11 Sep 2024

Evaluation of the Bridge Supplement Set overhead cable system with uneven bank heights

Abstract: A numerical model was developed to analyze the effects of environmental conditions and construction layout on the structural capacity of the modernized Bridge Supplemental Set (BSS). Environmental variables included even and uneven bank heights, soil strength, river width, and river flow rate conditions. Construction variables included tower placement, tower guy line orientation, and catenary length. Loading conditions, the drag force of the bridge due to river current, were conservatively applied with the assumption of uniform flow rate across the entire river width to account for the wide range of operating environments in which the BSS may potentially be used. Analysis of system performance informed several BSS construction optimizations to maximize system capabilities over the wide range of conditions considered. Catenary length was found to have the greatest influence on system performance, indicating that a small increase in catenary length would greatly reduce the loading on the critical components of the BSS, thus increasing the capacity and safety of the system. A stand-alone computer program was developed to quickly provide BSS construction guidance for a large variety of operating conditions, as the number of charts and figures required to account for most scenarios numbers in the thousands.

6 Sep 2024

Snow Surface Roughness across Spatio-Temporal Scales

Abstract: The snow surface is at the interface between the atmosphere and Earth. The surface of the snowpack changes due to its interaction with precipitation, wind, humidity, short- and long-wave radiation, underlying terrain characteristics, and land cover. These connections create a dynamic snow surface that impacts the energy and mass balance of the snowpack, blowing snow potential, and other snowpack processes. Despite this, the snow surface is generally considered a constant parameter in many Earth system models. Data from the National Aeronautics and Space Administration (NASA) Cold Land Processes Experiment (CLPX) collected in 2002 and 2003 across northern Colorado were used to investigate the spatial and temporal variability of snow surface roughness. The random roughness (RR) and fractal dimension (D) metrics used in this investigation are well correlated. However, roughness is not correlated across scales, computed here from snow roughness boards at a millimeter resolution and airborne lidar at a meter resolution. Process scale differences were found based on land cover at each of the two measurement scales, as appraised through measurements in the forest and alpine.

6 Sep 2024

Use of Chirp Sub-Bottom Acoustics to Assess Integrity of Water-Control Structures: Inner Harbor Navigation Canal Lock, New Orleans

Abstract: The US Army Corps of Engineers (USACE)-maintained lock on the Inner Harbor Navigation Canal serves as a critical navigation link between Lake Pontchartrain to the north and the Mississippi River to the south. Extensive slumping has been observed on the earthen embankment on each side of the lock, suggesting that internal pathways for water to escape through the lock’s concrete walls or joints are present. Unfortunately, traditional methods often used to identify cracks in the concrete (e.g., sidescan sonar) or water-filled voids under or behind the structure (e.g., ground-penetrating radar) did not identify any structural issues at this site. Prior to dewatering and repair, the USACE New Orleans District requested that the US Army Engineer Research and Development Center conduct a sub-bottom survey at the lock in order to identify water-filled voids and better prepare for potential repairs during dewatering. A unique sled was constructed that allowed a small vessel to tow the sub-bottom profiler at an angle to direct more acoustic energy into the structure. Low frequency, chirp acoustic energy successfully penetrated the concrete walls and identified several water-filled voids on both sides of the lock. A later post-dewatering walk-through indicated that the chirp imaged voids spatially adjacent to cracks, and cracks were not found in any other locations. Additional work is needed to further develop this methodology in other USACE structures.

5 Sep 2024

From Research to Production: Lessons Learned and Best Practices

Abstract: This paper provides an overview of best practices to assist individuals and teams in transitioning software from a research product into a production environment. The information contained in this paper consists of best practices and lessons learned from an assignment consisting of transitioning a science-based research suite of programs into a more modern software format with appropriate preparations and considerations to be deployed in a production environment. The original software suite was written using both MATLAB and Python programming languages, and the new production version was written in the Python programming language.

5 Sep 2024

Extending CEMHYD3D to Simulate Hydration of Portland Cement Pastes with High Volumes of Silica Fume

Abstract: Silica fume (SF) influences the hydration rate of Portland cement in differ-ent ways depending on the physical and chemical properties of the SF. This study reports the impact of SiO2 content (%), loss on ignition (%), and Brunauer–Emmett–Teller (BET) specific surface area on the hydration re-action of SF-cement paste mixtures. This study used five types of SFs with varying SiO2 content, loss on ignition (%), and particle morphology. Five SFs were mixed with Class H oil well cement at each of two different re-placement levels (20% or 30% by mass), and the released heat of hydra-tion was measured using isothermal calorimetry. The results were used to improve the pozzolanic reaction simulation feature of the original Virtual Cement and Concrete Testing Laboratory software, which enabled the soft-ware to simulate a higher SF replacement ratio in a cement mixture with higher fidelity. Results showed that a silica fume’s SiO2 content (%), loss on ignition (%), and BET specific surface area significantly influence the heat release rate. The new simulation model agrees well with the measure-ments on all the pastes tested.

