Acoustic Emission Analysis of Self-Consolidating Rubberized Concrete Beam-Column Connections under Cyclic Loading.

An experimental investigation has been conducted to monitor the cracking process in self-consolidating rubberized concrete (SCRC) beam-column connections with the aid of acoustic emission (AE). Reinforced concrete beam-column connections were cast using various SCRC mixtures containing six different crumb rubber (CR) percentages (0 to 25%) as a replacement of fine aggregates. The investigated connections were tested under reversed cyclic loading conditions and simultaneously monitored via three attached AE sensors per specimen. The AE data from each loading test were analyzed to detect the crack initiation and quantify the crack propagation in all specimens throughout the tests. This analysis involved studying the variations in the signal amplitudes, number of hits, and cumulative signal strength. In addition, b-value and intensity analyses on the signals’ amplitude and strength were completed to generate three additional AE parameters: b-value, historic index (H(t)), and severity (Sr). The influences of both CR content and sensor location on these AE parameters were highlighted. The results of the AE analysis performed herein allowed an early detection of the first cracks before they could be visually observed, regardless of CR percentage. The development of additional cracks due to further loading cycles was found to be associated with an overall increase in AE activities until failure of all tested specimens. Meanwhile, the increase in the CR content resulted in a noticeable reduction in the AE signal amplitudes. Finally, the results of intensity analysis parameters (H(t) and Sr) were used to develop a damage classification chart. This chart can successfully be used to identify the stages of first crack initiation and ultimate load in the SCRC beam-column connections. [ABSTRACT FROM AUTHOR]