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RE: Location of footing reinforcement[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Location of footing reinforcement
- From: HECTOR MORERA <HMORERA(--nospam--at)GoodKindInc.com>
- Date: Tue, 15 Sep 1998 11:18:57 -0400
ok here's the first taker ... i really don't have this problem because i mainly work on bridges and we just put in a double mat in a 4'-6' thick footing but i'd like to think that the wall which is tied into the footing acts somewhat compositely with the footing creating an inverted t-beam. yes, i know the reinforcement isn't designed for the horizontal shear at the joint but the wall usually is so massive with respect to the footing that it will restrain the top of the footing from going into tension. hector -----Original Message----- From: rlewis(--nospam--at)techteam.org [mailto:rlewis(--nospam--at)techteam.org] Sent: Tuesday, September 15, 1998 10:03 AM To: seaint(--nospam--at)seaint.org Subject: Location of footing reinforcement Let me ask an engineering judgement question which I hope sparks a lot of controversy and causes many different opinions to be brought forth. A week or so back someone had posted a question regarding minimum thickness of a concrete footing. It reminded my of a engineering philosophy question of where to locate the longitudinal reinforcing in a continuous strip footing. I think traditionally we locate longitudinal reinforcing in a strip footing at the bottom. My question is WHY? What is the purpose of longitudinal reinforcing? Is it to: -span across local settlement of the soil? -tie the wall footing together to prevent it from pulling apart, somewhat similar to a bond beam at the top of a wall? -somehow provide strength to the footing element? Why does it have to be at the bottom to provide these functions? Wouldn't it make more sense to put it at the top? For strength, a larger load can be supported over a slight settlement using negative moment at ends then a positive moment at the middle. It would be easier to place the reinforcing and not worry about bottom cover if the contractor were able to pour the concrete to say 2 inches from the top of footing, lay the reinforcing in place and then pour the rest of the concrete. What difference does it make if the reinforcing is top or bottom in regards to shrinkage? I look forward to reading many different opinions on this topic. __________________________________________________ Richard Lewis, P.E. Missionary TECH Team rlewis(--nospam--at)techteam.org The service mission like-minded Christian organizations may turn to for technical assistance and know-how.
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