22 Apr 2021

Automated Construction of Expeditionary Structures (ACES): Energy Modeling

Abstract: The need to conduct complex operations over time results in U.S. forces remaining in deployed locations for long periods. In such cases, more sustainable facilities are required to better accommodate and protect forward deployed forces. Current efforts to develop safer, more sustainable operating facilities for contingency bases involve construction activities that redesign the types and characteristics of the structures constructed, reduce the resources required to build, and reduce resources needed to operate and maintain the completed facilities. The Automated Construction of Expeditionary Structures (ACES) project was undertaken to develop the capability to “print” custom-designed expeditionary structures on demand, in the field, using locally available materials with the minimum number of personnel. This work investigated large-scale automated “additive construction” (i.e., 3D printing with concrete) for construction applications. This document, which documents ACES energy and modeling, is one of four technical reports, each of which details a major area of the ACES research project, its research processes, and associated results, including: System Requirements, Construction, and Performance; Energy and Modeling; Materials and Testing; Architectural and Structural Analysis.

22 Apr 2021

Estimating Bridge Reliability by Using Bayesian Networks

Abstract: As part of an inspection, bridge inspectors assign condition ratings to the main components of a bridge’s structural system and identify any defects that they observe. Condition ratings are necessarily somewhat subjective, as they are influenced by the experience of the inspectors. In the current work, procedures were developed for making inferences on the reliability of reinforced concrete girders with defects at both the cross section and the girder level. The Bayesian network (BN) tools constructed in this work use simple structural mechanics to model the capacity of girders. By using expert elicitation, defects observed during inspection are correlated with underlying deterioration mechanisms. By linking these deterioration mechanisms with reductions in mechanical properties, inferences on the reliability of a bridge can be made based on visual observation of defects. With more development, this BN tool can be used to compare conditions of bridges relative to one another and aid in the prioritization of repairs. However, an extensive survey of bridges affected by deterioration mechanisms is needed to confidently establish valid relationships between deterioration severity and mechanical properties.

29 Jan 2021

Environmental Applications of 3D Printing Polymer Composites for Dredging Operations

Abstract: This Dredging Operations Environmental Research (DOER) technical note disseminates novel methods to monitor and reduce contaminant mobility and bioavailability in water, sediments, and soils. These method advancements are enabled by additive manufacturing (i.e., three-dimensional [3D] printing) to deploy and retrieve materials that adsorb contaminants that are traditionally applied as unbound powders. Examples of sorbents added as amendments for remediation of contaminated sediments include activated carbon, biochar, biopolymers, zeolite, and sand caps. Figure 1 provides examples of sorbent and photocatalytic particles successfully compounded and 3D printed using polylactic acid as a binder. Additional adsorptive materials may be applicable and photocatalytic materials (Friedmann et al. 2019) may be applied to degrade contaminants of concern into less hazardous forms. This technical note further describes opportunities for U.S. Army Corps of Engineers (USACE) project managers and the water and sediment resource management community to apply 3D printing of polymers containing adsorptive filler materials as a prototyping tool and as an on-site, on-demand manufacturing capability to remediate and monitor contaminants in the environment. This research was funded by DOER project 19-13, titled “3D Printed Design for Remediation and Monitoring of Dredged Material.”

29 Jan 2021

Long-Term Durability of Cold Weather Concrete: Phase II

Abstract: Recent laboratory results confirm that it is possible to protect concrete from freezing solely using chemical admixtures and indicate that the amount of admixture required may be significantly less than previously recommended. Researchers have also verified that admixture-based freeze protection can produce concrete that is durable to winter exposure for a minimum of 20 years, through petrographic examination of core specimens obtained from past field demonstrations. Freeze protection for concrete using chemical admixtures alone has been an area of active research for 3 decades; however, the most recent methodology recommends very high addition rates of accelerating and corrosion inhibiting admixtures, which result in significant challenges, including slump loss, rapid setting, and potentially excessive temperature rise. As part of a laboratory study, researchers systematically varied the dosage of freeze protection admixtures used in concrete cured in a 23 °F environment. Preliminary findings indicate that a 50% reduction in admixture dose maintained adequate freeze protection and resulted in compressive strengths exceeding those of room-temperature controls at 7 and 28 days. The combination of improved handling, reduced cost, and verified durability associated with the use of admixtures for freeze protection makes a compelling case for broader adoption of this technique in winter operations

29 Jan 2021

Demonstration of Acoustic Sensing Techniques for Fuel-Distribution System Condition Monitoring: Final Report on Project F07-AR07

Abstract: Leaks in fuel storage tanks and distribution piping systems have been identified as a mission-critical problem by the Department of Defense and the U.S. Army. Fuel system leaks are often hard to locate and virtually inaccessible for efficient repair because the piping is often installed under a concrete pad or tarmac. Leak repair could cost up to $2,000, and the cost of cleanup and remediation for fuel spills can exceed $50,000. In this project an acoustic remote sensing system was installed to monitor an Army heliport refueling system to determine whether it could detect and accurately locate fuel leaks using computer software technologies to distinguish acoustic leakage signatures from normal fuel system operational noise.

