I know that C[sub]d[/sub] is used to factor up the "elastic" lateral story drifts to provide a more realistic lateral drift under a seismic event. The IBC indicates the use of C[sub]d[/sub] with [δ][sub]xe[/sub] in section 12.8.6 of the ASCE 7.
However, there is also a vertical component to seismic effects required using 0.2S[sub]DS[/sub] to be added to the dead loads of a member.
The question is raised as to whether the C[sub]d[/sub] factor can be or should be applied to this vertical seismic load to get a more accurate measure of vertical deflection under dead and seismic loads.
I can't think of a significant reason to be concerned with vertical DL deflection plus vertical magnified seismic deflection except under some cases where a vertical sag might be a concern for clearances etc.
Also, ASCE 7 only speaks of C[sub]d[/sub] in the context of story drifts, not vertical beam deflections.
So the question is - do we ever include the C[sub]d[/sub] factor on the 0.2S[sub]DS[/sub]?
However, there is also a vertical component to seismic effects required using 0.2S[sub]DS[/sub] to be added to the dead loads of a member.
The question is raised as to whether the C[sub]d[/sub] factor can be or should be applied to this vertical seismic load to get a more accurate measure of vertical deflection under dead and seismic loads.
I can't think of a significant reason to be concerned with vertical DL deflection plus vertical magnified seismic deflection except under some cases where a vertical sag might be a concern for clearances etc.
Also, ASCE 7 only speaks of C[sub]d[/sub] in the context of story drifts, not vertical beam deflections.
So the question is - do we ever include the C[sub]d[/sub] factor on the 0.2S[sub]DS[/sub]?