ASCE 7-10 12.3.3.4 and redundancy

[Zman42]

Section 12.3.3.4 says that the design forces determined from Section 12.10.1.1 shall be increased by 25% for the connection of diaphragms to vertical elements. In section 12.10.1.1 diaphragm forces are calculated by equation 12.10-1 and compared to the seismic forces calculated from the structural analysis. If the structural analysis forces govern, you would design your diaphragm using those forces. My question is this: If the structural analysis forces including a redundancy factor govern, does the code require you to multiply your diaphragm connection force by the redundancy factor and the 25% increase? Or is the 25% increase only applied to the force determined in equation 12.10-1?

 

[JAE]

Both ρ and the 25% are additive for the connection of diaphragm to vertical element (i.e a wall or brace line).

The 25% is an up-factor of the source diaphragm force - whether the calculated seismic force or the floor-ceiling diaphragm force.
The calculated seismic force has ρ in it to begin with.

Section 12.10.1.1 does say this:
[blue]"The redundancy factor, ρ, applies to the design of the diaphragms in structures assigned to Seismic Design Category D, E or F. For internal forces calculated in accordance with Eq. 12.10-1, the redundancy factor shall equal 1.0. For transfer forces, the redundancy factor, ρ, shall be the same as that used for the structure. For structures having horizontal or vertical structural irregularities of the types indicated in Section 12.3.3.4, the requirements of that section shall also apply."[/blue]

The term "transfer forces" implies to me the connection force between the diaphragm and a collector or vertical element.

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