OT - Structural Analysis

Submitted by umjgheitma on March 29th, 2010 at 12:20 PM

I'm looking for some advice on a project I'm working on for a friend. He bought a piece of land that has a pretty steep valley (about 40 ft across and 20 ft down) on it but on the other side is more land to utilize. He wants to build a bridge to conveniently get to the other side. We were wondering what's a good piece of stress analysis software?

Also, there is another friend that wanted to see if there was any software that would compare vehicle frames built with like rectangular vs. tubular materials. If there's a program that encompasses everything then great, if not I would like your thoughts on software that will help with either section.



March 29th, 2010 at 2:56 PM ^

So a guy stops in a little farm town and as he checks into his hotel room, he asks the clerk where he should go to get a drink. The clerk says, "follow the little stone path that starts outside the back door, over the stone bridge, and on the other side you will see a little pub that the locals frequent. The man admired the beautifully crafted cobblestone pathway as he walked, and stopped in awe to admire the stone bridge constructed over the running creek. Eventually, he made his way into the dark little pub and sat at the bar near the only other patrol, a sad looking old man. "What is the problem, sir?" he asked him. Looking up, the man replied, "Did you happen to see that pathway outside?"
"I did." the man replied.
"I built that pathway. You would think they would call me Hank 'the wonderful pathmaker. But they don't"
"Oh," replied the man.
"Did you see the little bridge at the end of the path?"
"I did," replied the man.
"I built that, too. You would think they would call me Hank 'the wonderful bridgemaker. But they don't."
"Well, what do they call you?" the man asked.
..."You know, you f*&^ one goat and..."

-yes, I might be calling you a goat f*&^er


March 29th, 2010 at 12:27 PM ^

i know a great piece of software - its named "call a structural engineer"

i would guess your friend is building a bridge to get to a piece of land that is more suitable for typical construction. my advice, skip the bridge building and put that money into a really special building. a house in a ravine, up in the air - always amazing.


March 29th, 2010 at 1:57 PM ^

I'm a registered civil engineer, and I can't recommend that you tackle a bridge yourself.

One solution that's a little easier to handle (mentally at least) would be something like a corrugated steel pipe arch culvert. You can get them in very large diameters and you'll know they will hold up to vehicular loads as long as you install them according to the manufacturer's recommendations. Here's one supplier...



March 29th, 2010 at 5:37 PM ^

Civil Engineering, hence the structures. I'm no longer at UM though, as the switch from AERO to CivE wasn't worth the 3 more years of paying UM prices. Plus with the grades I had in AERO, I had generally lost focus on academics as quitting AERO broke me. First time I'd ever quit something in my life. I needed a change of scenery.

Back in Texas now, and I'm getting professors that, while less impressive on the resume, speak clear English and teach VERY well. My grades have improved immensely (probable 4.0 this semester), and my cost is about 10-20% what they were.


March 29th, 2010 at 10:21 PM ^

I guessed Civil, but structures classes are also required for Architecture majors as well. Do not feel bad for quitting something because its not the right fit for you. I went to school for three years for Mech. Engineering and decided to quit for an Architecture degree. I don't regret the switch, it's what I was meant to do.


March 30th, 2010 at 1:22 PM ^

Amen - my aero grades are dismal and I have a 215 exam tonight (so technically I should be able to provide insight to this bridge issue with my Matlab code from an obscenely long homework problem... if I had learned anything that is).

It doesnt help that I think the professor is secretly one of the South Park Christmas Critters. THAT CHIPPER AND EVIL.

Props for finding something that works better for you, are you at one of the bigger colleges in Texas? A friend of mine in aero transferred here from UT


March 30th, 2010 at 1:44 PM ^

Yeah, I passed 215. That's about all the good that came out of AERO at UM. I probably had the same teacher. Kabamba, he definitely was chipper for a 8:30am class. Not so much evil from what I recall, but those days are hazy at best now.

I'm at a satellite campus of UT (at Tyler). Smaller campus, everything around here is brand new, only the library hasn't been updated since 1997. School is only 36 years old, and was only a junior/senior campus until 1999. Smaller campus feel is definitely different, and probably for the best for me. Less distractions. The undergraduate student enrollment here (4,300) is only about 400 more than my high school was when I graduated. Plus our baseball team is a D3 contender from year to year, despite our coach/athletic director leaving after this year.


