Story Drift Per ASCE Table 12.12-1

[ampersand]

I find myself in disagreement with a plan checker- go figure.

ASCE Table 12.12-1, first row, specifies allowable story drift for buildings with "interior walls, partitions, ceilings, and exterior wall systems that have been designed to accommodate the story drifts." The last row pertains to "all other structures". So...

What does that clause mean? Exactly which systems are designed to accommodate the story drifts? Do they mean that I would have to design slip-capable connections for these systems? Or do you guys and gals make any assumptions about common systems- for example, are conventional wood-framed wall/ceiling systems assumed to be able to accommodate the story drifts?

Cheers,

 

[DST148]

The drift limits given in NEHRP Recommended Provisions, FEMA 450-1/2003 Edition are similar to ASCE 7 -05. As per the commentary given in FEMA 450-2/2003 Edition - The drift limits for low-rise structures are relaxed somewhat provided the interior walls, partitions, ceilings, and exterior wall systems have been designed to accomodate story drifts. The type of steel building envisioned by the exception to the table would be similar to a prefabricated steel structure with metal skin. When the more liberal drift limits are used, it is recommended that special requirements be provided for the seismic safety elements to accomodate the drift.