5 Sep 2024

Next-Generation Water Quality Monitoring during Dredging Operations: Knowns, Unknowns, and Path Forward

Abstract: Water quality monitoring data are routinely collected during dredging and placement operations to address various state and federal requirements, including water quality standards, with the intention of protecting ecosystem health. However, such efforts may be limited by the lack of a standardized national strategic focus and user-friendly streamlined interfaces to interpret the data. Inconsistencies in how and what data are collected and lack of consensus on scientifically backed biological-effects thresholds make it difficult to quantify potential dredging operations impacts (or lack thereof) both within individual projects over time and across multiple projects of differing characteristics. Summarized herein is an initial effort to define a scientifically backed path forward to improve the value of current and future water quality monitoring and management decisions based on water quality data collected. The provided turbidity data were generally below applicable state thresholds for two case studies but for a third case study did periodically exceed thresholds at depth. This includes providing rationale for strategic focus on the most relevant dredging operations and projects, based on three general site-specific data categorizations: (1) sediment type, (2) dredge type, and (3) ecosystem type.

4 Sep 2024

Comparison of Numerical Simulations of Heat-Induced Stress in Basalt

Abstract: Energy losses due to excessive noise and heat are primary liabilities in traditional mining processes. Some of the currently researched methods to improve these liabilities involve heating the rock to induce internal stress fractures that make it easier to extract or remove rock with traditional mining equipment. Physical experimentation has yielded useful data that have been applied to numerical simulations of the heating and fracturing of rock, and multiple such simulations have been developed in the commercial multiphysics simulator COMSOL. Since COMSOL is not widely available on DoD high-performance computers, the goal of this research is to develop methods of replicating simulations developed in COMSOL as simulations that run in Abaqus FEA, another commercial multiphysics simulator. In this work, a simulated basalt cylinder with a 25 mm radius and a 158 mm height is subjected to a surface heat flux approximating the effects of a laser beam applied to the top of the cylinder. Simulated stress distributions, displacements, and temperatures obtained from both simulators are compared. When comparable results were not obtained using both simulators, the differences in results were investigated using simplified versions of the simulation.

30 Aug 2024

Particle Size Characteristics of Energetic Materials Distributed from Low-Order Functioning Mortar Munitions

Abstract: Particles of explosive filler distributed from low-order (LO) munition functioning are susceptible to dissolution and potential mobilization into groundwater and surface water. We command-initiated three mortar munitions as LO in triplicate using a fuze simulator and recovered particles from an ice surface to constrain LO particle characteristics. Total explosive mass recovery (19–55%) and spatial distribution (0->20 m) varied significantly both between munitions and between replicate LOs of the same munition. The median particle size (0.27–3.99 mm) varied with total mass recovery. In general, LO particles coarsened, and total mass deposition rates decreased logarithmically, with increasing distance from the initiation point.

29 Aug 2024

Experimental Evaluation of Steel Beams with Mechanical Section Reduction Retrofitted with Fiber Polymers

Abstract: Steel elements working in a harsh environment can be exposed to corrosion that degrades their performance and threatens the integrity of the whole structure. Recent studies propose using carbon (CFRP) and basalt (BFRP) fiber–reinforced polymers to repair corroded steel cross sections; however, most of these studies have not explored many of the structural characteristics, including ductility. In this study, we conduct a series of full-scale experimental tests to investigate the impact of corrosion, represented as mechanical section reduction, on steel beams as well as the impact of repairing the beams using CFRP and BFRP in enhancing the beams’ structural performance. Mechanical section reduction, introduced to the flange and web elements, is used to establish a baseline dataset that captures the impact of repairs in the absence of corrosion. Four-point bending loading conditions are utilized for all tested beams. The results show that the reduction of the flange and web section lowers the beams’ yielding load by 10% and 8%, respectively, compared with a beam with a full cross section. Utilizing CFRP and BFRP patches can partially restore the corroded beams’ ductility; however, the BFRP is outperforming the CFRP in improving their ultimate strength by 10% and enhancing their ductility by 10%.

28 Aug 2024

Integrating NOAA’s National Water Model (NWM) into the Antecedent Precipitation Tool (APT) to Support Clean Water Act Decision-Making

Abstract: This study examines the effectiveness of the National Water Model (NWM) in assessing streamflow normalcy under the Clean Water Act, compared to the commonly used Antecedent Precipitation Tool (APT). The APT, used by the Environmental Protection Agency, US Army Corps of Engineers, and environmental consultants, evaluates waterbody conditions based on precipitation data. However, it was found to be less accurate in predicting streamflow normalcy compared to USGS gage data. The NWM, on the other hand, showed promising results in preliminary analyses, outperforming the APT when compared to USGS gage records. This research expands on these initial findings, evaluating the NWM’s performance across the contiguous United States (CONUS) at gage locations indexed to the NHDPlus Version 2.1 stream network. The results suggest that the NWM provides adequate performance for assessing streamflow normalcy where USGS gages are not present, with accuracy ranging from 40% to 60% in the western half of CONUS and 60% to 80% in the eastern half.