Need HELP with WIP

[alienwar9]

Hey everyone,

I've finally gotten back to working on my big project, and have been working on the support underneath the raised part of the city.

This part needs to be stable enough to hold larger buildings with interiors, and scale to only holding roads. It also needs to be cost effective (aka, least amount of pieces, cheapest pieces possible).

This is something I need help with, and included is the lxf file with a temporary solution.

Building Support LXF

Any design ideas, concepts, or tips would be greatly appreciated

Don't mind the green pegs, its just for visibility. Also don't mind the second half of the building on the side, its just there for reference. The building is just for example, but larger/smaller ones will need support also. The height of the sidewalk and plates are exact and cannot be changed. Anything underneath is what should be the focus.

Key areas: Solid build, low piece count, low cost

I will use them as guidelines for the rest of the city also.

Here is my post for the city just in case (its a big post, lots of pics).

Edited March 19, 2011 by alienwar9

[DLuders]

Hey! You sure have an ambitious LDD project! I'm a Civil Engineer by profession, and noticed these problems with your model's basement support structure:

1) You need more Technic Pins (which you have colored green) on the 5x7 Technic Brick frames, so that the intersecting Technic Bricks don't sag under the weight of the building. As they are now, there are only Technic Pins on the very ends of the Technic Beams, and they will want to rotate unless secured with more Technic Pins.

2) You need an additional red 4x4 brick column along the right-middle part of your basement, to match the 3 columns in the center part of your basement.

3) You need to infill the front-right red column so that there is "load transfer" straight down the entire 4x4 width of the column to the ground.

4) The horizontal "tie straps" made from Technic Bricks that are midway down each red column do little to promote lateral stability. The 4x4 red columns are enough to transfer the VERTICAL loads, but the tie straps will not resist sideways movement (to resist earthquake seismic forces). You need DIAGONAL braces to prevent the unreinforced basement walls from "racking".

I'm wondering why you colored the columns red (like real bricks), when the left basement wall is grey (like concrete blocks)....

[alienwar9]

Woah! Thanks for the help so far! It's good to know I've got a skilled professional helping me out

Just to make sure I understand:

for #3, you mean to fill in the gaps on the columns like where the "tie straps" are, right?

Any ideas on how to place diagonal braces with Lego? My poor attempt at stopping lateral collapse was...well, a poor idea

I'd need a cost effective method, as most likely these buildings would be shuffled around on not-so-slippery surfaces that would probably cause them to shift and tumble

I have a larger building set on 4 32x32 baseplates, 24 stories tall, and I'd probably die if it fell. It needs serious support. Any idea if the current model, with column distances (with cross support, of course) is enough?

By the way,

The reason the columns are red, is that oddly enough, red bricks are the cheapest. Honestly, they will most likely end up being random colored as they won't be seen (though I will at least make the columns a solid color).

Also, later on I'll be working on double sided draw bridge roads, trying most likely in vain to manage motorizing them. Don't know if that is under your expertise, but I most likely will need all the help I can get (especially since I am working with a very small space, and an angled bridge. I never do things the easy way )

[DLuders]

Yes, in regards to item 3, you should fill in the gaps where the "tie straps" are. However, since those really don't prevent "racking", perhaps you could consider something different. Instead of having the tie straps attached MIDWAY along each red 4x4 column, you could use 32324 "Technic, Brick 4 x 4 Open Center" at the TOP and BOTTOM of each column. Since they have Technic holes on all four sides, they offer good anchor points to put DIAGONAL Technic Beams. I checked LDD 4.0 LU Mode just now, and those 32324 Technic Bricks are in the Parts Pallette (4th group down).

You could always test the strength of your "basement" support structure by building a prototype (without the Lego buildings above), and weighing it down with piles of books, or bags of flour. If it collapses during the test, you can add additional columns, Technic pins, etc. to support it.

If you want to build Lego Bridges, check out some of the designs on TEXbrick .

Edited March 20, 2011 by DLuders

[alienwar9]

Thanks again for the help! I took a look into the link you provided, and it helped a lot with the diagonal truss techniques.

Though I'm definitely not building any bridges of that size! Mine are tiny compared

[alienwar9]

Oh boy. After some hours of working on this thing, I've had little luck with the diagonal supports. It seems with only 16 (plus 2 plate) brick height, I don't have many options for triangles.

It seems that the ratio of brick height 5, technic hole 7, is causing a problem. I can't get even numbers worked out for a Pythagorean triple.

Geometry oddly enough has never been my strong suit.

The problem is in the mixing of brick height and technic pin hole distances. Supporting a brick height with a vertical technic beam is fine, but once a diagonal piece is needed, there is no easy triangle to make.

It looks like once again I need help!

[DLuders]

@ alienwar9: There is a technique whereby you can use 3794 "Plate, Modified 1 x 2 with 1 Stud (Jumper)" on top of the studs of the Technic Brick ends. The "jumper" plate offers a 1/2-stud difference in length, for a subsequent 1x6 or 1x8 Plate to bridge the gap.

Bricklink calls it the "Half-Stud Offset -- A building technique that allows a LEGO fan to build without regard to the standard alignment of studs on a plate. See also Jumper Plate", which is "A 1×2-stud LEGO plate with only 1 stud in the center. Useful for half-stud offset building."

Below is a picture of what the "jumper" looks like. In the blue image below, imagine that the lower two studs are the top of the 1x Technic Brick diagonal. On top of those studs, place the 3794 Jumper Plate. THEN, on top of the Jumper Plate, place a regular 1x Plate to span across the gap to another, adjacent Technic Brick built the same way. The gap between the two Technic Bricks are now 1/2-stud offset. I wish I could find better pictures, but maybe you can understand what I mean.

,

[DLuders]

@ alienwar9: There may be another, "more elegant" way of creating the diagonal braces for your basement/subway areas. Since Technic BRICKS come in even-stud lengths and Technic LIFTARMS come is odd-stud lengths, you could combine them to get different-length diagonals (to the nearest "whole stud" length). The Technic Liftarms would work better against the red columns and on the underside of the "floors", because they are 1 stud high (and not 1-1/3 studs high like Technic Bricks are). You could join the various pieces using 32449 "Technic, Liftarm 1 x 4 Thin", doubled-up to form a one-stud-thick assembly. The 1x4 Liftarms should have all of the holes filled with Technic Pins and Technic Axle Pins to prevent rotation.

Since the hypotenuse of the Right Triangles are likely to be some fraction of a stud length, you could use this special 53586 "Technic, Axle and Pin Connector Perpendicular with Extension" (pictured below). This 53586 part connects to the holes in the Technic Bricks and Technic Axles (via a Technic Axle Pin), and a Technic Axle is able to SLIDE inside the long tube to give a custom length. The other end of the axle can be routed through a 6536 "Technic, Axle and Pin Connector Perpendicular" (pictured below), and the axle could have Technic Bushes on both sides to secure it and prevent it from sliding easily.

I checked the LDD 4.0 LU Mode parts pallette, and these pieces are available. The 53586 part is known as "Fric. element, cylinder" near the bottom of the Technic Pins group.

[alienwar9]

I am always amazed at the creativity that Lego fans have! Thanks so much for the help!

I fear that all the angles might start to make the models unstable in LDD though, as I've just finished a section and it is already having problems running (and I already cut the city into sections to make it run better).

Most likely, I will test out the different methods for stability and see what is the minimum I can get away with in real life. I've tried out the different ways you posted to see if/how it works in LDD, but it will be much better to test it with weights.