Structural Engineer Comments Please

[Fruit Trader]

Tear it down before it becomes headline news.

[Enoon]

 

OP, If I were you I'd be out buying a pair of these right now:

 

 

They should do until the TVF Design and Engineering Committee comes up with the definitive solution.

 

 

Edited May 24, 2020 by Enoon

[carlyai]

18 hours ago, Crossy said:

Too late now I know, but I would have used steel verticals. No issue with bending moments causing tension cracks then.

 

Two U sections welded back-to-back so there's no hollow space to fill with water and rust out.

 

I did think they would use the steel for the verti

cles, the same as they used for the rest of the structure. We still have lots of steel left from the pool shuttering. Don't know why they used the concrete posts. Maybe they thought the concrete posts stronger. 

[carlyai]

7 hours ago, Fruit Trader said:

Tear it down before it becomes headline news.

That would be dangerous. You've never seen my wife set up her pyramid with sticky rice and chicken feet and casting spells on people that really p her/us off. I asked her why non had died and she pointed out that they are sick or have lost everything...which is true. 

[bodga]

Stick two steel  legs here,  no cantilever but it  wont  fall down wind  bougainvillea around them

[carlyai]

19 hours ago, Bramley said:

That would do the trick.

 

18 hours ago, sometimewoodworker said:

This is what I mean either blue or red.

 

Actually I think that Crossy has your answer or inspired it.

 

add a c section to the back of each concrete post with the back to the concrete. Weld it at the top and bolt it in 3 or 4 places in the length. That will sufficiently reinforce the concrete and will not make any significant change to the look

I think I will go and have a look where they make these concrete posts, see how strong they look. They are in a .5 x .5 m concrete foundation. Probably not enough. 

[carlyai]

18 hours ago, Kwasaki said:

That's a fine structure nothing much for winds to do any harm.

As long as the concrete post footings were concreted in correctly it's OK that would be the only thing to be concerned about.

You don't say how that was done and how deep they were so I cannot comment further.                

Evidently the footings are about .5m square. Aggregate about 1" cement and sand mix. Maybe should have been 1m3?

[bankruatsteve]

32 minutes ago, carlyai said:

Evidently the footings are about .5m square. Aggregate about 1" cement and sand mix. Maybe should have been 1m3?

What is your concern?  That load is nothing compared to a 2-story house.

[sometimewoodworker]

23 minutes ago, bankruatsteve said:

What is your concern?  That load is nothing compared to a 2-story house.

It has to withstand a bending force not compressive force.

[carlyai]

13 minutes ago, bankruatsteve said:

What is your concern?  That load is nothing compared to a 2-story house.

My original concern was that I know nothing about cantilever construction and wondered what was the use of all that bracing at the top of the structure, between the vertical columns. How was that going to make it a strong structure as at certain times of the year we have very strong winds going in all directions. Seems like people think that wind is not a problem and the strength of the vertical supports and footings could be a problem. Now I know more. ????

[bankruatsteve]

35 minutes ago, sometimewoodworker said:

It has to withstand a bending force not compressive force.

In theory, there is no lateral (bending) force at the fulcrum.

 

BTW:  the "theory" is what I recall from a semester of bridge building in college (it wasn't called that but pretty much all we studied).  Lots of trig and diff-eq.  These days, I have my fair share of brain farts so whose know?

Edited May 25, 2020 by bankruatsteve

[Fruit Trader]

3 hours ago, carlyai said:

That would be dangerous. You've never seen my wife set up her pyramid with sticky rice and chicken feet and casting spells on people that really p her/us off. I asked her why non had died and she pointed out that they are sick or have lost everything...which is true. 

To reduce the chance of spells being cast you must first induce some fear.

 

E.g.

 

[bankruatsteve]

^That is obviously a poor design and not engineered.

[Fruit Trader]

20 minutes ago, bankruatsteve said:

^That is obviously a poor design and not engineered.

There is nothing obvious in the photo other than it failed. It was engineered but the engineer failed to include earthquakes.

