Use of numerical methods for identifying the number of wire breaks in prestressed concrete cylinder pipe by piezoelectric sensing technology

Abstract

With theincreasing demand for long-distance transfer of water, prestressed concrete cylinder pipe (PCCP)has become the main pipe type due toits advantages among the pressure pipes. Detection for wire breaks is essential to prevent burst caused by a build-up of broken wires. After research on previous detection techniques, an innovative method based on piezoelectric sensing technology was proposed in this study. Multi-physics field prestressed concrete cylinder pipe (PCCP)-piezoelectric lead zirconate titanate (PZT) coupling finite element models containing actuators and sensors were established accordingly and taken on the linearity measurement to validate the model feasibility. A varying number of wire breaks were simulated in PCCP specimens with a diameter of 4 m to investigate their sensitivity to low-frequency sinusoidal and pulse signals. The stress wave field diagrams compare the healthy specimens versus the specimens with wire breaks at various time points to determine why the output voltage signals on the sensors change. Two types of damage indices, relative percentage deviation based on energy (RPDE) and amplitude (RPDA), were adopted to estimate the status of the wire breaks. The computation results indicated a linear correlation between the excitation and output voltages. Both the sinusoidal and pulse voltage signals were sensitive to the wire breaks, and the output voltage amplitudes changed with different low frequencies and numbers of wire breaks. However, there were some differences between the changing trends. Diffraction and reflection caused by wire breaks in stress wave propagation were the immediate causes of the energy loss and the time delay of primary wave. Furthermore, some other wave dissemination phenomena occurred, such as penetration, scattering, and reflection. The results coincide with the approximate experimental study regarding debonding detection of a concrete-filled steel tube and prove that the proposed approach is effective in identifying wire breaks. The damage index RPDE is suitable for determining whether there are broken wires and RPDA is fit for identifying the number of wire breaks for the 4 m-diameter PCCP specimens.