AE monitoring of PC beam with partially grouted tendon subject to bending moment
In the case of a partially grouted cable of PC structures, the cable is still re-anchored by the grout even after the fracture of cable. Thus after the fracture, when the PC beam with a re-anchored cable is subject to loading, the grout, which is locally fractured due to the fracture of cable, may emit some elastic waves due to the friction of grout and cable. This assumption also opens up the possibility that if small elastic waves induced by the friction, i.e. AE (Acoustic Emission), is detected around the re-anchored area, this elastic wave may indicate the existence of cables fracture. Therefore, the purpose of this research is to evaluate the characteristic of AE detected around the re-anchored area of PC beam subject to bending moment. In the experiment, AE monitoring was carried out on two types of PC beams with the fractured and re-anchored stranded cable during loading and unloading of bending moment. In the experiment two types of PRC (Pre-stressed Reinforced Concrete) beams with the fractured stranded-cable were prepared: in Type A beam the interface between grout and void is located in the shear span, while in Type B beam the interface is located in the bending span. In fabrication of the specimens, the grout was injected into the sheath right after the introduction of prestress, and also the cable was cut one week after the introduction of pre-stress. Herein 10 AE sensors of 60 kHz resonance type are allocated two-dimensionally on one side of the beam to detect the elastic waves propagating in the beam during the test. During the bending test, most AE activities were detected around the maximum load and those AEs might be so-called a primary AE associated with the development of cracks due to bending moment. Thus to segregate a primary AE from a secondary AE associated with the shear friction of the material, the source locations of AE identified below 80% of the maximum load in the all steps are focused on. Then it is clearly found that in Type A specimen most of the AE sources are indentified around the grout fracture area, and that the AE source location is almost identical throughout the loading steps. Furthermore, when we focus on the peak frequency of AE signals, the sources of AE signals having lower frequencies in Type A are located mainly around the grout fracture area. This fact may indicate that these AEs might be a secondary AE caused by the friction between the stranded cables and grout. Finally, it can be said that if secondary AE signals is detected along with cables when the bean subject to loading, the detected AE may indicate the fracture of tendons.
Yoshinobu Oshima Tomoki Shiotani Motoyoshi Goto Toyoaki Miyagawa
Kyoto University, Kyoto 615-8540, Japan
国际会议
World Conference on Acoustic Emission(2011年声发射国际会议)
北京
英文
434-440
2011-08-24（万方平台首次上网日期，不代表论文的发表时间）