🚀 go-pugleaf

Most collapses either are caused by bridge separation from the column and/or
the column crumbling (collapsing)...

In San Francisco the double-decker viaduct collapsed due to the columns on
both sides crumbling and therefore the bridge was separated from the column.

In Los Angeles the two bridges that collapsed at the I-5 / SR-14 interchange
were due to bridge separation.

Also, in Los Angeles, most of the I-10 Santa Monica Frwy viaduct collapse
was due to the colums underneath crumbling.

The two ways engineering has learned is:

1) New columns should be strong enough not to collapse in an earthquake and
existing ones need to be retrofitted with some type of casing (steel) to
prevent collapse during horizontal movement.

2) New bridges are usually one long span with very few joints, and at those
joints the two parts are joined together.  Existing structures should also
be tied together so if one bridge fails, the other will either fail with it
or hold it up.  This prevents people from driving off the edge which is what
happened to a police officer at the I-5 / SR-14 interchange and on the
Oakland Bay Bridge.

Hopefully this has helped you understand some of the things we have learned
from previous collapses.  Next time you see a column cased in steel you will
understand why...

Warren


"Vincent Valencio" <volksdriven63@hotmail.com> wrote in message
news:88e6ca33.0108101737.4377befd@posting.google.com...
> Caltrans never learns.  Those freeways with the T shaped columns
> directly under are dangerous.  Look at how unstable it is.  Just like
> trying to balance a dinning room table on one foot and to expect it to
> stay upright once you set your plate down.
>
>
> David Nebenzahl <nobody@but.us.chickens> wrote in message
news:<3B72C87B.38024F02@but.us.chickens>...
> > "Paul S. Highland" wrote:
> >
> > > Vincent Valencio wrote:
> > >
> > > > What has happened to the double Decker freeway in San Francisco?
You know the
> > > > one that has collapsed in the earthquake. Have they rebuilt it
stronger then before?
> >
> > [...]
> >
> > > I believe all those structures were built in the 1950s with inadequate
> > > bracing.  While construction standards have improved vastly since
then,
> > > many people might still have fears about double-deck structures being
> > > unsafe.
> >
> > I admit that I cringe every time I end up driving on the double-deck
> > portion of the 280 "extension", especially when I'm on the lower
> > (northbound) part. (I cringe a little less driving on the Bay Bridge.)
> >
> > --
> > after the crash, there will be fewer resources, fewer products, less
> > advertising... and fewer designers. there will be no more sumptuous
> > coffee table annuals, no more mass-mailings on creamy paper inviting
> > members to attend gala events in distant cities. phone messages will
> > be left unanswered, email unreturned, websites unsurfed. there will
> > be less paper and more trees, fewer cars and more walkers, less airtime
> > and more air. people will feel less assaulted by images and products
> > and more attentive to the spaces between them. and they will begin to
> > call these undesigned spaces "nature."
> >
> > - Adbusters (www.adbusters.org)