# Ask the Structural Engineer! **URL:** \ **Category:** In My Humble Opinion\ **Created:** [May 20, 2003, 7:34pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365 "2003-05-20T19:34:53Z")\ **Posts on this page:** 13\ **Page:** 7
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [July 3, 2012, 7:47pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/121 "2012-07-03T19:47:08Z")
zombie (4x) or no (because it is an old thread). is there a building code where you live? was a building permit had for your house? if so then it is most likely OK. a 5 foot cantilever doesn’t seem too unusual. ianastructuralengineer. of course you have snow, it’s building material. ---
**Author:** ![Fir\_na\_tine](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Fir\_na\_tine](https://boards.straightdope.com/u/Fir_na_tine)\ **Post date:** [July 3, 2012, 9:41pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/122 "2012-07-03T21:41:36Z")
> [@gfinner](#): > > I have a porch 9x5 at the front right side of my house. Directly above it is a bedroom. The joists of the bedroom cantilever out 5 feet over the exterior wall. The joists are 2x10s spaced 16 oc. This house was built in the 80s. Just wondering if that is structurally sound. In Canada so we get snow. I vaguely remember reading that the current building codes require that the joists be secured within the house for twice the distance that they cantilever out. So your joists should extend within the structure about 10 feet. IANASE either. ---
**Author:** ![gfinner](https://avatars.discourse-cdn.com/v4/letter/g/d78d45/32.png) [@gfinner](https://boards.straightdope.com/u/gfinner)\ **Post date:** [July 4, 2012, 5:33pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/123 "2012-07-04T17:33:14Z")
Actually it’s not considered cantilever the corner is supported by a 6x6 post. So the rim joist spans 9 feet and rests on the 6x6. How far can a 2x10 rim joist span before support ---
**Author:** ![Parking\_Garage](https://avatars.discourse-cdn.com/v4/letter/p/b782af/32.png) [@Parking\_Garage](https://boards.straightdope.com/u/Parking_Garage)\ **Post date:** [November 1, 2012, 1:02am UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/124 "2012-11-01T01:02:19Z")
Are parking garages built safe? particulary this one. I have heard firefighters call them death trapshttp://youtube.com/watch?v=hr3HTkkpvtU&default\_tab=comments ---
**Author:** ![MjF03](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@MjF03](https://boards.straightdope.com/u/MjF03)\ **Post date:** [March 30, 2013, 9:39pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/125 "2013-03-30T21:39:12Z")
Is is structurally sound to cut a hole in a twin T concrete warehouse roof to be able to have roof access from the inside ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [March 31, 2013, 2:52am UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/126 "2013-03-31T02:52:19Z")
Maybe we can kill this zombie by jamming an iron ring into its undead brain? ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [April 1, 2013, 3:09am UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/127 "2013-04-01T03:09:34Z")
> [@The\_Flying\_Dutchman](#): > > . . . And then there was the [Kansas City Hyatt Regency walkway collapse in 1981](http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse) > > Such a minor change. Such a major mistake. . . . Okay, zombie thread and all, but… I looked at that page, and scrolled down, to where they show the actual engineering detail, the difference between the plan and what was actually built. The plan has one single bolt going through a square beam. The actual building involved two bolts, one going up and one down. ??? Why would this make a damn bit of difference? To my (obviously untrained) eye, the support is exactly the same. The horizontal offset is very small; surely it wasn’t enough to cause meaningful torque? The static force vectors all seem to add up the same. What the dickens is the deal here? ---
**Author:** ![that\_darn\_cat](https://avatars.discourse-cdn.com/v4/letter/t/59ef9b/32.png) [@that\_darn\_cat](https://boards.straightdope.com/u/that_darn_cat)\ **Post date:** [April 1, 2013, 5:21am UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/128 "2013-04-01T05:21:41Z")
> [@culture](#): > > Right, I am dealing with a 19 foot deep transfer girder that is cracking. We tear into the structure and find SIX LARGE HAVC PENETRATIONS through the girder that are nowhere on the structural plans. Die HVAC people, DIE! Quoted for truth. that\_darn\_cat Construction Manager ---
**Author:** ![gaffa](https://avatars.discourse-cdn.com/v4/letter/g/e68b1a/32.png) [@gaffa](https://boards.straightdope.com/u/gaffa)\ **Post date:** [April 1, 2013, 7:22am UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/129 "2013-04-01T07:22:58Z")
> [@culture](#): > > Dang, a serious question and I can’t answer it. We don’t get a lot of frost heave here in Texas. As a matter of fact, we don’t get frost here. > > A structural engineer must understand his limitations and not give advice outside their area of expertise as normally lives are at stake. Seriously. A structural engineer’s error killed about 150 people in the Kansas City Hyatt Collapse in 1983. > [@Trinopus](#): > > Okay, zombie thread and all, but… I looked at that page, and scrolled down, to where they show the actual engineering detail, the difference between the plan and what was actually built. The plan has one single bolt going through a square beam. The actual building involved two bolts, one going up and one down. > > ??? Why would this make a damn bit of difference? To my (obviously untrained) eye, the support is exactly the same. The horizontal offset is very small; surely it wasn’t enough to cause meaningful torque? The static force