29 Jan 2021

Simulations of Shoreline Changes along the Delaware Coast

Abstract: This technical report presents two applications of the GenCade model to simulate long-term shoreline evolution along the Delaware Coast driven by waves, inlet sediment transport, and longshore sediment transport. The simulations also include coastal protection practices such as periodic beach fills, post-storm nourishment, and sand bypassing. Two site-specific GenCade models were developed: one is for the coasts adjacent to the Indian River Inlet (IRI) and another is for Fenwick Island. In the first model, the sediment exchanges among the shoals and bars of the inlet were simulated by the Inlet Reservoir Model (IRM) in the GenCade. An inlet sediment transfer factor (γ) was derived from the IRM to quantify the capability of inlet sediment bypassing, measured by a rate of longshore sediments transferred across an inlet from the updrift side to the downdrift side. The second model for the Fenwick Island coast was validated by simulating an 11-year-long shoreline evolution driven by longshore sediment transport and periodic beach fills. Validation of the two models was achieved through evaluating statistical errors of simulations. The effects of the sand bypassing operation across the IRI and the beach fills in Fenwick Island were examined by comparing simulation results with and without those protection practices. Results of the study will benefit planning and management of coastal sediments at the sites.

29 Jan 2021

Mississippi River Adaptive Hydraulics Model Development and Evaluation, Commerce to New Madrid, Missouri, Reach

Abstract: A numerical, two-dimensional hydrodynamic model of the Mississippi River, from Thebes, IL, to Tiptonville, TN (128 miles/206 km), was developed using the Adaptive Hydraulics model. The study objective assessed current patterns and flow distributions and their possible impacts on navigation due to Birds Point New Madrid Floodway (BPNMF) operations and the Len Small (LS) levee break. The model was calibrated to stage, discharge, and velocity data for the 2011, 2015–2016, and 2017 floods. The calibrated model was used to run four scenarios, with the BPNMF and the LS breach alternately active/open and inactive/closed. Effects from the LS breach being open are increased river velocities upstream of the breach, decreased velocities from the breach to Thompson Landing, no effects on velocity below the confluence, and cross-current velocities greater than 3.28 ft/s (1.0 m/s) within 1186.8 ft (60 m) of the bankline revetment. Effects from BPNMF operation are increased river velocities above the confluence, decreased velocities from the BPNMF upper inflow crevasse (Upper Fuseplug) to New Madrid, cross-current velocities greater than 1.5 ft/s (0.5 m/s) only near the right bank where flow re-enters the river from the BPNMF lower inflow/outflow crevasse Number 2 (Lower Fuseplug) and St. Johns Bayou.

29 Jan 2021

Optical and Acoustical Measurement of Ballistic Noise Signatures

Abstract: Supersonic projectiles in air generate acoustical signatures that are fundamentally related to the projectile’s shape, size, and velocity. These characteristics influence various mechanisms involved in the generation, propagation, decay, and coalescence of acoustic waves. To understand the relationships between projectile shape, size, velocity, and the physical mechanisms involved, an experimental effort captured the acoustic field produced by a range of supersonic projectiles using both conventional pressure sensors and a schlieren imaging system. The results of this ongoing project will elucidate those fundamental mechanisms, enabling more sophisticated tools for detection, classification, localization, and tracking. This paper details the experimental setup, data collection, and preliminary analysis of a series of ballistic projectiles, both idealized and currently in use by the U.S. Military.

29 Jan 2021

Hydrologic Impacts on Human Health: El Niño Southern Oscillation and Cholera

Abstract: A non-stationary climate imposes considerable challenges regarding potential public health concerns. The El Niño Southern Oscillation (ENSO) cycle, which occurs every 2 to 7 years, correlates positively with occurrences of the waterborne disease cholera. The warm sea surface temperatures and extreme weather associated with ENSO create optimal conditions for breeding the Vibrio cholerae pathogen and for human exposure to the pathogenic waters. This work explored the impacts of ENSO on cholera occurrence rates over the past 50 years by examining annual rates of suspected cholera cases per country in relation to ENSO Index values. This study provides a relationship indicating when hydrologic conditions are optimal for cholera growth, and presents a statistical approach to answer three questions: Are cholera outbreaks more likely to occur in an El Niño year? What other factors impact cholera outbreaks? How will the future climate impact cholera incidence rates as it relates to conditions found in ENSO? Cholera outbreaks from the 1960s to the present are examined focusing on regions of Central and South America, and southern Asia. By examining the predictive relationship between climate variability and cholera, we can draw conclusions about future vulnerability to cholera and other waterborne pathogenic diseases.

29 Jan 2021

Stormwater Management and Optimization Toolbox

Abstract: As stormwater regulations for hydrologic and water quality control become increasingly stringent, Department of Defense (DoD) facilities are faced with the daunting task of complying with multiple laws and regulations. This often requires facilities to plan, design, and implement structural best management practices (BMPs) to capture, filter, and/or infiltrate runoff—requirements that can be complicated, contradictory, and difficult to plan. This project demonstrated the Stormwater Management Optimization Toolbox (SMOT), a spreadsheet-based tool that effectively analyzes and plans for compliance to the Energy Independence and Security Act (EISA) of 2007 pre-hydrologic conditions through BMP implementation, resulting in potential cost savings by reducing BMP sizes while simultaneously achieving compliance with multiple objectives. SMOT identifies the most cost-effective modeling method based on an installation’s local conditions (soils, rainfall patterns, drainage network, and regulatory requirements). The work first demonstrated that the Model Selection Tool (MST) recommendation accurately results in the minimum BMP cost for 45 facilities of widely varying climatic and regional conditions, and then demonstrated SMOT at two facilities.