Is my Conference table wobbly? 1

[aszx.6409]

Hi people,
I've designed this conference table that is 3.6m x 1.3m it has 4 inclined tapered legs which are attached to two beams, I want to know if this design is stable or it will be a wobbly conference table?
Thanks

engineers?

 

[jayrod12]

I feel like furniture is more of those, build it and check it out type things. Because I've seen some extremely thin table framing work adequately in the field. And alternately, I've seen some real robust looking members be extremely sloppy based on connections.

 

[drawoh]

aszx.6409,

It all depends on how accurately your feet match your floor, which may or may not be flat.

How flexible are your table legs?

--
JHG

 

[LittleInch]

Those legs look very slender and subject to sideways flexing so rotating around the middle of the table.

Also why the gap in the sub structure at the mid point?

Feels like anyone leaning on it in the middle is going to make it flex.

dimensions and materials of the elements would help....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

While the legs appear to be overly skinny, their flexure may allow the table to self level through its own load on the legs. Nevertheless, lots of tables have adjustable feet to level out uncooperative flooring. 3.6 m is a rather long distance to only have two legs.

I should point out, though, I and a coworker spent about an hour standing on a conference table a couple of weeks ago, installing and fiddling with an overhead projector, so, hopefully, your load analysis has accounted for such a scenario.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[aszx.6409]

How flexible are your table legs?
None, legs are made of bamboo panels which are pretty stiff (even more solid than plywood)

 

[driftLimiter]

The material may be stiff naturally but cut down to such a slender section you could see bending in those legs. Its good have battered them out on the diagonal, but still looks a bit wobbly to me (granted I am normally looking at heavy things like buildings ) I like what @jayrod says, build it and see!

 

[aszx.6409]

Feels like anyone leaning on it in the middle is going to make it flex.

dimensions and materials of the elements would help....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I am really sorry I am not familiar with forum stuff and I just don't know how to exactly reply to someone,
about the middle joint I think I should listen to you and make it in one piece.

table legs dims: 2cm thickness, 100cm length, base width: 4cm , top width 8cm

 

[aszx.6409]

 

[LittleInch]

Replying normally you just cut and paste and put into quotes

@aszx
"I just don't know how to exactly reply to someone" - it's not like WA or some other forums so you normally need to add the persons name in front and just copy in the relevant sentence.

"Remember - More details = better answers
Also: If you get a response it's polite to respond to it."

This is just my signature line - don't take it personally!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BridgeSmith]

The material for the legs may be strong enough, but they're too slender (length to thickness ratio is too high), and they will buckle under very little load.

Also, getting adequate strength in the attachment of the legs to the frame will be difficult, if not impossible. You'd be pushing the limits of the material strength of steel at the attachment point of the legs. I don't see how it can be made strong enough with any kind of wood, even bamboo.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[jayrod12]

I don't see how it can be made strong enough with any kind of wood, even bamboo.

Oh I've seen many a wood table, so the thought of using bamboo doesn't concern me as much as it may a bridge engineer

But the concern about connections is still valid and I share that same concern. I'm not sure how you're going to get the fixity you're expecting.

As indicated IRStuff, conference tables are notoriously abused as stepping stools and scaffolding in the offices I've worked in. I'd be pretty hesitant to put 500 lbs axial load on a piece of bamboo the size of a four-foot long 1x4 much less once you've thrown in the bending due to eccentricity. I'd bet you'd want to be into double that thickness. Or at least tapering to something thicker near the top.

 

[MotorCity]

Yes, I can say for certain that it will either be stable or "wobbly" (i.e. "unstable" if we are using structural jargon).

From a theoretical standpoint, it will be unstable if the number of members + the number of restraints is less than 2x the number of nodes.

I am guessing that you are more concerned about the lateral movement or sway of the table more than the theoretical stability.
What is your criteria for "wobbly"....deflection? vibration? how much or how little? Is there an ASTM on the serviceability criteria for furniture?

 

[BridgeSmith]

Oh I've seen many a wood table, so the thought of using bamboo doesn't concern me as much as it may a bridge engineer

I've seen alot of wood tables, too, and I've built a few. I was referring to wood construction in general, but to the size of the legs on the table shown. I know bamboo is a very strong wood, but I don't think it's strong enough to stabilize and support the table in the configuration shown.

Btw, my frame of reference is probably more from my experience building furniture (and repairing poorly designed pieces) than being a bridge designer.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[aszx.6409]

I am concerned with 3 things:
1. tipping over at the middle of the table due to lack of legs at the middle
2. because the legs are not fixed to the ground or to each other(frame like structure) bending at the middle of table will be too much(or legs will buckle). Considering, the fact that I make the beams in one piece (h=8cm,w=2cm,l=240cm).
3.the joint section between legs and beams under table top should be very strong, even though, making it out of those panels is not easy!

 

[jayrod12]

Using essentially eight-foot 1x8s as beam material likely will not be sufficient. Again this comes back to IRStuffs comment, 500lbs on a single piece that thin is not going to be enough.

I feel like we're being a bit misled on this project. We aren't here for free designs, we're here to help where we can with specific issues. You'll need to run the numbers, or build prototypes and test it, to be truly confident in the design.

The guys here have pointed out some concerns regarding the design, it is your job as the designer to dig into those concerns a bit deeper and determine if your own design is adequate.

 

[Tomfh]

Legs look too flimsy. It looks like it lacks torsional stability.

 

[XR250]

I doubt most conference tables are engineered. Most likely they are constructed based on past experience or trial and error.

 

[JStructsteel]

If you gonna build a table, build a table!

 

[SnTMan]

This is more like a subject for the forum1528 Forum, I'd say...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand