Compression Strength of Cast Iron Columns?
Compression Strength of Cast Iron Columns?
(OP)
Hi,
What is the accepted compression strength of a Cast Iron column?
We have a job coming up that we need to attach our beams to old existing cast iron columns.
I need this information for modeling purposes. (Etabs)
What is the accepted compression strength of a Cast Iron column?
We have a job coming up that we need to attach our beams to old existing cast iron columns.
I need this information for modeling purposes. (Etabs)





RE: Compression Strength of Cast Iron Columns?
Solid? Almost certainly not, but you need to actually verify EXACTLY what the interior of the old column IS .. Not what you think it is or what they "usually" are or even what the second and third and 4th one are. EVERY casting could be different because there is no checks or guarantees in the old metal. And, unlike mass-made parts, every one is hand-tamped, hand-filled, hand-cooled and broken out from the mold. Assuming they all used the same mold even. You could have 14 or 48 columns, and not know that 12 of them were near-breaking the whole time, but never quite got stressed enough to actually crack.
Also, the casting attachment needs to be checked, it will be difficult to weld to the cast metal, to drill and bolt to them, or to do much of anything but load them perfectly vertically. Metal variations from casting to casting might not change too much, but each pour could be different. 8 good metal (stronger than expected), 16 average, and 8 poor for example.
RE: Compression Strength of Cast Iron Columns?
I suspect many cast iron columns as you are talking about later were however perhaps designed via what was called the "New York Building Law Formula" that went through some gyrations over the years as explained in the pretty good article at http://cenews.com/article/8632/cast-iron-a-histori.... This law was sometimes simplistically expressed with a form e.g. circa 1915 as:
Unit Stress = 9000 -40(L/r) (with the output I believe in psi)
In the first half of the 1900's such columns, often round shaped [for all-round (so to speak) efficiency] may have been cast either vertically in pits, or a little later on centrifugally (with the latter portrayed as stronger iron and superior to the old pit-cast, and I believe with reasonable quality producers improving on at least most issues expressed by the previous responder). The point of where possible preferring other means of attachment than welding is certainly well taken.
The development of ductile iron in the mid 20th century provided a material with several times the tensile strength of gray cast iron, but still retaining an apparent compressive yield strength up to 20% higher than its 42,000 psi minimum yield strength (that incidentally also in perhaps non-obvious fashion gives rise to a great apparent bending yield strength of approximately 72,000 psi or so for ductile iron). As structural members centrifugally cast ductile iron piles and poles are used in the present day rather widely internationally, and huge quantities of ductile iron tunnel liner plates were also used to construct the Chunnel, or world's longest undersea tunnel just a couple decades between England and France, largely as a result of these strengths along with substantial ductility. Flanged ductile iron piping is also used in the present day as single pipe, and with special gasketing even longer "long-span" pipe beams.
I guess future generations will see if some other "modern" building materials in the long run provide comparable and as cost-effective service. All have a good weekend.
RE: Compression Strength of Cast Iron Columns?
RE: Compression Strength of Cast Iron Columns?
I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)
RE: Compression Strength of Cast Iron Columns?
http://www.engineershandbook.com/Tables/graycast.h...
RE: Compression Strength of Cast Iron Columns?