Geotechnical and Structures Laboratory Tommy Bevins US Army Engineer Research and Development Center Vicksburg, Mississippi JLOTS Force Projection from the Sea 29 January 2004 Rapid Port Enhancement: TSV Causeway Superstructure Concepts

Geotechnical and Structures Laboratory Understand the Battlespace Environment Enable Theater Access Provide Assured Mobility Deny Enemy Freedom of Action Enable Force Protection and Security Engage and Control Populations Neutralize Hazards and Restore the Environment Objective Force Maneuver Support Imperatives

Geotechnical and Structures Laboratory Development Milestones Develop initial concepts (FY03) Develop tools for evaluation and testing (FY03) Downselect optimal concepts (FY04) Laboratory testing (FY04) Scaled field testing (FY05) “Final” design (FY06)

Geotechnical and Structures Laboratory Major Challenges Water 15 feet Tidal variation and effects an substructure support Point loads on hydrotube Storage and erection logistics Uneven, jagged, and and weak Subsurface Tube roll stability under off-center loads Load bearing limitations of hydrotube Stiffness/strength requirements of superstructure

Geotechnical and Structures Laboratory Cross-beam/Treadway Concept FRP Box Beams: Intermediately ~10 ft. o.c. Hydro-beam supports Stay-cables Continuous FRP U-beams: provide longitudinal stiffness and vehicle guides.

Geotechnical and Structures Laboratory Double-Tube Concept FRP Box Beams: articulated and roll-stored Ideally would bear directly on tube May require continuous longitudinal "stiffening girder" for bearing distribution

Geotechnical and Structures Laboratory Tube-Confined Backfill Dredged Sand Expedient Mat Restraining Cables to hold tubes together Restraining Cables Dredged Sand End Restraint (Technical Challenge!) Existing TSV Ramp Tube, each side Side View End View NOTE: Hydro-tube out of water causes no problems. Tube Retaining Structure Tube Retaining Structure

Geotechnical and Structures Laboratory Construction Time –2-4 Days (Tube only) Issues Attaching Superstructure Site Condition –Sufficient Fill Material Achieving Sufficient Height –H  (5/8)*D H decreases as quality of fill decreases. Stability –Stacking required to achieve height. Porous fabrics – loss of fill over time Damage is a given in open environment D H Geotextile Tubes

Geotechnical and Structures Laboratory Floating Concept Basic Stiffened Section Section Stiffening Options Strap Stiffened Section Concept: Woven strapping system forms lower chord of stiffened section. Floats are part of stiffening mechanism. Mechanically Stiffened Section Concept: Sections are mechanically stiffened at connections. Floats only provide floatation. Moment resisting connections Hinges

Geotechnical and Structures Laboratory Analysis Considerations Global Stability –Stiffened Section Length –Unit Length Floatation –Number and Size of Floats per Unit –Attaching to superstructure Beam Strength –Cross-Section –Material Hydrodynamics –Wave Loadings Unit Stiffened Section For Mechanically Stiffened Sections

Geotechnical and Structures Laboratory Analytical Approximations Model represents single track- line or wheel-line Use ½ of Live Load, Dead Load, and Flotation Support Ramp load is not included at this time. Shore support is not included at this time. 30% Overload

Geotechnical and Structures Laboratory Analytical Approximations (Continued) Springs Deck Structure Spring Stiffness Beams Constrained Node Pairs Deck Structure Joints Floats

Geotechnical and Structures Laboratory Analysis Results, 10 Ft, Preliminary Decking Submerged Pinned Only

Geotechnical and Structures Laboratory 150 ft. Causeway, 30 ft. Stiffened Sections Self-Weight Loading Stiffened Section Load Case 1 Ramp TSV Total Loading

Geotechnical and Structures Laboratory 150 Ft Causeway Section Length (Feet) Displacement (inches)UNK Moment (in-lb)3E66E6

Geotechnical and Structures Laboratory 70 Ton M1 Tank Shear and Moment Summary LengthLoadDisplacementForces Tot al (ft) Sectio n (ft) Unit (ft) Type Cas e Star t (ft) Stop (ft) Tota l (in) Beam (in) L/D Moment (in-lbs) Shear (lbs) Spring Compression (lbs) +-+-MaxMin T E56.1E63.8E4 1.2E42.1E R --3.0e61.4E62.7E42.4E42.0E40.0E R --3.2E62.3E63.6E42.5E41.7E41.2E R --4.2E65.0E63.6E42.8E41.3E43.0E T E63.3E63.3E4 1.4E41.5E E40.0E R --1.9E6 3.1E41.3E42.0E42.4E R --2.2E61.9E62.6E43.0E42.0E42.3E E41.4E3

Geotechnical and Structures Laboratory Shear and Moment Diagram, 30 ft. Section

Geotechnical and Structures Laboratory Comparison of Section Lengths Model 30 ft. Section 50 ft. Section 150 ft. Section Negligible Difference

Geotechnical and Structures Laboratory Gravity Load, 22.2 inch displacement 40 Ft Stiffened Sections: 86.5 inches 160 Ft Stiffened Section: 49.8 inches 8 Ft Diameter Floats

Geotechnical and Structures Laboratory Future Analytical Plans Wave loadings –Partially Complete Preliminary strength design for main girders –Update FE model values and check design Small scale experiments to verify analytical assumptions Update model to 3D for lateral stability analysis. –Add beam element models for main girders and floor beams. Detailed 3D structural modeling for design of causeway sections –Stringers –Skin plates For Mechanically Stiffened Sections

Geotechnical and Structures Laboratory

TSV Deployment Boat or shore winch Assemble on deck as hinged unstiffened units. Drag units off deck with deployment boat. Deploy Stiffening Trusses (if req'd) Draw units together and stiffen section (see details) TSV Ramp TSV TSV Anchorage Anchorage Req'd Folded or stacked units Unit Stiffened Section Deployment Concept TSV Ramp

Geotechnical and Structures Laboratory Winched bottom plate for float stowage, grounding protection, and forced deflation Self-Centering Tongue-and-Groove Shear Connection Cable/Winch system for pulling together Partially Inflated Float Optional Folding Truss for Section Stiffening Stowed Float Lateral stability of floats achieved through float-to-float contact Design Details Side View Individulal Units Units as a Stiffened Section

Geotechnical and Structures Laboratory End View SYM Outer skin/deck 12" min. depth at Midspan Wheel/track line Limits Wheel/track line Loads Buoyancy Forces Main Longitudinal Girder Transverse Floorbeams ~4' o.c. Transverse Cantilever Beam for Buoyancy Forces ~4' o.c. Unit Design