17 Dec 2024

Full-Scale Demonstration of the Modernized Bridge Supplemental Set

Abstract: The Overhead Cable System (OCS) serves as the main anchorage system of the Bridge Supplemental Set and is used to hold the Improved Ribbon Bridge (IRB) against river flow. Several improvements have been made to OCS components and employment procedures, theoretically allowing the OCS to operate safely within most environments. However, the modernized OCS had yet to be constructed over an actual river, making it necessary to conduct a full-scale capability demonstration. Range W2 of Camp Ripley was selected as the test site because the 200th Multi-Role Bridge Company agreed to support the demonstration during an ongoing training cycle. A site reconnaissance trip revealed environmental obstacles on each bank, which made the site a unique test for the modernized OCS. The OCS model, a software package developed to analyze the loading imposed by river drag force on the OCS, was used to design a unique layout that circumvents Camp Ripley’s environmental challenges. The OCS was successfully deployed over Camp Ripley’s wet gap flowing at a river speed of 3.5 ft/s, and the IRB supported vehicular traffic for 3 hr before safe disassembly. Several lessons were learned regarding system deployment, and data were collected to facilitate technical manual development.

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.

29 May 2024

Performance of Army Corps of Engineers Mat System Using Anchorless Connections: A Follow-on Study of Site Stabilization for the Improved Ribbon Bridge Bridge Supplemental Set

Abstract: The US Army Engineer Research and Development Center conducted testing of the Army Corps of Engineers mat system with improved anchorage and connection hardware. Low-profile screw anchors replaced the ground anchorage of the existing system to reduce wear to tracks and wheels of vehicles while trafficking the system. Anchorless connections allowed the system to be placed over soils where the use of screw anchorage would be obstructed or would cause hazards to trafficking vehicles. Test tracks were constructed to evaluate the matting system with new anchorage and connection hardware over three different soils of weak sand and clay. Channelized traffic was applied to the test tracks using a loaded common bridge transporter. Performance of the updated system was evaluated with respect to results from previous testing, indicating that the improved anchorage and connection hardware increased the versatility of the matting system without sacrificing system performance.

17 Jul 2023

Testing Expedient Ground Anchor Solutions for Guyed Towers in Remote Cold Regions: Considerations for Cold Remote Regions with Limited Tools

Abstract: Ground anchors connected to guy wires for tower structures in cold climates suffer from frost heaving, which causes loss of wire tension and subsequent structural instability. It is necessary to understand what ground anchors are available to resist this tendency yet are still capable of expedient installation in remote areas. To that end, three metal, traditional ground-anchor types (arrowhead, bullet, and penetrating auger) and one novel polyvinyl chloride (PVC) T-post anchor were evaluated in frozen gravels and frozen silts at a research facility in Fairbanks, Alaska. Criteria included installation capability, failure loading, and removal ability. Additionally, expedient installation techniques for use in field conditions were also demonstrated. All three traditional ground anchors failed to penetrate frozen gravels. The penetrating auger also failed to penetrate frozen silts, but the arrowhead and bullet anchors did penetrate frozen silts with difficulty. The PVC anchor is capable of being installed only in a predrilled pilot hole. Under flexural load, the arrowhead anchor cable failed at 3686.72 lb, and the bullet anchor cable failed at 1753.44 lb. The PVC slid out of its hole at a direct-pull force of 1978.24 lb and failed under flexural stress at 202.32 lb.