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Posted: 9/1/2015 3:00:23 PM EDT
[#1]
4. To make guys like you ask why a hexagon vs a circle.
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Posted: 9/1/2015 3:01:01 PM EDT
[#2]
Quote HistoryQuoted: 4. To make guys like you ask why a hexagon vs a circle.  Well, it worked..  |
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Posted: 9/1/2015 3:02:02 PM EDT
[#3]
4. Cuz bees use hexagons to build honeycomb
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Posted: 9/1/2015 3:03:54 PM EDT
[#4]
Quote HistoryQuoted: Well, it worked.. Quote HistoryQuoted: Quoted: 4. To make guys like you ask why a hexagon vs a circle. Well, it worked.. <--- Engineer . |
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Posted: 9/1/2015 3:03:57 PM EDT
[#5]
All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides.
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Posted: 9/1/2015 3:19:26 PM EDT
[#6]
Quote HistoryQuoted: All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. |
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Posted: 9/1/2015 4:11:22 PM EDT
[#7]
Quote HistoryQuoted:
I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. Quote HistoryQuoted:
Quoted:
All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. |
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Posted: 9/1/2015 4:14:12 PM EDT
[#8]
Plenty of circular columns and pedestals too. Look at most any water tower base. No hexagons.
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Posted: 9/1/2015 4:23:08 PM EDT
[#9]
Quoted:
There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. |
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Posted: 9/1/2015 6:22:36 PM EDT
[#10]
Quote HistoryQuoted: I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. Quote HistoryQuoted: Quoted: There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. First, thanks for the info. Second it is amazing the variety of people on ARF and the multitude of skills. I hope to get a chance to ask the person again. Of course he is a dozer operator so he may not know the reason either. |
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Posted: 9/1/2015 6:25:39 PM EDT
[#11]
The engineers are getting a kickback from the concrete company for using less concrete. I'd blow the whistle on them if I were you.
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Posted: 9/1/2015 6:27:20 PM EDT
[#12]
Might be easier to taper a hexagon than a circular shape.
I think the largish windmills taper as they go up 
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Posted: 9/1/2015 6:28:11 PM EDT
[#13]
Quote HistoryQuoted:
I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. Quote HistoryQuoted:
Quoted:
There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. I learned something new. I would have thought that round shaped foundations would be harder to construct. However, that's probably because I suck at drawing circles. |
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Posted: 9/1/2015 6:30:23 PM EDT
[#14]
Quote HistoryQuoted: I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. Quote HistoryQuoted: Quoted: Quoted: All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. |
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Posted: 9/1/2015 6:31:57 PM EDT
[#15]
Quoted: There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four How could you represent the number of three hexagonal bases in a row? Hmmmm....could it be....Satan? (I can't post pictures from an iPhone or I would post the church lady here) |
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Posted: 9/1/2015 6:32:12 PM EDT
[#16]
Quote HistoryQuoted: Might be easier to taper a hexagon than a circular shape. I think the largish windmills taper as they go up This is just the concrete "pad" or foundation that the anchors the tower into the ground. I believe the tower bodies are round and do taper on the way up. He said the mounting studs are set 5' deep in the concrete and the tower base is lowered down on to the studs, then nuts hold the tower base to the foundation. |
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Posted: 9/1/2015 6:34:03 PM EDT
[#17]
I'd say it provides the same support base using less product.
