Experimental Study On Ultrasonic Testing Of Concrete Filled Steel Tubes Based On Acoustic Parameters

The concrete filled steel tube(CFST)has many advantages,such as high strength,plastic deformation,good aseismatic performance,convenient construction,good fire resistance and excellent economic effect.The concrete-filled steel tube has been widely used in high rise buildings and super high rise buildings.In the construction,the internal structure of concrete filled steel tube is complex,the emphasis and difficulty is to guarantee the quality of the internal core concrete construction,so its quality inspection is particularly important.At present,ultrasonic inspection of steel pipes for concrete defects detection,ultrasonic method has been widely studied and used due to its own unique advantages.In the CECS21:2000 revised edition of the Technical Specification for Ultrasonic Inspection of Concrete Defects issued by China Engineering Construction Standardization Association,Concrete internal defect detection technology provides a number of theoretical methods and quality requirements,so that the internal defects of concrete-filled steel pipe inspection work standards,the standard guidance,but no specific operational measures and theoretical data,operability is not strong,can not accurately guide the actual project It is still in the research and verification stage for the detection of internal defects of concrete-filled steel tube,especially in the quantitative and qualitative detection of internal defects of concrete-filled steel tube and ultrasonic CT scanning imaging technology.In this paper,based on the”Technical Specification for Detecting Concrete Defects by Ultrasonic Method",combined with the characteristics of concrete-filled steel tubular members in construction projects and their defect types,the ultrasonic method for detecting concrete defects of concrete-filled steel tubes is analyzed.The influence factors of the concrete parameters of the concrete filled steel tube are analyzed through the theory and experiment.Through the ultrasonic testing and the ultrasonic CT scanning defect test,Ultrasonic parameters in various types of defects and the characteristics of typical ultrasonic waveforms,and verify the use of external acoustic tube concrete-filled steel tube for internal quality of the three-dimensional reconstruction of the feasibility of the situation.Theoretical research shows that the acoustic parameters such as ultrasonic wave velocity,sound time,amplitude,frequency and waveform will change due to the existence of steel pipe wall and internal ribbed plate.Different types of transducers have certain influence on the ultrasonic acoustic parameters.Through the analysis of the results of the two tests,the characteristics of the acoustic wave data and the acoustic flaws of the typical defects are obtained.When the concrete hollow void value exceeds 1.4mm,the data are no longer normal by ultrasonic method.Accurate and validated the applicability of the three-dimensional acoustic inversion imaging software,but the data acquisition instrument still needs to be improved.