Stress Level Measurement in Prestressed Steel Strands Using Acoustoelastic Effect

In-situ health monitoring of the tensioning components such as strands, tendons, bars, anchorage bolts, etc. used in civil engineering structures, namely bridges, dams, nuclear power plants, etc. is extremely important to ensure security of users and environment. This paper deals with a guided ultrasonic wave procedure for monitoring the stress levels in seven-wire steel strands (15.7 mm in diameter). For this purpose, simplified acoustoelastic formulations were derived from the acoustoelasticity theory and acoustoelastic measurements were performed. The results from acoustoelastic calibration tests and an anchorage block of seven-wire steel strands are presented and discussed. They show the potential and the suitability of the proposed guided wave method for evaluating the service stress levels in the prestressed seven-wire steel strands.