We always have held commercial structures to a higher standard unless the
residential structure required full-compliance rather than prescriptive
design. Still, in Southern California, it is very uncommon to find a
commercial structure which is not entirely sheathed (vertically) with OSB or
Plywood. Yet is very common to find a multi-million dollar home with the
minimum shear required to satisfy code. One argument, that does not seem to
hold up, is that builders claim stucco applied to a completely sheathed
building will crack much sooner than one with minimum shear panels in place.
If I recall, APA addressed this issue and I have corrected builders and
architects who believed this to be true.
I think the original argument is based on structural engineering being used
principally to protect buildings occupying large numbers of people and thus
mitigating greater risk in commercial structures.
Still, I am planning on running comparisons on fairly simple prescriptively
designed homes to show that there are calculated uplifts on minimum panels
that prescriptive codes do not require holddowns on. The point is that
prescriptive design does not meet the minimum compliance of engineered homes
and I believe this must be the baseline.
Finally, the argument is that prescriptive built homes have proven to
protect lives - and I don't argue this although members of CUREe made it
clear that there is great concern that prescriptively constructed homes may
not fair as well in a larger earthquake than Northridge (force considered)
and more lives may be lost. Still, the prescriptive argument contends that
homeowners have an unreasonable expectation of performance an that the
damage to prescriptively built homes during Northridge Earthquake was
artificially high by a demand driven market and should not have been
considered unreasonable in light of the life-safety concern.
My opinion - those who are most affected financially are those who can least
afford to pay the repair cost since prescriptive homes in high risk areas
are predominately created for low and lower-middle income families.
With the Aas decision, this should create incentive for prescriptively built
homes in the middle and upper-middle class incomes as well.
I guess we can all expect a lot of work after then next large shaker!
> -----Original Message-----
> From: Dan Goodrich [mailto:dang(--nospam--at)karren.com]
> Sent: Wednesday, April 04, 2001 9:19 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Aase ruling
> This brings up an interesting point. There is a perception
> out there that commercial projects should be built to a
> higher standard than residential. Shouldn't they be the
> same? I've designed homes that are significantly larger
> than some of the commercial projects I've worked on.
> I realize that there will be differences based on
> occupancy and other related matters.
> Are we as an engineering community holding commercial
> jobs to a higher standard than homes? One example I
> can think of would be the amount of reinforcing required
> in foundation walls.
> Dan Goodrich, P.E.
> ----- Original Message -----
> From: "Neil Moore" <nmoore(--nospam--at)innercite.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Tuesday, April 03, 2001 8:33 PM
> Subject: RE: Aase ruling
> > Jason and Dennis:
> > On the other hand, I had a take-over project with 46 townhouses. 23
> > uphill and 23 downhill, basically two plans, each alike. The
> > framing and exterior stucco completed. Although every one of the plans
> > were the same, it appeared to be a different crew on each one.
> > Took us three years to complete the project, including putting a
> > designer on the site to straightened out all of the glitches. The
> > superintendent, who was from a central California mountain
> area, accussed
> > us of "commercially" engineering the buildings. Of course the
> project was
> > a 1000 feet from the San Andreas fault and was on a high bluff
> facing the
> > ocean.
> > The sherriff came in one day and took him off the project. This was
> > sometime after he had threatened one of my engineers.
> > Neil Moore, S.E.
> > neil moore and associates