Abstract
A four-point bending test is performed for concrete filled square steel tubular beams strengthened by CFRP in longitudinal and circumferential directions. The mechanical parameters and acoustic emission (AE) signals are acquired for investigating the failure process. Test results indicate that the failure process could be divided into four stages including elastic, elastic-plastic, descending and softening stages, and AE parameters and waveforms are found to characterize this process properly. In addition, damage sources of the specimen are localized and position concentration degree (PCD) of AE events is defined which can quantitatively reflect the distributing regularity of damage sources along the axial direction under different loading conditions. The research suggests that, acoustic emission sensing technique can be used as an effective tool for on-line monitoring of damage degree and failure process of concrete filled CFRP- steel tube under bending load.