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Politics : Bush-The Mastermind behind 9/11? -- Ignore unavailable to you. Want to Upgrade?

To: sea_urchin who wrote (9160)	12/7/2004 10:02:17 AM
From: Raymond Duray	Respond to of 20039

Searle, Re: impression that concrete was always used because of its superior compressive strength. You had me scratching my head for a while. Steel is generally always rated in yield strength, also known as tensile strength. For three decades, I haven't known the relation of steel's tensile strength to its compressive strength. According to one professor's notes on the Internet, the tensile and compressive strengths of steel are roughly equal. newton.dep.anl.gov Most information on structural steel is not available for free on the Internet, so I'm going to pass along this item on tool steel: timken.com Timken says that Ultimate Compressive Strength of Tool Steel is 130% of Ultimate Yield Strength. So that sort of sets the boundaries. What this means in plain English is that the ASTM A36 structural steel used in the construction of the WTC towers had a compressive strength of somewhere between 36,000 and 46,800 pounds per square inch. Or about 10 to 12 times the compressive strength of normal concrete. As a bit of trivial, I read in Engineering News-Record a few years ago about a high rise project in Seattle, Washington which had a unique structural design. High strength steel tubes were filled with ultra-high compression concrete. This material had a yield strength of 20,000 PSI, an extraordinary value. It was achieve by using very high value aggregates including granite and pozzolans (fly ash) to achieve an very dense matrix. Here's some info on pozzolans, also know as silica fume: norchem.com