ENGINEERS: I need your assistance!

[tony barnhill]

I'm planning to build overhead storage for my 3 Midgets (a '76, a '74, & a '63)...it'll go perpendicular over 7 other MG's I have stored in my garage...floor to ceiling space is enough so that the cars will be about 6' up in the air....the building is 44' long at that spot & I'm installing an overhead garage door in one end...so, about 36' would be used for the cars...
...what I'd like to do is use a series of 4x4 wooden posts with 2x's between them supporting some type of metal u-beams that the cars would sit on....I'll use a pipe/metal ramp system at the end that could be lowered on an angle so the cars could be pulled up through the garage door using a small winch...
...this is a REAL engineer test!

[ 10-17-2003: Message edited by: tony barnhill ]</p>

 

[Guest]

I'm not an engineer, but I believe using steel I beams would be a better solution as you would need fewer posts and would therefore have more unobstructed floor space underneath

 

[tony barnhill]

Oh, you're talking about 4" round posts w/flat bases & metal beams welded across to support the U panel...what's the difference in that & wooden posts? seems that the spacing would be the same with 4x4 posts w/2x's bolted across & 4" pipe posts w/metal welded across?

That's why I need an engineer's opinion!

[ 10-17-2003: Message edited by: tony barnhill ]</p>

 

[MarkJ]

I saw a parking lot in the middle of Chicago that had a system like you describe. Four metal posts and a steel platform that road up and down on the posts using a simple winch. Lower the platform, drive the car on it, raise the platform with the winch, put in BFG bolts to hold it all up there, then drive another car underneath. Pretty slick.
I wonder if a company makes something like that? Maybe you could buy it instead of making it.

 

[tony barnhill]

Mark...there are lots for sale out there b ut they're wide enough for big US cars & take up too much space in garage....I want a long overhead ramp that's 1 piece & thought about an incline to pull the cars up....wanna make it real simple

 

[Gary Lloyd]

Tony, I have thought about this more than once!!! It is not a real good place to use wood, in my opinion, steel is better suited!! What is the roof system over it?? Can anything be supported from it?? Is there a wall at the end, and is it closed in or still open??

[ 10-17-2003: Message edited by: Gary Lloyd ]</p>

 

[Guest]

and another thought, will the floor handle the load centered as it will be over a relatively small area? i.e., the posts?

[ 10-17-2003: Message edited by: Chuck Cougill ]</p>

 

[tony barnhill]

oh yeah, that floor will hols a 747! thick w/wire mesh & rebar all through it!

 

[PC]

This is why they have structural engineers sign off on construction drawings. There are so many little details.

I'm not a structural guy but I sure wouldn't try to put cars on the ends of 4x4's unless there were an awful lot of them. Then there's the issue of how to attach the channels. Attachment points are always an area of concern and fastening of dissimilar materials requires careful consideration of all possible load conditions.

Wood can be made to work but there are good reasons why everybody uses steel for this sort of thing.


PC.

 

[MGA Steve]

Tony,

Are you going to store the Midgets end-to-end or side-by-side? Ie, will all of the the weight of 3 cars be on a single pair of steel I-beams (turned sideways to allow wheels into "slots") or steel channels or several pair? Obviously that will affect the size I-beam/channel you select.

As far as 4-4s vs. steel, I would recommend the screw-adjustable, round steel posts used in basements to support the center I-beam of the house (same application as yours, but supporting a static load--house--instead of a dynamic load--Midgets). That way, you have both greater load-bearing strength than wood and can adjust the post to compensate for slight irregularities in the floor. They are also readily available, at least in parts of the country with home basements, at your local Home Depot store.

Check the load-bearing capacity of the posts at the store, divide the weight of your cars by that number, then add at least 50% more for safety. Remember, you're going to be working under there, so don't skimp on posts. Hate to have you brush one with a car you are parking down below and have everything come tumbling down on top of you--extra posts mean extra safety in that instance.

