12 Feb 2026

Numerical Study of Submergence-Induced Forces on a Maintenance Bridge

Abstract: The US Army Engineer Research and Development Center–Coastal and Hydraulics Laboratory conducted a numerical study for a proposed maintenance bridge over the Trinity River in downtown Fort Worth, Texas, that will be submerged in flood conditions. The purpose of this study was to determine the hydrodynamic loads on the structure. The study found that, due to a combination of peak velocities and water depth, a return period of 500 yr generates the largest drag forces, while the higher depth and discharge of the standard project flood generate larger lift forces. Two flow structures were observed with shallow submergence: The first resulted in a jet parallel to the deck with a recirculation extending from railing to railing and the second resulted in a plunging jet over the deck with smaller but stronger recirculation. These patterns resulted in significantly different loads on the structure. The study analyzed the bridge’s deck slope to the flow as a possible variable affecting the loads. Observed changes related mostly to the flow pattern predicted for different flow configurations. Finally, it was observed that an open railing provides the best possible conditions in terms of loading; therefore, minimizing the frontal area of the railing is recommended.

28 Jan 2026

Lightweight Deflectometer (LWD) Evaluation of Low Volume Road Structural Deterioration Under Military Traffic Loads

Abstract: In a combat zone, military vehicles may not have the benefit of traveling on well-constructed pavements, necessitating the use of low volume roads (LVR) to transport personnel and cargo. Military vehicles can cause rapid structural damage to LVRs that are not designed to withstand increased traffic loads. Currently, rapid pavement infrastructure assessment techniques for military personnel are based on qualitative visual inspections which do not provide estimates for structural capacity of the pavement. The objective of this project was to determine whether the lightweight deflectometer (LWD) can be used as a structural evaluation tool for LVRs in contingency operations. This study explored the capability of LWD equipment in evaluating factors that influence flexible pavement structural capacity: load-induced deterioration, soil moisture, and asphalt temperature. Falling-weight-deflectometer (FWD) and LWD tests were performed to measure pavement structural condition. The LWD was shown to be applicable for LVRs experiencing military traffic. The LWD is portable, simple to use, and more suitable than the FWD for LVRs when high rut depths are permitted. LWD data trended similarly to FWD data and therefore can be recommended as an alternate to the FWD in assessing the structural condition of LVRs for contingency planning.

14 Oct 2025

Literature on the Load Distributions for Effects on Hydraulic Steel Structures: Notes on Existing Literature for Establishing LRFD Load Factors

Abstract: Previous to 1993 Hydraulic Steel Structures (HSS) were designed using Allowable Stress Design (ASD); modern design, has transitioned to Load and Resistance Factor Design (LRFD) method, which targets a probability of a limit state. To implement LRFD, an understanding of the probability distributions of the loads applied to the structure, the resistances of the components of the structure, and the approximate durations and overlapping of these loads must be determined. The loads applied to HSS are dissimilar to loads applied to buildings or roads, so existing distributions cannot be applied to this problem. Any attempts to implement LRFD without these distributions will result in designs that do not target the probability of reaching a limit state. The USACE has adapted LRFD load combinations and factors to encompass the different geometry, force and displacement conditions, and environments present in HSS. This work collects literature for load effects on HSS to determine either probabilistic distributions or what loads sufficiently unknown to necessitate new research. Because the loads the HSS are subject to are dissimilar to other designed structures, these load distributions cannot be taken from them directly. Loads considered are hydrodynamic, barge impacts, debris impacts, ice expansion, seismic, wind, and waves.