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"A truss for this situation would get too large" What do you consider too large? I doubt the trusses will be prohibitively heavy. As the structural engineer of record for a few mobile mining equipment structures, ditch the cables and use steel shapes. The only time there are cables is when...

COE EM 1110-2-2502, "Retaining and Flood Walls" link: http://www.4shared.com/file/47771412/f792c17d/EM_1110-2-2502-Retaining_and_Flood_Walls.html?start=

eea, I appreciate your interest, but we have decided to do the overpass. The railroad is used for transporting coal and is on private land.

Engineers, I appreciate you comments. We have decided to go overhead. It was getting way to complicated going underneath. The geotechnical engineer was proposing grout injections, but for some unknown reason did not address the slope stability risks. We lost confidence in his abilities, so we...

The tunnel is for vehicles. A bridge is an option but is not being looked at now.

Very good points cvq. Thanks. The tracks can not be allowed to settle. Groundwater not a problem. Choice of tunnel type is wide open. No expansive clay. Jacking a culvert may be possible if equipment is readily available. Location is South America.

No, it operates 24/7 for the delivery of coal.

Can't move the railroad. We have to do it with RR operational.

The RR has no jurisdiction in this case.

Anyone have example projects and/or design guide references or suggested methods of construction? It is through sandy clay type of material. The railroad has to be functional during construction of tunnel.

I designed a belt conveyor structure recently that had belt tension loads T1 and T2 of 60 kips each during normal operation and nearly twice that during motor startup. This produced significant loads on the supporting structure.

Univ of Texas Texas A&M LSU

I'd build an FE model of it and check nominal stresses (1 hour - done - next).

What I use is contained in EM 1110-1-2502, 29 Sep 89, Figure 3-27, p. 3-50. This document can be downloaded at the following URL: http://www.usace.army.mil/publications/eng-manuals/em1110-2-2502/entire.pdf "Sheesh. Some days it just doesn't pay to get out of bed."

Obviously, I calculated an incorrect lateral load to apply. The load should be design load of the compressive flange. Using the same example but changing the concentrated midspan vertical design load to 7 kip; 7 kip x 20'/4/0.95'moment arm = 36.8 kips. Then 2% = .736 kip lateral midspan load...

The plate can be considered a lateral brace (not torsional) because it will be acting as a diaphragm spanning 20' with a span/depth ratio of 10. Similar to DaveAtkins' recommendation, I recommend using 2% of the maximum vertical load as a lateral load on the plate. Evaluate the plate stress...

Here is an Machine Design article that might be useful in understanding when and when not to use peak stresses. http://machinedesign.com/ContentItem/61166/HowlinearFEAhelpsinfatigueanalysis.aspx "Sheesh. Some days it just doesn't pay to get out of bed."

Also from the same reference: "For torsional buckling modes, bracing must prevent twist of the cross-section to be effective." If it is a torsional buckling mode, it's twisting restraint that is needed not lateral. "Sheesh. Some days it just doesn't pay to get out of bed."

Excerpt from Lui's Handbook of Structural Engineering, "Torsional buckling occurs in members with doubly symmetric sections such as cruciform or built-up shapes with very thin walls. Flexural–torsional buckling occurs in members with singly symmetric cross-sections (e.g., channel,tee...

40818 - axial stiffness = AE, bending stiffness = EI, torsional stiffness = GJ, etc. With NASTRAN you can define a CBAR element with all these stiffness values as well as offsets and end releases. "Sheesh. Some days it just doesn't pay to get out of bed."