You can attach these steel posts to the upper I-beam or channel with bolts and to the floor with bolts set in the concrete (some come with a floor plate or you may have to buy them separately). To prevent punching holes in your concrete floor, you could use flat steel plates or channels (if you can arrange them parallel to the cars on the bottom) beneath multiple posts to distribute the load.

You also need lateral support to prevent the whole thing from toppling. Use either cross-bracing and angled "buttresses" and/or tie the whole structure to the walls (preferable) or ceiling of the building. If you tie it to the building, you may be able to use wood for that purpose (not load-bearing, just prevents toppling).

The angled ramp will theoretically allow you to use a winch that has much less pulling power than the weight of the car (maybe an 800 to 1,000 pound winch), but you should probably double that just for safety. And make sure the winch cable also has a significant factor of safety and a pulley on the steel frame to prevent fraying.

Hope this helps,
Steve

 

[Kim de B]

Oh, Tony, does it never stop?

 

[tony barnhill]

Steve...lots of good info there...thanks...I'm gonna park the cars one behind the other in a straight line; wasn't gonna put the weight on top of the posts but instead bolt crossmembers to either side & lay the metal u-channel on top of crossmembers...was gonna 'shoot' anchors into floor to hold posts in place & add 2x along the length of the entire run at the top edges....

Kim...so many cars, so little space...Wray's trying to convince me I need his MGA coupe projects; I've still gotta get an '80 LE, etc, etc, etc

 

[tony barnhill]

Only problem w/steel posts is fabrication has to be exact so they'll bolt together....&, I don't want the whole thing to be any wider than 5'.

 

[Guest]

weld them in place and fab them in your shop. Don could do the welding and all you'd need would be a pipe cutter

 

[Bruce74B]

Preparing for retirement can be tough, Huh?

I agree with Chuck and Gary...steel is the way to go. I am not an engineer (although I will ask my son, who is an mechanical engineering student about it...he might be some help) but I do build things and have specs for load bearing capacities of lumber. According to my rough (and conservative) estimates, you would need 4x4 (pressure treated) every 4 feet, with 2x10 connecting cross beam (5ft span) to adequately support the total weight of 3 (at 1750 lbs each)midgets and two people for a total of almost 6000 lbs at a run (height) of 6 feet.

Clearly, steel is the way to go...but be careful with the jack posts described above. An adjustable jack post is designed for constant load and has the tendancy to shift with movement of a live load.

I would suggest that you check with a local steel manufacturer. In this economy, there are a lot of steelworkers willing to take on small jobs at a reasonable rate. Take a look at your trailer for deck ideas.

One more thing. I am not sure where you will be winching from, but if you are winching from anyhwere other than the structure itself, be aware of the lateral pressure of pulling a car onto the end of the structure on the incline. A counter force on the other end or adequate cross supports will be esential. Better yet, try to locate the loading winch to pull against the structure itself, without getting in the way of course.

Good luck on this one, buddy!

 

[MGA Steve]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Bruce74B:
you would need 4x4 (pressure treated) every 4 feet, with 2x10 connecting cross beam (5ft span) to adequately support the total weight of 3 (at 1750 lbs each)midgets and two people for a total of almost 6000 lbs at a run (height) of 6 feet.

Clearly, steel is the way to go...but be careful with the jack posts described above. An adjustable jack post is designed for constant load and has the tendancy to shift with movement of a live load.

be aware of the lateral pressure of pulling a car onto the end of the structure on the incline. A counter force on the other end or adequate cross supports will be esential. <hr></blockquote>

Tony,

I agree with Bruce's comments and I am an engineer. But not a structural engineer and heven't done any structural work in a long while (think slide-rule, not desktop PC).

The longitudinal load from pulling the car up the ramp is the reason for all the lateral bracing I mentioned earlier. Best solution would be to brace the non-ramp end of your 36-ft long "second floor" against the wall opposite your overhead door.

