ASCE 7-10 Non-Structural CH 13 Table 13.5-1
ASCE 7-10 Non-Structural CH 13 Table 13.5-1
(OP)
The third printing of the ASCE 7-10 table 13.5-1 has included overstrength factors Ωo for Architectural Components. Footnote C states "overstrength as required for anchorage to concrete. See section 12.4.3 for inclusion of overstrength factor in seismic load effect."
Here's my question:
Do we use and overstrength factor when we are attaching to concrete?
Does we need to apply this factor if we are using a post installed anchor or cast in place or both?
Are there any exemptions to work around this?
Calculations show that in most cases where you are anchoring a narrow light storage shelf you would need to thru-bolt thru the existing conc. slab (upper level) and into an steel angle to work around this issue. Since your connection is steel then you do not need to apply the overstrength.
Any info or tips would help, thanks,
Here's my question:
Do we use and overstrength factor when we are attaching to concrete?
Does we need to apply this factor if we are using a post installed anchor or cast in place or both?
Are there any exemptions to work around this?
Calculations show that in most cases where you are anchoring a narrow light storage shelf you would need to thru-bolt thru the existing conc. slab (upper level) and into an steel angle to work around this issue. Since your connection is steel then you do not need to apply the overstrength.
Any info or tips would help, thanks,





RE: ASCE 7-10 Non-Structural CH 13 Table 13.5-1
You need to include them for both post-installed or cast-in place anchors where applicable.
The requirements for when it is required and exceptions for its use are shown in ACI 318 D3.3.4.2, D3.3.4.3, D.3.5.2, and D.3.3.5.3.
You would not need it (in my opinion at least) with the a through-bolt to a steel angle as you are no longer within the requirements of Appendix D.
RE: ASCE 7-10 Non-Structural CH 13 Table 13.5-1
However, if the project is in California, the 2013 CBC references ASCE 7-10 with Supplement 1 and 2 (even though, there is no Supplement 2).
Ironically, ASCE 7-10 still says "the overstrength factor, Ω0, does not apply" in section 13.3.1. I am still wondering why the overstrength factor was added to chapter 13 and why it only applies to concrete anchors and why it is always 2.5 when Rp is between 2.5 and 12.
RE: ASCE 7-10 Non-Structural CH 13 Table 13.5-1
510engineer's point is the overstrength factor increases the forces so much that concrete anchors will not work and through bolting will be required.
RE: ASCE 7-10 Non-Structural CH 13 Table 13.5-1
Personally, I think it is overkill and I agree it makes it extremely difficult to anchor with shallow embedments and close edge distances.
The 2006 IBC required the 0.4 brittle reduction factor for equipment (although I believe the oshpd section for CBC did not). The 2009 IBC didn't require it for equipment. Now the 2012 IBC requires it again. Its unfortunate and quite confusing that it keeps changing.