The shear resistance mechanisms of a reinforced concrete (RC) member with shear reinforcement can be divided into the contributions of concrete and shear reinforcement. The shear resistance mechanisms of concrete can be further divided into the shear resistance of intact concrete in the compression zone, the aggregate interlock in the cracked tension zone, and the dowel action of the longitudinal tension reinforcement. In this study, the shear demand curves and potential shear capacity curves for both tension and compression zones were derived with the assumption that the shear failures of RC members are dominated by the flexural-shear strength. On this basis, the shear capacity model was also proposed. In the proposed model, the crack width and the local stress increase in reinforcements were calculated based on the bond behavior between the reinforcement and its surrounding concrete, and the crack concentration factor was introduced to consider the formation and propagation of the critical shear crack developed from the flexural cracks. A total of 940 shear test results was collected and compared with the analysis results provided by the proposed model, and it was demonstrated that the proposed model provided a good estimation on the shear strengths of RC beams.

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Although wireless smart sensor platforms have been available over a decade, only a limited number of full-scale wireless smart sensor–based structural health monitoring implementations have been realized. Most wireless smart sensor platforms that are validated in full-scale implementations have now become obsolete and are no longer commercially available. While wireless sensing capabilities have grown, presenting significant opportunities, obstacles to wide application of wireless smart sensor for structural health monitoring exist both in terms of hardware and software. This article assesses the efficacy of the Xnode, a new wireless platform whose development has been driven by structural health monitoring requirements, as well as lessons learned from several full-scale wireless smart sensor deployments. The capabilities of the platform are evaluated in comparison with other commercial wireless smart sensors, in terms of hardware, software, and mechanical design. Extensive laboratory and field testing is employed to validate its performance on three aspects: fidelity of data acquisition, reliability of wireless communication, and efficiency of power management. Test results demonstrate the capabilities of the Xnode to support full-scale, high-fidelity data acquisition for civil infrastructure. In addition, the new sensor platform provides several significant benefits to extend the use of wireless smart sensors to a broader class of structural health monitoring applications, such as sudden event monitoring and real-time and control applications.

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