Research On The Application Of Defects Detection Of Mass And Complex Concrete-filled Steel Tube By Ultrasonic Method

With the constantly emerging of the tall and super-tall buildings, concrete-filledsteel tube is widely used because of its superior mechanical properties such as highstrength, light weight, good ductility, fatigue resistance, impact resistance and so on.Recently, it appeared a lot of mass and complex structure concrete-filled steel tube.But the quality assurance of concrete after pouring is an important and difficultproblem in construction. Therefore, it is particularly important that the defect of themass and complex concrete-filled steel tube should be detected after concrete pouring.At present, some scholars have conducted reaserches on defects detection of mass andcomplex concrete-filled steel tube by method of piezoelectric ceramic and achievedgood effects. But at this stage, this kind of method is difficult to be widely applied topractical engineering for the higher price of the testing material and its poorrepeatable utilization and some other reasons.Ultrasonic method is used to detect the defects of concrete, which costs little, hashigh detection sensitivity and its equipment is repeatable. So reaserches on defectsdetection of mass and complex concrete-filled steel tube by ultrasonic method wasconducted.Based on the basic principle and method of defects detection by ultrasonicmethod, put forward that using ultrasonic method to detect the defects of mass andcomplex concrete-filled steel tube, that is using plane detection method, embeddedsounding pipe method and mixing method to detect the mass and complexconcrete-filled steel tube and play their respective advantages when detecting. Putforward related theory which is avalible for the defects detection of mass and complexconcrete-filled steel tube by ultrasonic method. Found out two particular factorswhich were plate and the kind of transducer for the defects detection of mass andcomplex concrete-filled steel tube by ultrasonic method. The influence of the twofactors on acoustic parameters values were analyzed in theory. Defect style in themass and complex concrete-filled steel tube was forcasted and proposedcorresponding detection mode and judgment. Ultrasonic method and its relevanttheories for the defects detection of mass and complex concrete-filled steel tube wereverified.Theoretical analysis and engineering practices show that: when ultrasonic goes through the bonding surface which is strong, the existence of thin steel plate which isabout40mm has no obvious impacts on sound velocity measurement value.This isconsistent with the theoretical analysis. For thicker steel plate and the small range, weshould pay much attention to the existence of the steel plate which may improve thevelocity of sound. The existence of the steel plate will reduce amplitude measuredvalues, but the decrease degree is smaller than the calculated value. The existence ofthe steel plate can make the frequency decline and decline in5kHz~15kHz. Theexistence of the steel plate will make the first wave gently and make the back of thefirst wave of waveform distortion. The type of transducer has an effect on the soundvelocity value but smaller influence on amplitude, frequency and waveform. Thesound velocity measurements value of a pair of flat transducer or combination of aplane and a radial transducer is greater than a pair of radial transducer’s. Throughthe analysis of testing results of two engineering examples, it shows that ultrasonicmethod can determine the type and location of defects within mass and complexconcrete-filled steel tube and verifies that it is feasible to use the ultrasonic method todetect defects in mass and complex concrete-filled steel tube.