[bankruatsteve]

2 minutes ago, Fruit Trader said:

There is nothing obvious in the photo other than it failed. It was engineered but the engineer failed to include earthquakes.

Well, it's obvious to me (I did pass professional engineer exam 50 years ago - but that wasn't my interest).  No way that was engineered properly, IMO.

[Mama Noodle]

3 hours ago, bodga said:

Stick two steel  legs here,  no cantilever but it  wont  fall down wind  bougainvillea around them

Alternate choice: stainless wire rope and turnbuckles for a more aesthetic, clean tie back. 
 

Can do a pair in the back as well, no welding and no drama for a full tie down. 

[Fruit Trader]

5 minutes ago, bankruatsteve said:

Well, it's obvious to me (I did pass professional engineer exam 50 years ago - but that wasn't my interest).  No way that was engineered properly, IMO.

Then maybe you should explain why it is so obvious from the photo. Please feel free to include a diagram and some calculations.

[bankruatsteve]

1 minute ago, Fruit Trader said:

Then maybe you should explain why it is so obvious from the photo. Please feel free to include a diagram and some calculations.

Why should I?  That photo is not the topic and appears to be poor design.  The OP's project appears, IMO, to be a good design.  And, calculations without specs would be meaningless.  ????

[Fruit Trader]

11 minutes ago, bankruatsteve said:

Why should I?  That photo is not the topic and appears to be poor design.  The OP's project appears, IMO, to be a good design.  And, calculations without specs would be meaningless.  ????

In other words you don't have a clue. ????

 

But you are correct by saying the photo is not the topic, its just part of some comment made in jest.   

[Kwasaki]

4 hours ago, carlyai said:

Evidently the footings are about .5m square. Aggregate about 1" cement and sand mix. Maybe should have been 1m3?

Without a site inspection my suggestion would be as rough sketch shows if there's any doubt of frailer, as for the present future monitor the footings for movement & any cracking of the concrete posts..

[bankruatsteve]

I don't know why you all think the structure needs more support?  A properly designed cantilever does not need additional support.  Whatever.

[Metropolitian]

2 hours ago, bankruatsteve said:

I don't know why you all think the structure needs more support?  A properly designed cantilever does not need additional support.  Whatever.

[Yellowtail]

You could just hang some heavy pots on the back to counter-balance it.

[motdaeng]

of course, this solution is not perfect, but it would solve some problems ... 

[bankruatsteve]

58 minutes ago, motdaeng said:

of course, this solution is not perfect, but it would solve some problems ... 

 

What problems? 

[RangerP703]

On 5/25/2020 at 11:52 AM, bankruatsteve said:

I don't know why you all think the structure needs more support?  A properly designed cantilever does not need additional support.  Whatever.

You think what the OP posted has been properly designed and engineered ?

[bankruatsteve]

54 minutes ago, RangerP703 said:

You think what the OP posted has been properly designed and engineered ?

It appears that way to me. Yes. 

[carlyai]

9 hours ago, bankruatsteve said:

It appears that way to me. Yes. 

 

9 hours ago, bankruatsteve said:

It appears that way to me. Yes. 

That's good to know. It's really difficult to know just by looking at the structure. From the comments it seems to me the weak points are the vertical posts (as not sure how much steel and strength concrete they are made of). Mainly because of the bending motion.

Will see what happens as wifey loads it up. I can definitely see it getting some flashing lights ...and a windmill would look nice. ????

[motdaeng]

On 5/26/2020 at 7:00 PM, RangerP703 said:

You think what the OP posted has been properly designed and engineered ?

 

On 5/26/2020 at 7:55 PM, bankruatsteve said:

It appears that way to me. Yes. 

that is a good one ????  

in thailand everything appears to be properly designed and engineered, isn't it?
that for sure is not what i have experienced with thai builders ...

 

 

Edited May 28, 2020 by motdaeng

[vogie]

I think a lot depends on whether the concrete was delivered or mixed by hand on site. If mixed by hand some workmen over here can be a little shy with the adding of the stone aggregates.

I have observed this when I had a kitchen extension fitted, I had to insist that they added stone to the mix.