Mar 31, 2008, 2:37 AM
I have been doing engineering research on new materials. When I reviewed all the threads here. Any suggestions? I am looking on data on the use of composites in high rise projects. I really want to see any structural replacements for steel and concrete.
Apr 1, 2008, 2:20 AM
I assume by composites you are referring to carbon-fiber, fiberglass, ect, seeing as concrete can vaguely be considered a composite. However, its unlikely you'll see any of the typical composites as a structural material, mostly due to cost, but also because they tend be be really strong in one direction and pretty weak in others. It can be layered to be fairly equally strong in all directions, but you sacrifice overall strength. They also tend to be quite brittle, which doesn't make for good building material.
Mind you, some of these materials may actually work structurally, but you still have to deal with the views of the engineer, so while it may mathematically work, an engineer may not feel comfortable with it, and won't use it. I've seen it a million times, "Why did you call for 2 inches of stitch weld every 6 inches if 4 inches every 6 feet work?" and they usually say something like "I thought it would look silly like that". If something doesn't "look right", it may not get used anyway, even if it is fundamentally sound.
As a side note, you might look at glass as a structural material, while not considered a composite traditionally, I remember reading something about it being used as a structural material.
Apr 1, 2008, 9:58 PM
Glass has awesome strength, but the kind of glass that can be used structurally is phenominally expensive.
Composites that can be utilized for actually building large scale structures are also phenominally expensive. You are seeing them in airplane construction predominantly right now. Hunt down the Extreme Engineering or Build It Bigger or whatever it was at the time about the new Airbus plane. You'll see why it's difficult to build a building out of that stuff right now. A robot pretty much put all that composite together in a controlled environment.
Where we are seeing a lot of application structurally is in the retrofits of bridges and other concrete structures, with products such as Fibrwrap by Fyfe Co: http://www.fyfeco.com/
This stuff simply gets glued to and wraps around beams and columns. It has the capacity if designed correctly to increase capacity by 40% and is phenomenally cheap compared to what you'd have to do with steel members to increase capacity similarly.
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