special modal identification technique, which can deal with very small magnitude of ambient vibration contaminated by noise. Two complementary modal analysis methods are implemented. They are rather simple peak picking (PP) method in frequency domain and more advanced stochastic subspace identification (SSI) method in time domain. This paper presents the application of ambient vibration testing and experimental modal analysis on large civil engineering structures. A 15 storey reinforced concrete shear core building and a concrete filled steel tubular arch bridge have been chosen as two case studies. The results have shown that both techniques can identify the frequencies effectively. The stochastic subspace identification technique can detect frequencies that may possibly be missed by the peak picking method and gives a more reasonable mode shapes in most cases.

Feasibility of Output-Only Modal Identification Using Wireless Sensor Network: A Quantitative Field Experimental Study

“…The identified first vertical bending mode shape of Wuyuan Bridge has an antisymmetric waveform, which is similar to the second mode shape of a simply supported beam. This identified result is consistent with the theoretical solution of the mode shape of arch bridges [39] and also consistent with the experimental results at another arch bridge in China [40].…”

Experimental and analytical studies on dynamic characteristics of a large span cable-stayed bridge

“…The mathematical background for many of these methods is often very similar, differing only from implementation aspects (data reduction, type of equation solvers, sequence of matrix operations, etc.). The benchmark study has been carried out for evaluating the dynamic characteristics from ambient vibration data [21].…”

Full scale monitoring of the twin chimneys of the rovinari power plant

“…The wind force is unknown, but this kind of excitation can be considered very similar to a random process in the frequency range investigated. The identification of the non-dimensional damping can therefore be performed using an output-only approach: in the present study the random decrement technique (RDT) was adopted along with the Hilbert method, [15]. A fourth-order Butterworth pass-band digital filter with band-pass 0.2Hz< f band <0.5Hz was used.…”