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Re: Seismic Upgrade prob. W/97 UBC

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Lynn, I agree with you entirely. One of the things we can do with your help 
is to attack the code through SEAOC which may not solve your immediate 
problem but would be a start.
The building official (in his infinite wisdom) is not thinking through these 
code changes and will never question the written code. His liability is 
questionable but yours is a sure thing as long as you deviate from what is 
published.
You and others have to get SEAOC to issue a position statement on this 
section of code to show the building official (and to protect your liability) 
that there is a large percentage of our professional community who disagree 
with this approach and that it is not in the best interested of the owner. 
In my area, the engineer is only required to bring the addition up to current 
code and not the rest of the structure unless significantly deficient to the 
code it was originally designed for.
Your building official appears to be stuck on the letter of the code rather 
than interpretation and significance of it. 
I would suggest that any engineer who understands who detrimental these 
changes are, not mater where in the world you live, should send a letter or 
email to SEAoSC (seaosc(--nospam--at)aol.com) and SEAOC (seaoc(--nospam--at)aol.com) and ask that they 
review the comments regarding this section of the code and issue a position 
statement recommending that the requirment for rigid diaphragm analysis be 
placed on hold until the results of the Curee-CalTech project and other 
relevant information about the cause of damage in Earthquakes and Hurricanes 
is properly evaluated by the engineering community to pinpoint the cause of 
failures.

Unless you can get SEA behind you (and the rest of us on this issue) your 
liability will be in jepordy even if the local building offical allows you to 
use your own judgment as to the relevance of the retrofit work.

Just a simple statement from a lot of engineers will help.

Dennis Wish PE

PS:  The retrofit of URM buildings still consider floor diaphragms made up of 
straight over diagonal sheathing to be flexible. Not exactly in compliance 
with the consideration of plywood diaphragms. At a capacity of 500 to 600 
plf, it sure calc's out as stiff or stiffer than plywood. How come we aren't 
considering URM retrofits with rigid diaphragm analysis?