Understanding the mechanical behavior of lunar regolith simulants is crucial for progressing engineering analysis in surface infrastructure design and testbed evaluation. This study provides a detailed geotechnical characterization of the Colorado School of Mines Lunar Highlands Type-Testbed simulants, including a new highland-type lunar simulant integrated into the Mines Lunar Surface Simulator testbed. It includes the determination of key geotechnical properties such as particle size distribution, density, compressibility, cohesion, friction angle, and particle shape, using standardized ASTM testing procedures. Key findings show that while particle size distribution similarities exist among the simulants and actual lunar regolith, there are significant differences in density-dependent mechanical behaviors such as shear strength, compressibility, and deformation responses. These results emphasize the complexity of simulant fidelity and its impact on testbed experiments when simulating mid-Technology Readiness Level environments. Additionally, we emphasize the importance of density-specific testing for evaluating both geotechnical properties and simulant performance. This work presents the first comprehensive publication of the full geotechnical profile of Colorado School of Mines highland simulants and highlights the importance of using multiple parameters beyond just particle size distribution to evaluate simulant fidelity. Future research will concentrate on characterizing testbed variability and assessing properties across different density states to improve the application of lunar simulants in engineering analysis and testbed experimentation.

The growing population and increasing demand for surface transportation have highlighted the importance of maintaining safe and reliable civil infrastructures for daily use. Among all civil infrastructures, bridges are one of the most important elements in the transportation system. As such, to prevent any failures caused by aging and environmental impacts, bridges require periodic inspections. This becomes even more critical due to climate change and its effect on bridges, especially in the coastal regions. Most of the inspections conducted incorporate the visual type of evaluation due to its simplicity. However, with the current developments in new technologies, there is a need for more advanced techniques of structural health monitoring (SHM) methods to be incorporated in the maintenance programs for more accurate and efficient surveys. In this paper, non-destructive testing (NDT) methods applicable to steel bridges are reviewed, with a focus on methods applicable to local damage detection. Moreover, the methodology, advantages and disadvantages, and up-to-date research on NDT methods are presented. Furthermore, the application of novel NDT techniques using innovative sensors, drones, and robots for the rapid and efficient assessment of damages on small and large scales is emphasized. This study is deemed necessary as it compiles in one place the available information regarding NDT methods for in-service steel bridges. Access to such information is critical for researchers who intend to work on new or improved NDT techniques.

Ultra-high performance concrete (UHPC) is a durable material that can be used in constructing new and unique structural elements. This research utilizes UHPC to construct prefabricated shells that act as stay-in-place forms for bridge columns and eliminate the use of traditional formwork. These innovative structural elements reduce the on-site construction time, improve the structural performance of the column, and act as a protective layer in aggressive environments. Generally, during the construction process, the prefabricated UHPC shell is placed around the column reinforcement, which is fabricated using conventional methods. To connect the UHPC shell and column reinforcement with the footing and footing dowels, a step made of UHPC is utilized. The UHPC step connection is designed to shift the plastic hinge away from the column-to-footing interface. In the next stage, normal concrete is cast inside the shell, forming a concrete-filled UHPC shell. The final stage of construction involves placing and connecting a prefabricated cap-beam using the same UHPC step connection. The column specimen was tested under constant axial load and incremental lateral load. In this test, the UHPC shell cracked on the north side at a drift ratio of 3%; however, the column had a significant capacity and behaved similarly to a conventional reinforced concrete column during higher cycles of drift ratios. The test was completed after the column had reached a drift ratio of 7.5% when the first bar ruptured. No damage occurred in the footing and UHPC step which proved that the design was successful in shifting the plastic hinge away from the column-to-footing interface.