Prestress Monitoring of a Steel Strand in an Anchorage Connection Using Piezoceramic Transducers and Time Reversal Method

Abstract

Steel strands are widely used in cable stay or suspension bridges. The safety and stability of steel strands are important issues during their operation period. Steel strand is subjected to various types of prestress loss which loosens the wedge anchorage system, negatively impacting the stability of the structure and even leading to severe accidents. In this paper, the authors propose a time reversal (TR) method to monitor the looseness status of the wedge anchorage system by using stress wave based active sensing. As a commonly used piezoceramic material, Lead Zirconate Titanate (PZT) with a strong piezoelectric effect is employed. In the proposed active sensing approach, PZT patches are used as sensors and actuators to monitor the steel strand looseness status. One PZT patch is bonded to the steel strand, one PZT patch is bonded to the wedges, and another PZT patch is bonded to the barrel. There are three different interfaces of the wedge anchorage system to monitor the steel strand looseness status. In the first method, the PZT patch on the steel strand is used as an actuator to generate a stress wave and the PZT patch on the wedge is used as a sensor to detect the propagated waves through the wedge anchorage system. In the second method, the PZT patch on the steel strand is used as an actuator to generate a stress wave and the PZT patch on the barrel is used as a sensor to detect the propagated waves through the wedge anchorage system. In the third method, the PZT patch on the wedges is used as an actuator to generate a stress wave and the PZT patches on the barrel is used as a sensor to detect the propagated waves through the wedge anchorage system, of which the looseness will directly impact the stress wave propagation. The TR method is utilized to analyze the transmitted signal between PZT patches through the wedge anchorage system. Compared with the peak values of the TR focused signals, it can be found that the peak value increases as the wedge anchorage system tightness increases. Therefore, the peak value of the TR focused signal can be used to monitor the tightness of the steel strand. In addition, the experimental results demonstrated the time reversal method’s reliability, sensitivity and anti-noise property.

Study on Seismic Performance and Damage Analysis of Steel Plate Shear Wall with Partially Encased Composite (PEC) Columns

“…PZT (Lead Zirconate Titanate) is a type of piezoceramic material that possesses strong piezoelectric effect [49,50]. A PZT tranducer has the unique dual actuating and sensing functions along with its advantage of wide bandwidth, and therefore a PZT tranducer has the ability to generate and detect stress waves [51][52][53][54], including ultrasonic waves [55,56]. As the enanbling element for the active sensing method [57][58][59] and the electromechanial impedance (EMI) method [60,61], PZT transducers are often used in structural health monitoring (SHM) systems [62][63][64][65][66].…”

Tension Monitoring of Wedge Connection Using Piezoceramic Transducers and Wavelet Packet Analysis Method

“…A piezoelectric lead zirconate titanate (PZT)-based technique is often used in active monitoring the safety state of structures over their entire life cycle due to great features such as their broadband frequency response and the ability of being employed as actuators or sensors [25][26][27]. The recent research has shown that low cost PZT patches can be used for vibration detection [28,29], energy harvesting [30], stress wave generation [31,32], damage detection [33,34] and structural health monitoring [35][36][37][38].…”

Damage‐sensitive impedance sensor placement on multi‐strand anchorage based on local stress variation analysis

“…Due to the difficulty in installation of the optical fiber in the center wire, the application of FBG‐embedded strands has been extensively impeded in use. Zhang et al mounted three PZTs (lead zirconate titanates) on the surface of a lab‐scaled mono‐strand anchorage to monitor the prestress force using the reversal method. The feasibility of the method was evaluated with a maximum tensile stress of 20 MPa, which was quite less than the tensile strength of the prestressing strand.…”