×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

concentrated load on old floor
2

concentrated load on old floor

concentrated load on old floor

(OP)
Hi, am looking for some advice concerning how to spread a concentrated load onto the ornately marble tiled floor of a ballroom in a Stately Home (it's an expensive floor!). The loading is from a tree (not a Christmas Tree ! ) which is to be temporarily erected on the floor for the purposes of filming a particular scene in a TV Drama. The tree weighs 4 tons. My initial thoughts are to use a steel I section, probable a 203/203/46UC seated on the floor and extending a width in the order of 4 metres to correspond with the spacing of the support beams beneath the floor. The concern I have is that there would still be a concentrated load beneath the center of the beam, as the beam attempts to defect under the load. Is there any easy way of determining the nature of support pressures beneath the spreader beam. Thanks, Tom

RE: concentrated load on old floor

If you can, it might be simpler to shore the floor from below. Otherwise you need to consider both strength and deflection.

RE: concentrated load on old floor

Why don't you provide a gap between your spreader beams and the floor - and have the beam span across the slab area and rest on thicker plates positioned directly over the floor beams below?

That way, as the spreader beams are loaded they would deflect downward a known amount - but never touch the marble tile. And all the load would go directly onto the floor beams (through the tile in direct bearing) and this would minimize the flex in the floor slab - possibly minimizing stress in the tile.

There would still be deflection in the main floor beams and you would have to analyze those to see if their deflection would be within limits to avoid cracking the tile.

RE: concentrated load on old floor

Hope you have a GREAT contract on this job stating NO GUARANTEES. There are TOO many unknowns when it comes to tile installation, and marble is especially brittle and poor in tension.

RE: concentrated load on old floor

How would you balance a tree on an 8" wide beam?

RE: concentrated load on old floor

Very carefully...

Mike McCann
MMC Engineering

RE: concentrated load on old floor

I am with Triangled as we used to do that when we rigged heavy machinery; and when we had multi floor below, we would shore all the floors below the heavy machinery that we moved on rollers.

RE: concentrated load on old floor

If it's an old Stately Home with a marble-floored ballroom, it's likely that the floor structure is built off heavy timber beams and finished in timber boarding, which then supports a bedding compound for the tiles.
If the steel beam was to be supported clear of the floor, spanning across two main beams, load will obviously be applied somewhere. Even if it could be shown that any existing main beams could support the load without undue deflection (whatever value is taken for that - who knows?), the bedding of the marble will be an unknown quantity.
Make sure your PI is up-to-date.

RE: concentrated load on old floor

(OP)
Thanks to all for the comments, really useful in focusing my direction. Had already decided that propping the principal timber beams from beneath and raising the support structure a little above the floor, to cater for deflection of two UCs would be a way to go, however, as you have mentioned there are still unknowns, especially the uniformity of the bedding material between the top of a (presumed) timber floor structure and the tiles.
Also, the excess on my PI would be greater than the fee I would receive. Have decided therefore to say that I can provide a scheme such that the floor does not collapse, but that I an unable to guarantee that the marble tiles could not possible crack. Again, thanks.

RE: concentrated load on old floor

Support it on a hovercraft. Sounds like your budget won't allow for that.

RE: concentrated load on old floor

Very smart to make no guarantees about the floor, only certify the structure. Too many unknowns. Tile cracks for all kinds of reasons, and marble has pretty poor tensile strength and in my experience cracks fairly easily, especially if there are veins in the tile.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources