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Re: ASCE 31-03 part 2

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Beer is good...

I would either make the LFRS a bearing/shear wall structure, or a frame system.  That is, either completely connect the walls to the frame elements and assume a lower modulus, E, or de-couple the wall from the frame beams and columns.  In that case, the wall would solely add seismic/dead weight, but you would not rely on the wall panels to resist lateral loads.

As for modeling the combined system, I'm afraid I can't help you with that...  but thanks for the beer.  gettign thirsty after all the CA I am currently handling...  but, I'm not complaining...  :-D

Hope this helps.

On Thu, Sep 17, 2009 at 1:38 PM, Michelle Motchos <mmotchos(--nospam--at)> wrote:
I know I must not have properly included the magic word since I did not get a single response the first time so I'll make sure to include it in this follow up:
For a C3 building would you typically consider removing the URM as decreasing the overall lateral capacity of the building or improving the frame's performance?

From: Michelle Motchos [mailto:mmotchos(--nospam--at)]
Sent: Tuesday, September 15, 2009 3:03 PM
To: seaint(--nospam--at)
Subject: ASCE 31-03

A potential upcoming project will require evaluation be ASCE 31-03 at both the Tier 1 and Tier 2 levels. A quick glance of the plans and it would be a "C3" concrete frame with unreinforced masonry and rigid diaphragms. There are irregularities that I believe will require the application of the Linear Dynamic Procedure during the Tier 2.  Does anyone know of a good reference for how to model and analyze this system for the evaluation? ASCE indicates they behave as a shear wall thru the development of compression struts in the wall for a period until the wall is destroyed and then it transitions to frame frame behavior but I am not sure how to capture this behavior numerically or in a 3d model for the dynamic analysis.

David Topete, SE