Defects Detection Research Of Concrete-filled Steel Tube Based On Spectrum Analysis Method

Concrete-filled steel tube structure has a high bearing capacity, good seismic performance and good economy etc. It is widely used in high-rise and higher-rise buildings, as well as the large span bridge engineering field. Steel core concrete columns casting quality is directly related to the bearing capacity and durability of the structure, so carrying out the concrete filled steel tube structure NDT research has important theoretical significance and engineering application value. This paper analyzes the present situation of concrete-filled steel tube structure detection technology research and explore a kind of method of stress wave detection technology based on spectral energy ratio. Based on explaining these working principles of spectral energy ratio, which is applied to the defect detection test for concrete filled steel tubular column model. Through the analysis of frequency spectrum characteristics of the audio frequency stress wave to determine quality of steel pipe concrete casting in this paper, and it can verify the feasibility of spectral energy ratio analysis method to detect defects of concrete-filled steel tube column. The main research contents and conclusions are as follows:(1)Refer to a prototype of a steel pipe concrete columns in high-rise building design, it made a concrete-filled steel tube column with defect that Square cross section column length is 400mm. The defects include the column the hole defects and the Steel tube wall to take off the sticky defects.(2)Using the stress wave detector made independently by our university, which is carried out column wall sticky defect detection test of concrete-filled steel tube.Based on the MATLAB platform for data processing, get the main frequency intensity factor, and the results showed that the larger the red value, namely the greater the main frequency intensity factor, the worse interface bonding degree about the area of steel tube wall and concrete, and the greater the void.(3)Based on the platform of MATLAB combined with Golden Software Voxler3, the concrete hollow defect characteristics of concrete-filled steel tube column are carried on the numerical analysis.Through the steps including that Fourier transform, the solving of the spectral ratio, the numerical interpolation, the drawing of 3D volume and so on, it gets the 3D scatter plot, the iso-surface plot and rendering, etc. and clearly embodies the medium distribution of the concrete. The experiment results show that the greater transparency, namely the lighter color of the area, the worse the dense of concrete, and the deeper the color (the greater red value)in those area, the dense of concrete as possible, even some areas appear the phenomenon of hole.