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Posted: 9/1/2015 6:34:05 PM EDT
[#18]
Quote HistoryQuoted:
First, thanks for the info. Second it is amazing the variety of people on ARF and the multitude of skills. I hope to get a chance to ask the person again. Of course he is a dozer operator so he may not know the reason either. Quote HistoryQuoted:
Quoted:
Quoted:
There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. First, thanks for the info. Second it is amazing the variety of people on ARF and the multitude of skills. I hope to get a chance to ask the person again. Of course he is a dozer operator so he may not know the reason either. Yeah, there could be a lot of reasons for it. If the soil is really crappy they might have decided they'd rather have a spread footer instead of a deep footing. We usually prefer to go deep, the biggest one I've worked on was 9ft diameter and 90ft deep, but I've also been on lots of them in the 15ft diameter range and 40-60ft deep. Those turbines need a very large diameter, and depth depends on soil parameters. The problem with a spread footing is the differential settlement, meaning you have to make sure one side doesn't settle more than another side. Sometimes that means pretty extensive soil improvement on top of all the other stuff. It wouldn't be my first choice, but there are lots of factors involved. At the end of the day I don't really care as long as it can be done correctly by the contractor. |
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Posted: 9/1/2015 6:34:15 PM EDT
[#19]
Quote HistoryQuoted: This is it. I just did the calcs for a solid cylinder and a solid hexagon's torsion resisting moment with a 75ft diameter. The hexagon's was roughly 40% more, I didn't do the calc for hollow ones but I'm sure the hexagon is better there to one degree or another. Quote HistoryQuoted: Quoted: Quoted: Quoted: All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. I think we are talking about two different things. It seems like you are talking about the actual tower part. I am talking about the big ass chunk of concrete buried in the Earth that anchors the tower. |
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Posted: 9/1/2015 6:36:12 PM EDT
[#20]
Quote HistoryQuoted: I think we are talking about two different things. It seems like you are talking about the actual tower part. I am talking about the big ass chunk of concrete buried in the Earth that anchors the tower. Quote HistoryQuoted: Quoted: Quoted: Quoted: Quoted: All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. I think we are talking about two different things. It seems like you are talking about the actual tower part. I am talking about the big ass chunk of concrete buried in the Earth that anchors the tower. |
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Posted: 9/1/2015 6:36:56 PM EDT
[#21]
Quote HistoryQuoted: I learned something new. I would have thought that round shaped foundations would be harder to construct. However, that's probably because I suck at drawing circles. Quote HistoryQuoted: Quoted: Quoted: There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. I learned something new. I would have thought that round shaped foundations would be harder to construct. However, that's probably because I suck at drawing circles. There are some huge auger machines that can dig a round hole fast and deep. Makes sense to go round if you can find an auger big enough for the job. |
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Posted: 9/1/2015 6:42:35 PM EDT
[#22]
Quote HistoryQuoted:
I think we are talking about two different things. It seems like you are talking about the actual tower part. I am talking about the big ass chunk of concrete buried in the Earth that anchors the tower. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
Quoted:
All the points you listed are reasonable possibilities. I also wonder if the hexagon is more resistant to the forces placed on it by the windmill because it has flat sides. I also thought of that. I can't see that it would be any better or worse then a circle, but I suck at engineering and physics. I would think the circle would employ the same principles as an arch as far as strength and the way loads are distributed and dissipated. I'm guessing the hex forms are easier to set up, tear down and transport. I think we are talking about two different things. It seems like you are talking about the actual tower part. I am talking about the big ass chunk of concrete buried in the Earth that anchors the tower. You definitely are talking about different things. |
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Posted: 9/1/2015 6:43:06 PM EDT
[#23]
"The footing is more like a "mechanical device" than a ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdffoundation." |
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Posted: 9/1/2015 6:49:58 PM EDT
[#24]
Quote HistoryQuoted:
I learned something new. I would have thought that round shaped foundations would be harder to construct. However, that's probably because I suck at drawing circles. Quote HistoryQuoted:
Quoted:
Quoted:
There is a wind farm going up in my area and I have had a chance to speak to a few of the guys doing the install. One person I was talking to said that the concrete base was 75' in diameter and was hexagon shape. Of course once he left the shop the question hit me... Why hexagon shape? Some reasons I came up with was.. 1. Easier to form up straight lines then a giant round form. 2. Assuming the points of the hex were 75' across from each other, it would require less concrete then a circle. 3. Engineers love hexagons(?) 4. well I have no number four I design large power lines for a living. I actually specialize in foundations. Without seeing the design, I'd suspect 1-3 are pretty close. With smaller foundations we normally use round shapes because it is the easiest to construct with rotary tools. I learned something new. I would have thought that round shaped foundations would be harder to construct. However, that's probably because I suck at drawing circles. Think of this, anywhere from 18" in diameter to 20ft in diameter. 
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Posted: 9/1/2015 6:56:26 PM EDT
[#25]
Quote HistoryQuoted:
"The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build. |
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Posted: 9/1/2015 7:03:27 PM EDT
[#26]
They screw them in with a 75' SnapOn combination wrench.
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Posted: 9/1/2015 7:04:35 PM EDT
[#27]
Quote HistoryQuoted: They screw them in with a 75' SnapOn combination wrench. Now you have done it... Kcolg won't rest until he finds a 75' box end Snap-On |
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Posted: 9/1/2015 7:05:20 PM EDT
[#28]
Quote HistoryQuoted: Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build. Quote HistoryQuoted: Quoted: "The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build.  In fact page 45/46 here almost confirms it. |
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Posted: 9/1/2015 7:11:55 PM EDT
[#29]
It might depend on how many bolts are required to hold it down. If 6 bolts are needed, then a hexagon with a bolt at each "point" gives a wider fooprint to resist tipping than 6 bolts around a circle of equivalant material cross sectional area. E.g. it's a more efficient design in terms of amount of material used vs. strength.
