Study Of Non-damaged Detection Method In Arch Bridge Of Concrete-Filled Steel Tube

The concrete-filled steel tube is a kind of steel-concrete complex material, its function is based on the steel tube and the concrete working together, which has merits of high strength,instead of bearer and form board. When it is used in arch bridge, it is more economic and convenience and it also settles the problems of the high anaphase loading of arch bridges. So it is widely used in engineering (specially in long-span arch bridge).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 is not as well as steel concrete when they are compared in the same state. The concrete-filled steel tube is usually used as arch rib when it is used in arch bridge, which also makes people pay more and more attention to its quality state .Above all of this, the concrete quality should be detected before it is used in practice.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. The goal of this paper is that how to improve the accuracy of ultrasonic wave method and try to study another non-damaged methods in concrete-filled steel tube. This article has thoroughly researched the method of ultrasonic wave and the method of impact echo. These researched works have been done as follows:1. The theoretical analysisThis method of non-damaged test has been deeply researched. To the traditional method of ultrasonic wave, the mechanical wave's dissemination rule has been researched deeply. The method of ultrasonic wave's main criterion is the time parameter .Taking the circular concrete-filled steel tube as the example, the effect to the time parameter caused by different concrete flaws has been discussed. To the method of impact echo, the feasibility of using it detecting the concrete-filled steel tube has been discussed. To the method of sound identify, the principle of research the sound signal in the tool of short wavelet has been discussed.2. The model assay and the practice assayIn the concrete-filled steel tube arch bridge model, the general concrete flaws in the concrete-filled steel tube have been installed (for example cavity,delamination and so on).Based on the arch bridge model, the assays of these non-damaged test method (the method of ultrasonic wave, the method of impact echo) have been done. Based on the analysis of test results, we try to find the regularity of concrete-filled steel tube's non-damaged test method. The impact echo assay are carried on the bridge of Maocaojie. The sound signals are recorded when knock the steel tube in difference place and are analysised in MATLAB toolbox. The new testing method are researched deeply, whose test criterion is based on phonics parameter (such as audio frequency or audio strength).3. The assay's analysisThrough the assay, it is discovered that the simple criterion cause the traditional method of ultrasonic wave's low accuracy. It can improve the detecting accuracy by using two or more parameters when detecting the concrete-filled steel tube. It can use the parameter of time and frequency to identify the honeycomb for the frequency parameter is sensitive to the flaw of honeycomb and non-sensitive to the flaw of delaminate. In the foundation of ultrasonic wave assay, the impact echo assay and the sound recognition assay are carried on. Through the research, it is discovered that using the method of impact echo detecting concrete-filled steel tube's thickness is feasible. The method of sound identify can detect the concrete-filled steel tube. Compared with the fine part's sound signal, the flaw part sound signal's amplitude and frequency is higher.Through the assay, it is found that the ultrasonic wave's accuracy can been improved by the way of using two or more parameters detect concrete flaws. The method of impact-echo can detect the concrete-filled steel tube's quality probably. The sound identify can detect the concrete-filled steel tube's flaws, finds out the place of flaws. Based on the assay, the ultrasonic wave's accuracy is improved, and the new non-damaged test method is researched in a little step.