March 29th, 2010 at 12:50 PM ^

Coming from a soon to be architect, my advice would be to contact a local architect with a good reputation and ask them if the were interested in designing a few alternative strategies to a bridge. There may be some interesting ways of dealing with his particular site conditions that might have some very interesting solutions.

That being said, I would at the very least take my schematic bridge design to a trusted structural engineer to give it a look. Most probably wouldn't touch it for liability reasons, but if you can get an "off the record" opinion that would be great. You don't want to screw up on something like this, because it is a great safety/liability concern.


March 29th, 2010 at 2:10 PM ^

Is that a reference to a LEED eco-charette? Because if so, sign me up! On a serious note, though, if it is being used for any residential or industrial purposes, note that the bridge will have to be rated for any emergency vehicles (ambulances and firetrucks) that would need access. They are considerably heavier than a car.


March 29th, 2010 at 4:01 PM ^

I'll +1 you because I was only half serious.
40 x 20 isn't that much (if your estimates are correct).
You didn't mention any water (running or standing). Otherwise, a judicious use of culverts might help.
Any bridge capable of safely carrying vehicles across it is going to need some serious footings that could also be environmentally destabilizing.


March 29th, 2010 at 1:04 PM ^

I prefer a rope bridge a-la Indiana Jones. And be sure to make it just enough to carry the expected weight with no margins. It'll make it just that much more exciting.


March 29th, 2010 at 1:31 PM ^

Buzz Killington: (Hands MGOBoard a picture of a man riding a Penny Farthing bicycle.) Now, here's a fellow attempting to ride a bicycle. But he's having some trouble, isn't he? And do you know why?
MGOBoard: (Sighs) Why?
Buzz Killington: Because he's a Scot! (laughs) Now, who here likes a good story about a bridge?
MGOBoard: (Groans, lifts his glasses and rubs his eyes)

All In 4 Michi…

March 29th, 2010 at 1:37 PM ^

MSC/NASTRAN is industry standard. Unless you know how to use it, you'll spend 6 months learning the basics. Not to mention that getting the software will be a hassle. I'd suggest just pick up a basic structural mechanics book and build everything to handle an Abrams tank driving across it. Good luck


March 29th, 2010 at 3:39 PM ^

had a beautiful home about 40 feet from the street, a modest ravine in back with a creek running down the center. A heavy beam footbridge was at the end of the winding path on both sides of the ravine. On the opposite side of the ravine accross from the house was an indoor pool with all the amenities, showers, jacuzzi, and wet bar. His partner had a home on Lake Washington with a yacht that only occassionally went furthur than Huskie Stadium. I went to see the Michigan game. Forget the ravine and buy a yacht.


March 29th, 2010 at 4:28 PM ^

in the state of Michigan. I think your best bet would be to find someone who stayed at a Holiday Inn last night. They could help you out with this bridge thing, no problem....

And just for the record, I have reviewed the avatars for several of the Mgoblog regulars (Magnus, Goblue1065, Aquaman2342, jrt336, etc) and found them all to be quite structurally sound!!!


March 29th, 2010 at 5:56 PM ^

I've got some military field manuals for calculating load classifications, but I can't exactly put those on here. What kind of construction are you looking to use? Maybe I can help ya out, though a 40 foot gap seems kind of big to be spanned by an amateur in a safe fashion.


March 30th, 2010 at 7:55 AM ^

who, while not a civil engineer, had a degree in heavy machinery, and has run various steel recycling centers for on about 40 years. He's seen a lot of kludges in his time, to deal with issues in yards, and he had probably the best advice, which I can't disagree with.

If you're dead set on building a bridge across the gap, and doing it yourself, overbuild it. If you plan on it being strong enough to walk on, make it obviously strong enough to drive on. If you plan on making it strong enough to drive on, make it obviously strong enough to drive a tractor trailer on. If you think you need solid wood footings that go three feet deep, make concrete footings that go five feet deep. As long as you way overbuild it, you'll be okay.