Commins AutoTight® Rod Holdown System

Specifying the AutoTight® Components:

1. Rod diameter will determine which AT Take-Up device will be used. (ICC Tables 1a or UBC Table 2a can be used). The AT 75 fits up to ¾” rod, the AT 100 fits up to 1” and the AT 125 fits up to 1-1/4” rod. Verify that the AT compression capacity is not exceeded.

2. In runs 4A and 5A some of the levels have been combined by extending the larger rod to the floor above. This is done when a take-up device is not required at every level (per the structural plans.)

3. A bearing plate is required with each take-up device. Bearing plates are selected based on the required loads at each floor. Example: Run 4A level 2 requires 9,500 lbs. Select an S10 plate with 10,156 lbs capacity in DF-L. (See ICC Table 1a).

4. The table is self-explanatory. Consult factory for special conditions
 

5. The threaded rod length is determined by the story height and the height of the termination header at the top level.

6. Trimmers (Compression Studs) are determined by the differential loading on a floor by floor level. Some framers prefer a single trimmer while others prefer laminated trimmers (a 4 x 6 vs. 2 ea 2 x 6’s). Optional combinations can often be used depending on framer preferences.

7. The embedded anchor rod is normally the same as the level 1 threaded rod. The embedment plate and depth are determined by using the embedment table along with the concrete strength. Hint: It may be more cost effective to specify only one or two embedment diameters. This makes placement much easier for the contractor. Reducer couplers transition the rod to the required size.
 

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