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For the safety of cable-stayed bridges, it is very important to ensure the tensile forces of cables. The loss of cable force could significantly reduce load carrying capacity of the structure and even results in structural collapse. This study presents a smart PZT-interface associated with wireless sensing device for tendon force-loss monitoring in cable-stayed bridge. The following approaches are carried out to achieve the objective. Firstly, a smart PZT-interface is designed to monitor the cable force-loss by using electromechanical impedance-based method. Secondly, wireless impedance sensor node is designed for impedance monitoring. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Finally, a system of smart PZT-interface and wireless sensor node is evaluated for its performance on a lab-scale cable-anchorage model.

In this study, wireless structural health monitoring (SHM) system of cable-stayed bridge is developed using Imote2-platformed smart sensors. In order to achieve the objective, the following approaches are proposed. Firstly, vibrationand impedance-based SHM methods suitable for the pylon-cable-deck system in cable-stayed bridge are briefly described. Secondly, the multi-scale vibration-impedance sensor node on Imote2-platform is presented on the design of hardware components and embedded software for vibration-and impedance-based SHM. In this approach, a solarpowered energy harvesting is implemented for autonomous operation of the smart sensor node. Finally, the feasibility and practicality of the multi-scale sensor system is experimentally evaluated on a real cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.

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The main objective of this study is to examine the feasibility of using lead zirconate titanate (PZT)'s direct piezoelectric response as vibrational feature for damage monitoring in beam structures. For the purpose, modal strain energy (MSE)-based damage monitoring in beam structures using dynamic strain response based on the direct piezoelectric effect of PZT sensor is proposed in this paper. The following approaches are used to achieve the objective. First, the theoretical background of PZT's direct piezoelectric effect for dynamic strain response is presented. Next, the damage monitoring method that utilizes the change in MSE to locate of damage in beam structures is outlined. For validation, forced vibration tests are carried out on lab-scale cantilever beam. For several damage scenarios, dynamic responses are measured by three different sensor types (accelerometer, PZT sensor and electrical strain gage) and damage monitoring tasks are performed thereafter. The performance of PZT's direct piezoelectric response for MSE-based damage monitoring is evaluated by comparing the damage localization results from the three sensor types.