Structural health monitoring (SHM) is essential for modern large buildings and infrastructure. Radio frequency identification (RFID) widen a new paradigm for SHM in the Internet of Things (IOT) era. This paper introduces a low-cost intelligent RFID monitoring system for future IoT applications. Through adding a multi-parameter sensing strategy to the passive RFID tags that can be deployed on a large scale to form a sensor network, which expands the coverage of IOT in key positions health monitoring of buildings. In this work, a novel chipless RFID strain sensing tag is designed to characterize the magnitude and direction of metal surface strain, and a low-cost detection method suitable for large mechanical structures is proposed. The traditional strain antennas focus on identifying the strain characteristics without the function of encoding, and there are limitations such as the rigid measurement methods and the expensive measurement instruments. The tag designed in this paper integrates both strain sensing and encoding functions, and has the advantages of small size, high data capacity, and information reading is not easily affected by environmental noise. This paper proposes an economical and flexible tag spectrum extraction method, which realizes the intelligent collection and transmission of tag data by connecting lightweight vector network analyzer (VNA) with microcontroller. Combined with the IOT, this method can be well applied to the security assessment and damage detection of large infrastructure structures, which provides a new approach to modern building health monitoring applications from integrated tag design to intelligent detection and risk assessment schemes.

When sensors based on a single patch antenna are used to monitor crack width, the issues of incomplete strain transfer ratio, insufficient bonding strength, and randomness of crack propagation will inevitably compromise sensor sensitivity and make the calibration uncontrollable. To circumvent these difficulties, this study presents a novel crack-measuring sensor based on a rectangular patch antenna fed by a pair of microstrip lines, which form a parallel plate capacitor as a crack-sensing unit. The sensing mechanism was analyzed using the transmission-line model. Then two crack sensor prototypes were designed and the dimensions were optimized. A crack opening simulator was customized to test the sensors by using different width resolutions. The experiment results validated that the resonant frequency shifts are linearly proportional to the applied crack width; moreover, the crack sensor proved capable of detecting crack widths as small as one-hundredth of a millimeter in an object.

In this paper, cables are proposed to connect the inerter and main frame for translation-to-rotation conversion, i.e., the cable-bracing inerter system (CBIS), with a magnified mass and enhanced damping effect. This novel configuration has the benefits of deformation relaxation at the connecting joints, easy installation, and an adaptive layout for nonconsecutive-story deployment. Dynamic motion equations were established for a single degree-of-freedom (SDOF) model equipped with a CBIS. The influence of dimensionless parameters, such as inertance-mass ratio, stiffness ratio and additional damping ratio on vibration mitigation were studied in terms of displacement response and force output. A single objective and multiple objective optimal design method were developed for a CBIS-equipped structure based on a performance-oriented design framework. Finally, the mitigation effect was illustrated and verified by a numerical simulation in a time-domain. The results showed that a CBIS is an effective structural response mitigation device used to mitigate the response of structural systems under earthquake excitation. Using the proposed optimization method, CBIS parameters can be effectively designed to satisfy the target vibration control level.