vectors all seem to add up the same. What the dickens is the deal here? Practically everyone involved in the structure “helped” make this horrible disaster possible. The client, who wanted a structural element that would make visitors “gasp in awe”. The architect who designed something that would push the envelope if everything went perfectly. The structural engineer who produced a workable design, but didn’t make sure it was executed correctly. The steel supplier who changed the box beam from two u shaped pieces welded together in the middle of the sides to one that was two u shaped pieces welded together in the middle of the top and bottom - \*so the holes for the threaded rods would go right through the welds! \* And then the steel fabricator decided that it was too much hassle to have to thread nuts all the way up the rod from the bottom floor to the middle, so they modified the design, so all the weight of the lower bridge was on that nut…the one drilled through the weld. In theory, not a problem if the weld is perfect, but what were the odds of that given the Stooge level of competence up to this point? Oh, and the capper? On several of the joints? Washers were missing! They were not installed! And the inspectors missed all of these things. Which was especially shocking as there had been a huge structural steel collapse on the project shortly before. People should have served time for the level of incompetence involved. (I’m a little touchy on this subject. A good friend of mine directed the rescue operation and triage.) ---
**Author:** ![cougar58](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@cougar58](https://boards.straightdope.com/u/cougar58)\ **Post date:** [April 2, 2013, 5:26pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/130 "2013-04-02T17:26:19Z")
for automotive, aerospace, etc…mechanical parts, the first big player was SDRC I-Deas for FEA. It later became a very high end 3D solid model software as well. NASA used it for FEA early on; Ford adopted it for CAD CAE in 1997, forcing it on all tier 1, 2 and 3 suppliers. Then just a couple years later, Unigraphics (EDS) bought SDRC, only to forcefully merge it into NX, which = Unigraphics + SDRC I-Deas. This screwed Ford magnificiently. All their legacy data had to be remodelled. Keep in mind that EDS Unigraphics was GM’s platform (Chrysler was CATIA). I think Ford is going to CATIA (too pissed off to stay with SDRC -\> NX ). Ford bought something like 20,000 seats - largest software purchase at that time, only to have it obsolete via a buyout from a competitor. Siemens bought the rights to the old SDRC and keeps it going. I would have thought Ford would have bought SDRC for obvious reasons. ---
**Author:** ![cougar58](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@cougar58](https://boards.straightdope.com/u/cougar58)\ **Post date:** [April 2, 2013, 5:34pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/131 "2013-04-02T17:34:19Z")
there was a show just weeks ago on one of the science or history type channels. It was about the FEA on one of NYC’s most famous skyscrapers. Its the building that sits on four huge columns for the first 4 or 5 floors, like its on stilts. A 20 yr old female architectural FEA student, called the architect (after it had been built and moved in to) if, when he did his FEA calculations, did he consider the effects of high wind hitting the buiding at a 45 degree angle, versus perpendicular to one face? The architect froze in fear ! there was a hurricane forecasted several days away, and he knew this young woman saw what he overlooked. He quietly met with the buildings tennants and owners, and explained the issue. Without letting the residents know why, they quickly hired welders to add reinforcement plates in critical stress areas throughout the building, per the FEA model (which depicts high stress as red). They finished just in time, otherwise it would have fallen. Anyone else watch this episode, or know the name of the famous NYC hi rise? ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [April 2, 2013, 5:59pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/132 "2013-04-02T17:59:53Z")
> [@cougar58](#): > > there was a show just weeks ago on one of the science or history type channels. It was about the FEA on one of NYC’s most famous skyscrapers. Its the building that sits on four huge columns for the first 4 or 5 floors, like its on stilts. > A 20 yr old female architectural FEA student, called the architect (after it had been built and moved in to) if, when he did his FEA calculations, did he consider the effects of high wind hitting the buiding at a 45 degree angle, versus perpendicular to one face? > The architect froze in fear ! there was a hurricane forecasted several days away, and he knew this young woman saw what he overlooked. > He quietly met with the buildings tennants and owners, and explained the issue. Without letting the residents know why, they quickly hired welders to add reinforcement plates in critical stress areas throughout the building, per the FEA model (which depicts high stress as red). > They finished just in time, otherwise it would have fallen. > > Anyone else watch this episode, or know the name of the famous NYC hi rise? The [Citigroup Center](http://en.wikipedia.org/wiki/Citigroup_Center). And the version of the story you heard was exaggerated quite a bit. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [April 2, 2013, 6:07pm UTC](https://boards.straightdope.com/t/ask-the-structural-engineer/176365/133 "2013-04-02T18:07:58Z")
What do you think of houses made from old shipping containers? They are strong, hurricane resistant, and noise proof-would you live in one? [Previous page](https://boards.straightdope.com/t/ask-the-structural-engineer/176365.md?page=6)