The Empirical mode decomposition (EMD) has significant advantages in nonlinear and nonsteady response signal processing algorithms, but in the actual application process, the EMD existed some defects, in which the modal aliasing and false mode phenomenon is most prominent, the modal aliasing phenomenon can be simple in the 1 intrinsic mode function (IMF) containing more than one order structure of intrinsic mode components. The false mode phenomenon is the frequency component that should not be existed, which has a serious influence on the identification accuracy of structural modal parameters. To solve this problem, this paper studies the above two defects in EMD, and proposes an improved EMD algorithm which combines the fast ICA algorithm (FastICA) in frequency band filtering and independent component analysis (ICA) algorithm. The structure frequency is identified by hilbert transform (HT), and the effectiveness of the proposed algorithm is verified by the the Benchmark structure.

The steel pipe was eroded easily in the acid alkali chemical environment and damp environment. In order to improve the durability and bearing capacity of the structure, the GFRP-concrete-PVC tube new type composite column was put forward on the basis of the research of steel tubular concrete column and GFRP tube concrete column. The GFRP-concrete-PVC tube column was designed to analyze the composite column axis pressure performance and the ANSYS for GFRP-concrete-PVC tube column was used to analyze the assembly axial compression column numerically.  The results showed that the bigger was the concrete strength, the bigger was ultimate bearing capacity of GFRP-concrete-PVC tube composite column, but the smaller was the increasing-rate of bearing capacity. With the increase of concrete strength, the constraints ferrule effect of GFRP outer tube to core concrete was reduced. The composite column constraint ability was the largest when concrete strength was C30, the ferrule constraint factor was 2.31.