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#67763 - 11/24/16 10:19 PM Wind & Seismic forces using ASCE 7-10
Mak Offline

Registered: 12/12/08
Posts: 82
Loc: india
Dear all,

ASCE 7-10 code has a reduction factor of 0.6 on wind loads and 0.7 on seismic loads. These factors are given in ASCE 7-10 clause 2.4.1 for load combinations.
Based on this when we perform analysis in PVElite using ASCE 7-10, foundation loads which we get in output summary are not 100% wind and seismic.
This means that for design of foundation we have to again divide these loads by 0.6 for wind & 0.7 for seismic?
Also, the same clause of ASCE indicates do not use allowable stress increase. How it is taken care?

Edited by Mak (11/24/16 10:21 PM)
Makrand Sakpal
Contact No: - 9967949656

#68068 - 01/07/17 12:27 PM Re: Wind & Seismic forces using ASCE 7-10 [Re: Mak]
mariog Offline

Registered: 09/29/07
Posts: 653
Loc: Romania

I guess that nobody answered your question because it is too much to explain on elementary side.
ASCE 7-10 has two basic combinations sets, one is under title 2.3 COMBINING FACTORED LOADS USING STRENGTH DESIGN, other is under title 2.4 COMBINING NOMINAL LOADS USING ALLOWABLE STRESS DESIGN. Giving the information to a Civil Specialist and saying that the combinations are ASD will solve the problem or shall complicate it, however it is the start you need.

About factors 0.7 and 0.6, a quick google search with "why 0.6 wind in ASCE 7" comes up with a lot info, as for example the file attached. Similarly for seismic. Here, in case you work with non-American maps/data, you must pay attention what primary data you have input in your calculation as the approach to make sense.

About the last question, what ASCE 7-10 says for ASD is self explanatory and frankly, I'm not able to explain it better; it is worth to note is specific for structures under ASCE 7 requirements "Increases in allowable stress shall not be used with the loads or load combinations given in this standard unless it can be demonstrated that such an increase is justified by structural behavior caused by rate or duration of load."

Why-0.6.pdf (235 downloads)

#69834 - 08/28/17 01:14 AM Re: Wind & Seismic forces using ASCE 7-10 [Re: mariog]
LINUS Offline

Registered: 04/07/08
Posts: 21
Check out new presentation on Wind and Seismic Forces - Treatment by various codes at www.linuserve.com

#72139 - 09/06/18 06:03 AM Re: Wind & Seismic forces using ASCE 7-10 [Re: Mak]
Mak Offline

Registered: 12/12/08
Posts: 82
Loc: india

In PVElite 2018, I noticed that even I change the wind/seismic global scalar factors (ASCE7-10) to 1 instead of 0.6/0.7 there is no change in output summary for wind and seismic forces and moments! Please clarify.

Also, what is scaled maximum moment on basering?


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