Friday, February 20, 2009

Re: ASCE 7-05: RSA Procedure per 12.9

> Your confusion is understandable after looking through the RISA
> implementation of the RSA.  I'm familiar with the ETABS approach,
> which is much more straightforward.

That's good to know. I thought it was just me.

> To combine the X and Y directions, you can use the SRSS method (the Z > direction is independent).  Your base shear for the RSA would then be
> 7.247 kips in the X-direction.

Grrreat. I think that's what I did. I think.

> The response reduction factor R and the importance factor I should be
> used, so this number can be multiplied by I/R.  The result should be
> compared to the equivalent lateral force base shear and only
> increased if it is below 85% of that value -- you cannot scale it
> down.

Check.

> RISA offers a spreadsheet for calculating the scale factors.

Okay, I didn't notice this! I have the newest version of RISA-3D, and I have noticed the documentation seems a bit "behind the times." If you hadn't pointed this out I would never have figured it out myself!

Thanks!

More later, I'm sure. Hope this is helpful to others listening in.

******* ****** ******* ******** ******* ******* ******* ***
* Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
* This email was sent to you via Structural Engineers
* Association of Southern California (SEAOSC) server. To
* subscribe (no fee) or UnSubscribe, please go to:
*
* http://www.seaint.org/sealist1.asp
*
* Questions to seaint-ad@seaint.org. Remember, any email you
* send to the list is public domain and may be re-posted
* without your permission. Make sure you visit our web
* site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********