structural engineering for large sculptures

huangyhg

structural engineering for large sculptures
i need some advice before taking on a potetial client.  the client is an artist who creates kinetic sculptures.  it may verge on the mechanical side of engineering, but, in general, the pieces are attached to the top of 20' columns on foundations of course, and "spin" slowly with many pieces.  many of the pieces have been installed in public places, schools for that matter, with no engineering at all.  i told him that i would need to analyze the entire structure and create a drawing, for new work, before i could stamp anything.  i would appreciate any advice, stories, etc. regarding the structural engineering of public art.  he even said that there is no requirement that it be engineered at all, he just wants to make sure it stays up and no one gets hurt (and not hiring me just to take liability).  it is fascinating work, but i am approaching cautiously.
thanks in advance
from a liability standpoint i would tread carefully and put things in writing.  if you review the structure and it fails in some way you are responsible.
i have been involved with sculptures in various ways, but primarily it has been to design the foundation required to support it.  much lower liability as i exclude the design of the sculpture itself.
the buyer of the sculpture has not required the sculpture to be "engineered" on any projects to my knowledge.  the artist has just done what they felt was appropriate.  in the end i don't think that anyone would have wanted to pay someone to provide the engineering for a piece of artwork.
depending on the size of the sculpture. i saw construction of steel sculptures about 4 storey tall, which are comprised of metal pieces spinned up. the legs are supported by steel pipe piles. these sculptures and foundations must have been engineered.
truly fear is the major element of the previous engineers reluctance to do a design of a sculpture.  check wind and siesmic, (along with vortex shedding), snow/rain, dead load and live load, see if dynamics forces are present from unbalanced rotation or movement and solve this problem with joy and glee that you are part of a unique creation.
it would seem to me if the ibc is enforced in this municipality, that a permit along with the engineering and documentation may be required by section 105.1. fences greater than 6' high, and retaining walls greater than 4' high need permits.  and these are 20' high....  and in a public space....
thanks for the advice.  i sent a letter to the client today explaining that it won't be cheap and that he really should have his sculptures engineered.  i tried to explain my position in a way that wounldn't scare him off.  it is such a unique problem that i really do want to be involved.  we shall see.  apparently public "art" has yet to kill anyone, physically.  the absolute amazing aspect of this is the fact that this piece is at a public school, as are many of his smaller scale structures.  the one in question is actually about 30' tall with 12' long stainless steel needles spinning around the top.  and, not to worry, my letter was very very explicit in reccommending that the sculpture be engineered before it was installed.  
actually, public "art" has killed at least a couple of people
one of the earlier art works that had to be engineered is picasso's 'horse' in chicago. enlarged from a much smaller sculpture the artist had made.an interesting project. that of course is on the ground. elevating it and rotating it will multiply the problems !! re  
an artist like this is usually a crafty guy that is more like leonardo da vinci than a silly painter.  they are guys that have an uncanny ability to see structures and blend them with art.  i like artists like this.  i think he should have the structure analyzed but i would be you'd find his design conservative and quite intriguing.  re  
these things always take longer than you expect, mainly in the difficulties with explaining to a non engineer/build person what needs to be done to get it right.
try to get involved early so that you can make sure that what they are proposing is feasible.
also, make sure that you have the option to pull out if the artist is unwilling to meet your requirements.
i would explain to the artist that if one of his pieces did ever fall down and injure someone, he would probably never get a commision for one again.
i agree with csd72 but be diplomatic. that is why i would first check with the building official and lay most of the blame on the bo.  then you can come at him from the back door with what needs to be done and not look like the bad guy.