Key Questions to Ask When Ordering Lattice Girder

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Lattice Girders and Steel Arches

Lattice Girders have been developed for special demands in the field of Tunneling. The system has been extensively tested and used successfully for numerous tunnel projects throughout the world.

Lattice Girders ensure an immediate support in the open span area. Contrary to standard solid-web girders, Lattice Girders are entirely integrated in the shotcrete lining; porous zones and shotcrete spray shadows are avoided.

The load-bearing capacity of Lattice Girders has been investigated in terms of various loading tests and by numerical analysis. Flexibility regarding geometry and bearing capacity characterizes this passive support system for underground applications.

Look to Jennmar Civil for quality USA manufacturing and development of ground support elements. We provide designs and products for Lattice Girders used in SEM/NATM construction.

Fields of Application:

• SEM/NATM excavation
• Passive support system for the excavated cross section
• Profile template for the excavation geometry
• Bearing for pre-support elements

Main Advantages:

• Immediate support in the excavation area
• Partial static support action even without shotcrete embedding
• Utilization as a true-to-form template for shotcrete application
• Easy and quick assembly
• Simple handling and installation by a small crew
• Optimum bond and interconnection with the shotcrete lining
• Simple adjustment and shaping to the excavation geometry
• Ideal bearing for spiles and lagging boards
• Spiles may be installed both above or through the lattice girders
• No need for investment in major equipment

 

Hi there fellow z-scale modellers,


I have changed my prototype from the Moffat Tunnel to the SP Coast Line depicting the Gaviota Trestle bridge. This to highlight the beauty of AZL’s SP Daylight passenger train consists. After having measured this bridge its length comes out to be 112cm (44”) in z-scale!

As I am examining the bridge and its measurements I noticed the lattice girders and started wondering how to realize this in z-scale. Currently I am thinking scratch build these lattice girders by using styrene beams and manual handy work creating the lattice pattern. Does anyone have any other ideas how to make these lattice girders?

Thanks in advance!
-Tiest


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Looking at the photos it look like laser cut would be the best way to go. You would have to hide the deck by sandwiching 2 to 3mm thick plywood between the laser cut ties on top and support trusswork underneath, then apply the bents, then cross bracing. I laser cut over pieces to make the trestle on the Timesaver Trestle module, and expect this would be a bit easier.

You need to build the module and terrain first, then the deck span, then you could measure the height underneath to draw up workable trestle bents. I can lasercut them with your provided dimensions.

Samtrees makes convincing palm trees like seen in that photo too, but they take a few months from order to delivery..

Robert,

Thanks for the offer! I might take you up on it!!!
I am expecting a book today called “ https://www.amazon.in/Closing-Gap-Bridges-Ventura-Counties/dp/Closing the Gap: The Coast Line and Its Bridges” by Nan Lawler.

Second I am awaiting a custom module; currently being created by our TTZ friend Stuart Denniston.


I am think to start a separate thread on this forum describing my endeavors, mistakes and learnings if that would be of intrest…
I suspect this project will take me several months if not a year+
Still got kids, my wife and a full time job that have my priority - in that order.

Thanks again for your offer to help!
-Tiest


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Ed,

Based on documented measurements ( http://www.modelingthesp.com/Structures/Bridges.html), the Gaviota Trestle seems 69’2” high which equates to 991mm in Z scale.

Forgive me for my ignorance but what do you mean with the ‘size of the girders’?

I am awaiting delivery of a detailed booklet, see my previous post that hopefully contains more detailed measurements.

Thanks!
-Tiest


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Hi there!

I am coming to the conclusion that my initial plan for this scratch build, using styrene beams and strips might not yield the detailed design I am looking for.

I know [mention]rray [/mention], you mentioned laser cutting. What would be the benefit of laser cutting over 3D printing?

As I am researching the world of design software I keep coming back to Adobe Illustrator (Paid) or InkScape (OpenSource). Does anyone have any hands-on experience in any of this software?

My main objective would be to design - structural elements - the bends, lattice girders etc.

Thanks and good weekend all!
-Tiest


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[mention]CNE [/mention] (Scott),

Thanks for confirming my thoughts. I started to get hands-on Illustrator and looks very promising. The interesting and complicated process is the thinking in ‘layers’. I do realize more and more that laser cutting creates great opportunities to build our custom z-scale world.

The example is exactly what I am looking for!! Couple of questions if I may:

1) Is the picture you included in the example the laser cut beam reflected in the Illustrator design in purple?
2) I assume the answer is yes, and would love to understand how this 2D looked on the laser cutter in 3D?
3) How did you achieve the ‘3D’ depth - is this one complete piece or multiple pieces/layers that you ‘glued’ together?
4) The lattice work depicted in Blue, can you share an example how that came out the cutter?

Thanks a lot in advance,
-Tiest


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So it's true you could go 3D Print as well as Laser Cut, and both methods could yield fine enough and strong enough parts. The laser cut bents would have to be assembled from layers of flat parts, and it's strength would increase as each layer is applied.

The same bents 3D printed in resin would be a lot more fragile, and if printed in filament would be stronger than resin but lumpy. Now that the size has been scaled to be 4" tall bents, I can say they would be pretty quick an easy to assemble each bent, then you just mount them under the trestle deck and apply cross bracing pieces.

Here are a couple bridges I lasercut from Polybak paper that survived the years of wear at train shows on modules. Once assembled you can see the z bracing and detail that you can get on your trestle bents:

Tiest,
The picture included is a MTL girder bridge that I will be using to model up the pink line work, it is an overhead traveling crane.
Yes you can grow 3D parts with openings and detail, without layering.
To Rob's point, I agree that the resin parts will be more fragile given the size of the bridge, but there are stronger resins and people have modeled big buildings using 3D resin.
The lattice work depicted in blue has not been built yet, but I was planning on layering it either in card board or plastic sheet.
The Illustrator will still be helpful modeling parts up for laser cutting.

Scott

I have a 30W CO2, and have found that things could be sped up with more power, so I would recommend the most power you can afford. Once you get used to using the laser, you will be able to make all kinds of great models.


Edit: I would go with the 20W now that I read the specs, 40W is faster but the 20W has better fine line resolution, yet can still do the job.