In order to investigate the ultra-low cycle fatigue (UCLF) fracture in welded connections of high-strength steel (HSS) under earthquakes, this paper studies micromechanical fracture models for Q460C steel, which has wide application prospects in China. Notched round bars and smooth round bars, which were manufactured from base metal, heat-affected zone (HAZ), and weld metal of Q460C HSS, were tested under monotonic loading and cyclic loading, respectively. The fracture surface of tensile specimens were analyzed by scanning electron microscope (SEM) tests. This paper presents the results, including the skeleton curve, hysteresis loops, low cycle fatigue life, and characteristic length $l$ . By comparing the experimental results with the finite-element analyses, the toughness parameters of the void growth model (VGM), the stress-modified critical strain (SMCS) model, and the cyclic void growth model (CVGM) of Q460C HSS and its weld were calibrated. Results indicate that the toughness parameters of various materials for HSS are generally lower than that of normal strength steel. Also, in the welded beam-to-column connections, the HAZ requires more attention. The results can be used to effectively and accurately evaluate the UCLF fracture in welded HSS connections.

Human-building interaction is an emerging field of study that investigates the interactions and reciprocal impacts of humans and building systems. In this discipline, sensing technology is critical for data collection. The application of sensing technology is divided into six categories based on the research topics: (1) occupancy status, (2) occupant physiological indicators, (3) building components, (4) building environment, (5) building consumption, and (6) fusion of multi-sensing system. By evaluating 127 relevant research articles, this study attempts to provide a systematic review of the implementation of sensing technologies in each HBI research topic. Four significant sensing technologies were investigated for the occupancy status study: camera-based sensing, infrared-based sensing, radial frequency signal-based sensing, and ultrasonic sensor. Methodologies for biosensing brain activity, muscle and skin function, and cardiac function were examined as occupant physiological indicator measurements. The magnetic reed and vibration sensors were discussed for sensing changes in building components. The air property sensor, sound sensor, and illuminance sensor were introduced to monitor the building environment. The smart meter and smart plug were examined for sensing building consumption, and the application of multi-sensor fusion was also included in this article. Furthermore, this systematic study discussed three aspects of contemporary sensing technology deployment: data concealment, sensor cost tradeoffs, and privacy concerns.