2010 CBC Concrete Provision relating to ACI318 Appendix D

[palves]

Is anybody familiar with CBC provision 1908.1.9. It basically refers to Appendix D.3.3.4 but gives us exceptions when we don't need to follow D.3.3.4. Exception 2 applies when the anchor force is calculated using ASCE7 equation 12.11-1, which applies to Anchorage of Concrete Walls to Flexible Diaphragms.

We're retrofiting a building and my dilemma involves the connection of an existing concrete tilt wall to an existing slab. My co-worker says that I can use this exception, but I say that it doesn't apply since it has to be used with a flexible diaphragm. Since we're connecting our wall to a slab then we don't have a flexible diaphragm and therefore can't use that exception.

Thoughts?

 

[sandman21]

Your co-worker is incorrect if you are not using 12.11-1. The out-of-plane wall anchorage load already applies an increase on the loads, .8/.4 = 2.0, which is similar to the exception to ductile failure by reducing the anchor capacity by .4, 1/.4 = 2.5. So if you need to retrofit a rigid diaphragm and are not using 12.11-1 you need to comply with the ductile requirements.