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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 (229278)	11/18/2009 8:02:38 AM
From: alanrs	Read Replies (1) \| Respond to of 306849

"So are you saying, that the core can take 50+ floors of weight and not crack for 30 years and it cannot take the shock of a vibrating beam that is shearing off with the weight of 1-5 floors of rubble from above floors any time?" No, that's not what I'm saying. I don't know the weakest point, the weld is stronger than the beam steel, generally. The application of heat would be a major factor in where the beams failed. What I am saying is that if the beams failed in the middle, or at the exterior columns, but not at the concrete core, that drop would put a sideways force on the core. I know the core is reinforced with substantial rebar, but I've never seen the actual core be fireproofed and I sure have seen what happens if you apply an acetylene torch to concrete. I can see heat causing significant popping and cracking of the core as water boils out and then serious sideways force being applied to that core. I worked at McCormack place years ago and we put up some precast fire escapes way over on the west side while the building was going up starting on the east side. Hundreds of yards away. Eventually they built the building over the train tracks and tied into the fire escapes. Someone miscalculated the expansion joints and we ended up back there because the beams had expanded and poked thru the precast, and not just by a little. Concrete is strong in compression, but weak in tension. ARS