How do the columns in the 'magic mountains' sculpture stay up?

Question

I am reading this story on artist Ugo Rondinone's sculpture in the Nevada desert (Building an Artist’s ‘Magic Mountains’ to Draw Visitors to the Desert) and simply wondering (as an artist myself): how did they make those columns stay up?

I didn't see any information on dimensions but from the photo with the artist below, one might guess that these columns are abut 25 feet high?

Assuming there is a solid concrete footing for the columns to stand on and some preparation of the "joints" between the stones:

• Is the weight of the stones enough to keep them stacked and resistant to wind and weather (as such weather as there might be in the desert)?
• Is it likely that the stones are drilled to incorporate some steel armature?

I understand that the stones could just be balanced, but given that this is a funded and likely insured project, I find that hard to believe likely.

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Answer 1

This marketing video shows moments of their construction.

• At 0:40 you can see them all upright. They aren't painted, but you can tell it's the same installation.
• At 1:37 and 1:46 you can see guys drilling into the boulders
• From 2:16 to 2:24 you can see the base is also being drilled and, most clearly, steel rods are being slid into the rocks.

So it is clear that the rocks are indeed incorporating steel reinforcement at the joints to avoid toppling over due to wind. Whether this reinforcement runs through the entire column or if the steel exists only around the joints is hard to tell. The former may be surmised by the length of the rods being inserted in the video, but the latter would be far easier to execute.

Answer 2

I do this for a living and I would certainly say that having a single steel rod running the full height of the sculpture would be the idea way to do it.

This method means that all of the major loads on the structure apart form its own weight in compression are supported by steel.

If you have individual pins for each joint means that any side loads are transmitted into the stone as shear of bending loads which is far form idea for natural stone (or even concrete for that matter).

Another very important consideration is the effect of water ingress into the structure and how this could cause problems with freeze/thaw cycles and corrosion.