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RE: Reinforcing Existing Beam[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Reinforcing Existing Beam
- From: Harold Sprague <harold.sprague(--nospam--at)neenan.com>
- Date: Tue, 16 Mar 1999 16:38:50 -0700
You might want to consider jacking from the new low beam. This will preload the new beam and reduce the initial stress on the existing beam. You will also have to calculate the horizontal shear to size the WT connectors and the welds. 1. Install the low beam 2. Apply a load using a hydraulic jack and load cell 3. Weld a pair of WT's in the space to lock the preload and provide composite action. Regards, Harold Sprague The Neenan Company -----Original Message----- From: Rehan.Nawab(--nospam--at)fluordaniel.com [mailto:Rehan.Nawab(--nospam--at)fluordaniel.com] Sent: Saturday, March 13, 1999 7:57 AM To: seaint(--nospam--at)seaint.org; Rehan.Nawab(--nospam--at)fluordaniel.com; structx(--nospam--at)mlists.net Subject: Reinforcing Existing Beam Folks, I am in a situation, where I have to reinforce an existing beam (18B40) while it is still carrying load. The client requirement does not allow for welding cover plates. Therefore, I am opting to add a new WF beam to the existing beam using 3/4" A325 bolts. This existing beam has full lateral support, i.e. Fb = 24 ksi. This existing beam under existing loads is stressed to 18 ksi. This only allows for approximately 6 ksi (18+6=24 ksi) after adding the new beam. Since, the new loads are heavy, this requires a very large composite section modulus to keep the stress around 6 ksi. In, this case W33x201 attached to 18B40. Is this approach overly conservative? Is there any other way you would analyze the problem? Existing beam is up-high and I don't think, I can have the beam jacked-up to unload the existing stress in the beam. Existing Moment = 100 ft-kip Combined Existing and New Moment = 385 ft-kip Composite Section Design Moment = 285 ft-kip Composite Section Modulus = 611 in3 Any ideas? Thanks in advance. Rehan Nawab, P.E. P.S. I posted this question yesterday, but it appears it got missed some how.
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