Structural health monitoring (SHM) is playing an increasingly important role in ensuring the safety of structures. A shift of SHM research away from traditional wired methods toward the use of wireless smart sensors (WSS) has been motivated by the attractive features of wireless smart sensor networks (WSSN). The progress achieved in Micro Electro-Mechanical System (MEMS) technologies and wireless data transmission, has extended the effectiveness and range of applicability of WSSNs. One of the most common sensors employed in SHM strategies is the accelerometer; however, most accelerometers in WSS nodes have inadequate resolution for measurement of the typical accelerations found in many SHM applications. In this study, a high-resolution and low-noise tri-axial digital MEMS accelerometer is incorporated in a next-generation WSS platform, the Xnode. In addition to meeting the acceleration sensing demands of large-scale civil infrastructure applications, this new WSS node provides powerful hardware and a robust software framework to enable edge computing that can deliver actionable information. Hardware and software integration challenges are presented, and the associate resolutions are discussed. The performance of the wireless accelerometer is demonstrated experimentally through comparison with high-sensitivity wired accelerometers. This new high-sensitivity wireless accelerometer will extend the use of WSSN to a broader class of SHM applications.

In this paper, the fatigue performance of six steel–concrete composite beam specimens was tested following subjection to chloride-induced corrosion and cyclic freeze–thaw conditions. The specimens included cast-in-place concrete slab composite beams with uniformly distributed studs and precast concrete slab composite beams with a cluster distribution of studs. According to the climatic characteristics of large temperature differences between day and night in alpine and high-altitude areas of Qinghai Province of China, together with the working conditions of bridges under deicing salt after snow, corrosion tests and freeze–thaw tests of composite beam specimens were performed prior to fatigue testing. The test results show that the freeze–thaw cycle causes obvious frost heave damage to the concrete, which affects its strength and stiffness. When the composite beam specimens were subjected to fatigue loads, tearing failure of the steel plates at the welds and interface failure at the studs were observed. Furthermore, with the influence of stress amplitude, fatigue life was found to be related to the initial crack defect within the specimen itself. Reduction in the initial stiffness of composite beams was found to be affected by the freeze–thaw cycle, stud arrangement type (uniformly distributed or cluster distributed), and steel type (ordinary steel or weathering steel). However, the stiffness degradation rate of all specimens against loading times was essentially identical before fatigue failure.