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RE: Topping required on precast plank?

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I would be careful about having the top of beams flush with the top of the plank because these beams usually need to be fire rated and for a two hour rating I believe you need a minimum of 1 1/2" of concrete cover.  This means that you would have to drop the top of your beams 1 1/2", fill the void with concrete and then apply the levelling compound over this.
 

Albert J. Meyer, Jr., P.E.
Senior Project Engineer
Cagley, Harman and Associates
Structural Engineers / Parking Consultants
1015 West Ninth Avenue
King of Prussia PA 19406-1222
ameyer(--nospam--at)cagleyharman.com
(610) 337-3360
(610) 337-3359 Fax
www.cagleyharman.com

-----Original Message-----
From: Terry Triest [mailto:tatriest(--nospam--at)hayeslarge.com]
Sent: Thursday, May 01, 2003 11:30 AM
To: Seaint
Subject: Topping required on precast plank?

Our client is requesting to use a self-leveling material to essentially compensate for the incidental cambering of the plank.  They want to recover most of the 2" which would be lost with the standard 2" topping.
 
Mostly, the plank is supported by bearing walls (5 levels), but the central lobby is at the knuckle of the angled wings and is steel framed.   My concern arise because the supporting HSS beams might need to be flush with the top of plank because of the 10' floor to floor height.  This imposes a crack concern on either side of the beam.
 
Concern # 1 - I feel the self-leveling material is inadequate for crack control at the beams.
 
Concern # 2 - Can we use 1" of ARDEX K-15 with some assurance that cracking can be controlled?
 
Concern # 3 - Has anyone had problems with the topping adhering to the top flange of the beam in this framing condition? 
 

Terry Triest, EIT
Structural Department
P: 814-940-4041
F: 814-949-2644