**Abstract**

The main aim of this chapter is to monitor the cracking and damage assessment in steel-reinforced concrete (steel-RC) and glass fibre polymer-reinforced concrete (GFRP-RC) beams along with varying percentages of tension reinforcement ratio. Beam specimens measuring (150 230 2100) mm were tested using a four-point bending flexural test using a universal testing machine together with an AE monitoring system. Acoustic emission (AE) has been applied for the early monitoring of steel-RC and GFRP-RC structures using AE parameters such as cumulative AE hits, average frequency, rise angle, amplitude, duration and AE XY plots to evaluate the micro and macro cracking in the steel-RC and GFRP-RC beams specimens. The most popular applications of AE signal in structural health monitoring are specified on crack monitoring, quantifying the degree of damage, and crack classification. In this research, the results indicated that the average frequency and rise angle parameter of AE signal are applied to classify the types of cracks (flexural or shear cracks) that occur in steel-RC and GFRP-RC beams along with varying percentages of tension reinforcement ratio subjected to flexural loading. As a result of these findings, the AE approach may be used to examine crack monitoring and crack classification in steel and GFRP-RC beams with different percentages of tension reinforcement ratios.

**Keywords:** load-deflection, AE, crack classification, hits, GFRP bars, steel bars
