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RE: How to Retrofit a Concrete Beam

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The CBC let you to increase vertical load by 5% without reinforcing. You add more than that?

Marius N. Tomutza
MNT DESIGN



--- On Fri, 5/21/10, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:

From: Harold Sprague <spraguehope(--nospam--at)hotmail.com>
Subject: RE: How to Retrofit a Concrete Beam
To: seaint(--nospam--at)seaint.org
Date: Friday, May 21, 2010, 8:39 AM

Jed,
Determining the existing concrete strength and reinforcing is a must.  Depending on the year of construction, you could have ample reserve to carry the load.  There are many ways to tackle the problem.  You need to start out with the fundamentals:
ASCE 11
ACI 437R
ACE 437.1
ACI 228.2
 
Contact Olsen Engineering for assessment needs. 
http://olsonengineering.com/2007site/index.php
 
Once you have assessed the problem, you can tackle how to reinforce it if it requires reinforcment.  There are ACI documents for this as well.  Carbon fiber may be able to help.  Contact Fyfe
http://www.fyfeco.com/
 
You can also construct an upset beam which increases your "d" on your existing reinforcing.  You can add structural steel.  You can post tension it with harped strand.  There are many possibilities. 

Regards, Harold Sprague


 

From: erik_g(--nospam--at)cox.net
To: seaint(--nospam--at)seaint.org
Subject: How to Retrofit a Concrete Beam
Date: Thu, 20 May 2010 22:03:58 -0700

Existing structural plans show "pre-cast concrete beams by others" (which are above grade, not in the soil) running 25 ft O.C. and the dimensions are approximately 24"wi X 36" deep.  These beams run approximately 50 ft to hold up a building on top.  Below is a parking garage underneath the building.  We cannot find the existing plans that show the existing reinforcement  in the concrete beam, so we cannot analyze the existing beam with the new live load.  The reason why we are adding more live load onto the concrete beams is due to an architectural remodel. 
 
I guess I have a few questions.  First, how would someone go about analyzing an existing concrete beam and not knowing the reinforcement.  How can we find out what the reinforcement is?  Can we xray the concrete beam?  Or is there any other procedure to figure this out?
 
Also, i'm assuming the worst and i cannot figure out what reinforcement is doing inside the concrete beam.  Is there a way to retrofit these concrete beams without knowing the existing reinforcement?  How would you retrofit the concrete beams? Please go into detail as much as you can with the procedure.
 
Thank You,
 
STRUCTURES
JED TORCEDO
949.715.0775
 


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