When hundreds of bolts are needed, spaced inches apart, then circular is a stronger / more efficient design. I'm just talking out my ass, but that's a reasonable theory. |
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Posted: 9/1/2015 7:13:47 PM EDT
[#30]
Quote HistoryQuoted: And I agree.... In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf Quote HistoryQuoted: Quoted: Quoted: "The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build. In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf I just wanted the answer, I didn't want to have to do maths... |
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Posted: 9/1/2015 7:15:33 PM EDT
[#31]
Quote HistoryQuoted: Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build. Quote HistoryQuoted: Quoted: "The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build. The footings are poured in place, I am fairly certain if straight sides are chosen it is done to simplify concrete forms. A circular foundation would technically be the most efficient when taking random load conditions (ie winds changing direction) into account. |
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Posted: 9/1/2015 7:35:09 PM EDT
[#32]
not sure without more info, but... round is a bad shape when it comes to traveling through wind. they may have also gone Hex to help reduce vortices coming off the structure and effecting the blades of the mill.
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Posted: 9/1/2015 7:39:13 PM EDT
[#33]
Quote HistoryQuoted:
And I agree....
In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf Quote HistoryQuoted:
Quoted:
Quoted:
"The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build.
In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf As an electrical engineer, most of the reasoning behind what civil/MEs do is rooted in laziness. That's how I knew. |
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Posted: 9/1/2015 7:44:24 PM EDT
[#34]
Quote HistoryQuoted:
I just wanted the answer, I didn't want to have to do maths...
Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
"The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build.
In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf I just wanted the answer, I didn't want to have to do maths...
Then look at Fig. 7 on page 48 for a picture of wind towers with circular pedestals.
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Posted: 9/1/2015 7:48:42 PM EDT
[#35]
Quote HistoryQuoted:
As an electrical engineer, most of the reasoning behind what civil/MEs do is rooted in laziness. That's how I knew. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
"The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build.
In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf As an electrical engineer, most of the reasoning behind what civil/MEs do is rooted in laziness. That's how I knew. LOL. As a civil engineer, I can look someone in the eye and understand humor. 
Just remember, you can't spell geek without EE! (how can you tell if you are talking to an extrovert electrical engineer? He's looking at YOUR shoes!) |
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Posted: 9/1/2015 7:57:13 PM EDT
[#36]
I work for a crane company that works on wind towers, mostly 80-100 meter towers.
Never came across anything but circular pads for the towers, never have seen a hex pad. |
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Posted: 9/1/2015 7:59:34 PM EDT
[#37]
Quote HistoryQuoted:
LOL. As a civil engineer, I can look someone in the eye and understand humor.
Just remember, you can't spell geek without EE! (how can you tell if you are talking to an extrovert electrical engineer? He's looking at YOUR shoes!) Civil engineer my ass, you're MEAN. |
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Posted: 9/1/2015 8:19:34 PM EDT
[#38]
Quote HistoryQuoted:
As an electrical engineer, most of the reasoning behind what civil/MEs do is rooted in laziness. That's how I knew. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
"The footing is more like a "mechanical device" than afoundation." ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Wind_Turbine_Footing_Design.pdf Doesn't explain anything as to why octagon would be preferred over circle. I'm going with it's just a bit easier to build.
In fact page 45/46 here almost confirms it. https://icjonline.com/views/POV_Wind_energy_tower.pdf As an electrical engineer, most of the reasoning behind what civil/MEs do is rooted in laziness. That's how I knew. As an ME, I wouldn't be surprised if the structure was hex so the engineer just matched it. Not due to laziness though. Because engineers are anal and want things to "look right". Most likely, though, is that the hex shape is easier to form up above ground (likely round below grade) and uses less material to get the required footprint/bolt pattern, as already suggested. |
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Posted: 9/1/2015 11:29:31 PM EDT
[#39]
Easier to lay the reebar in more stable triangular orientations.
Uses less material. Easier to lay out stress cuts so the concrete cracks exactly where you want it too. I'm not an engineer, so my guesses are probably wrong. |
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Posted: 9/2/2015 5:22:04 AM EDT
[#40]
Out of curiosity, are there piers drilled at the outer most points of the hexagon? That would appear to be a simple way to construct the footing.
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