But you still need lateral bracing as well to prevent side-to-side "wobble" caused by putting a 1700-lb car on top of a 6-ft high "moment arm" (gravity really wants it all to just stay on the concrete floor). Last night I thought about it some more and you might be able to laterally support the structure with steel cables, eyebolts, and turnbuckles instead of lots of wood bracing or steel. It may look like a spiderweb, but it can be very strong (think Oakland Bay Bridge)

As Bruce mentioned, it is the clear span over your MGs down below that is the real problem with wood. Wood floor joists don't have to support a Midget, but are still 16 to 24 inches apart in your house. They can't be that close together if there is an MG parked perpendicular "downstairs."

Obviously, a custom-made steel strucure using welded I-beams and channel would work best, but, when I suggested steel jack posts and I-beams, I was thinking of you doing the work plus the cost. The posts will only work if they are not allowed to move at all. This means pipe welded between the posts as cross-bracing and substantial lateral support--end-to-end and side-to-side.

In retrospect, this sounds like a good design project for Nial's engineering technology students, not an engineer with 40-year old structural textbooks and short-term memory loss!

Steve

[ 10-18-2003: Message edited by: MGA Steve ]</p>

 

[19MGA60]

I will be happy to store the midgets in my garage in Florida!! Just leave me the keys

I will even pick them up!!

 

[StevenA]

Tony, I hesitate to start this but there are some good ideas here... but a few not so good. I am an engineer(civil) but I have not practiced that trade since acquiring the degree in 1972. I found a job in another industry and never looked back. My entire family (three older brothers, father, and four uncles of my family, not really "all") are civil engineers, mechanical engineers, steel building contractors and residential & comercial contractors. So, all that said; let me get some info together and see if I and the "team" can offer some solutions. For thought; 1. In most of the U.S. it is cheaper to build "out" than "up" so if money enters into the equation it should be considered, 2. Steel is better and sometimes cheaper than wood for this type project... but if you have large timbers available then it could go that direction. Wood, rots, wood sags, and wood is less uniform in strength than steel (ie wood can be soft in one spot and hard in another within the same timber). 3. an example of what can be done... the same "I" shaped beams that are used as support and as rails can also be the "U" shaped driving rails for the tyres to fit into where flat wood would nothave "grooves" in it for guidance.
Lots more info when I get it ... but without knowing a few more details it will be tough. Also you mention that the concrete is reinforced with mesh and rebar... that could be good but almost all "floors" are reinforced in that manner but only intended to hold 300/400 pounds per square foot (the weight of one car approx). Stacking two cars on top of each other might exceed that level. How thick is the slab in the middle..not at the footing? How thick is the footing? If the building meets code for being or becoming a two story then it will hae adequate support for your auto super-structure. What building codes will you have to meet in your area (you don't want to build something and have a code inspector drive by and tell you to tear it down (happened to my next door neighbor).
More later, Steve

 

[Gary Lloyd]

Hey guys, 3 Midgets only way about 4500 to 5000 lbs!! It is not really that bad!!! The 'point loads' can be looked after by cutting the slab and digging down to original bearing soil, even if they are 30"X30" pads!! Micro Lams or Tec Lams could be used, but believe me, steel would be easier!!! Winching would be a problem, or at least something to be dealt with, because it is easy to winch the first one, but the second and third become a problem, unless you have some set-up with ****** blocks and pulleys!! If you are winching to clear the first car you would be winching from below, and that would put a lot of weird stresses on everything!! Anyway, I don't think it is hard to do, but I think it does requiew a lot of thought!!! I am sure the most economical and strongest way would be with steel!!!!

 

[tony barnhill]

1. No codes or building inspectors to mess with
2. Wanna go up since my ceiling is 10'6 from floor & there's lots of dead space overhead!
3. Concrete floor is 6" thick w/18"deep x 8" wide footings around outside
4. Am thinking winching each car up from tow points on front bumpers instead of driving onto platform
4. Want to be able to walk under platform so don't want to block one side with angle bracing (plus there'll be 7 cars underneath
5. Can attach winch either to wall of building or front edge of platform
6. One side of platform will be against the rear wall of garage
7. If using steel, would prefer to bolt together