Experimental Research On Quantitative Detection Of Defect Of Concrete-Filled Steel Square Tubular (CFRT)Columns

Concrete-filled steel square tubular (CFRT) are becoming more and more widespread structural applications in actual engineering, because they have the advantages of better stability and carrying capacity, simple connections between columns and beams, convenient construction and regular shape.Especially concrete-filled steel square tubular (CFRT) can effectively improve the ductility and adapt to the required of modern engineering structures to large span, heavy load, high development and withstand the harsh conditions.Because its concrete is poured at canned case, the concrete-filled steel tube’s quality is usually not very good.There are flaws in the concrete sometime. But all of these merits are based on the concrete-filled steel tube working well. If there are flaws in concrete-filled steel tube, its working performance will be greatly reduced. So people pay more and more attention to its quality state.The mostly used non-damaged test method in concrete-filled steel tube is the method of ultrasonic wave, but its accuracy is not very well,especially the quantitative detection technology is not mature.The goal of this paper is that how to try to study the quantitative detection technology apply to concrete-filled steel square tubular (CFRT).The author has learned a lot of references about the designing, investigated the ultrasonic detecting technology apply on qualitative and quantitative detection of defect of concrete filled steel tube (CFST) arch rib segment,induced the construction and the position of the most common defects. Determine the ultrasonic wave propagation path, and defect quantitative estimation formula,when the concrete-filled steel square tubular (CFRT) existence corner voids, center hole defects, void.Production of two groups with different section sizes of concrete-filled steel square tubular short columns, there are six roots in each group,which provided with different forms defect and do the ultrasonic testing to concrete-filled steel square tubular short columns.Based on the test results of previously proposed quantitative estimation formula calculation, and compared draw defect estimation size with actual defect size to verify the feasibility of the quantitative calculation formula.The test results indicate that when there are corner voids, center of the circular and square defects and faults in the concrete-filled steel square tubular (CFRT),the quantitative evaluation results and the actual is almost accordant,so the quantitative calculation method are feasible;but when there are the void and centered rectangular defect in the concrete-filled steel square tubular (CFRT),it is difference between estimation results and actual results.So it is necessarily do further research for the two types of defects.