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Strategies & Market Trends : The Residential Real Estate Crash Index -- Ignore unavailable to you. Want to Upgrade?

To: arun gera who wrote (229287)	11/18/2009 9:25:11 AM
From: alanrs	Respond to of 306849

Okay, not being an engineer and not being able to draw pictures here I'll try to go through a sequence of events that sound plausible to me. Plane hits wiping out half of the columns on one side going in. No problem yet. Fire causes floor beams to expand, getting longer, force applied sideways against exterior columns (no problem, columns apply force back as they are flexed) and sideways against the concrete core (potentially big problem) causing cracks in the core. Fire continues causing trapped water in the core to vaporize and pieces of some undetermined size to 'pop', reducing the thickness of the concrete covering the rebar. Fire continues, further heating the rebar reducing its strength. Floor beam(s) fail and as one end falls the force on that end is down and toward the core in an arc. The force at the core is up and away from the core, also in an arc, welds do not fail and the embed with the studs in the already cracked concrete is where that force is applied to the core. Sections of the core, still attached to the embeds are pulled out and the core fails. Now there's shock load and shear and the whole thing drops, bolts, weld, the whole thing fails. ARS Sorry it took a while to respond, had to take grandson to school and walk the dog.