Dynamic monitoring of a super high-rise structure based on GNSS-RTK technique combining CEEMDAN and wavelet threshold analysis

Abstract

To capture the dynamic characteristics of a super high-rise structure under construction (i.e. Tianjin 117 Tower), multi-constellation GNSS-RTK (global navigation satellite system – real time kinematic) sensors are employed to derive the displacement information of the structure. A combined approach (CEEMDAN–WT) of complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and wavelet threshold (WT) technique is put forward to weaken the influence of background noise of sensors. For the sake of testing the effect of noise reduction via employing CEEMDAN–WT, a nonlinear signal with additive noise is introduced. Subsequently, the natural frequencies and the corresponding damping ratios of the structure are extracted based on the fast Fourier transform (FFT) and random decrement technique. In addition, the finite element model (FEM) of the structure is built to forecast the natural frequencies via modal analysis. The results show that: (1) The dynamic displacement information of super high-rise structures can be effectively determined based on GNSS-RTK technique; (2) The presented CEEMDAN–WT approach outperforms the single CEEMDAN and WT approaches; (3) The result obtained via the field measurement coincides with the FEM.