Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Housing Performance Objectives

[Subject Prev][Subject Next][Thread Prev][Thread Next]
In a message dated 97-12-09 08:54:39 EST, Ron Hamburger write:

>Under the International Building Code, any Owner/Design team may 
>elect to design for a higher SDC than specified by the Code.  
>Interstingly, these SDCs are labeled A, B, C, D, E, and F (A being 
>the lowest and F the highest).

Buildings with a SDC above 'A' are likely to be significant structures that
have well-defined lateral systems that are amenable to extensive analyses and
design, and project budgets that can support the extra work and quality
assurance that are required.  This generally isn't the case for houses, and
most of them likely will be in Category A..

>I am afraid that building officials, despite their fears, will be 
>stuck verifying designs to other than life safety.  However, they 
>need not fear litigation any more than they currently do.  If their 
i>s a code available for these designs, they need only verify (as 
>would the reasonable building official) that the design and 
>construction meets the code - nothing more or less.  Similarly, 
>engineers need only demonstrate the same. - not that the building 
>actually performs as the code suggests.

At the risk of oversimplifying things, the codes now have one stated objective
for seismic performance: life safety.   Design to these provisions, and the
building shouldn't cause casualties from failures in the gravity and lateral
force systems.  And a test for whether a building has performed adequately in
an earthquake can be answered fairly straightforwardly by looking at the
number and nature of the casualties.  When multiple levels of performance are
defined based on damage and functional goals, unsatisfactory performance will
generate many more opportunities for arguments over the relative contributions
by the codes, engineers, inspectors and contractors.  Was the damage due to
the code's inadequate predictive abilities, the engineer's inadequate analyses
or competence, the contractor's careless or uninformed workmanship, or the
inspector's oversight or acceptance of an as-built condition that upon
analysis meets the 'A' standard, but not the standard of record?  

The good news is that the public will readily understand the SDC concept.  The
bad news is that there will be significant differences of interpretations and
expectations over what damages are reasonable and performance 'guaranteed' for
the different categories.  I'll bet three cups of coffee to one that owners
and their attorneys will have different takes than those who designed, built
and inspected their earthquake-damaged buildings.  Ron Hamburger has more
faith than I do that if you have the facts and code compliance on your side,
you will prevail.  We're all aware of cases where business and monetary
factors drove the outcome in another direction.  Having worked with many city
attorneys and county counsels, I can confidently predict that these folks will
have major heartburn over *enforcing* or *certifying*  categories above 'A'.
When it comes to such legal concerns, building officials have little say
because no code adoption ordinance will reach the council or board unless it
has been written or approved by the attorneys.

Franklin Lew, SE
Orinda, CA