In another of Mark Bassett's fine editorials from Ely, Nevada (this guy is a master at PR), I note that the Nevada Northern machine shop needs seismic retrofit. Any idea of what this would entail? Thus far, the only seismic stabilization I've seen on a railroad building was the former State Belt roundhouse in San Francisco, which developers are attempting to rent for offices. The designers simply added crude A-frames out of big pipe inside the walls. Any ideas of how such protection might be added to such a historic building less intrusively?

ryarger@rypn.org

The best method is probably one called isolation bases. Thet're big rubber pads that fit between a building and its foundation. Trouble is they'd be a bugger of an expense to retrofit, as you'd have to jack the building up off its foundation and do a good bit of work on the foundation and the bulding both to mechanically integrate them. (The local art museum is looking at doing just that to a truly gruesome figure.) I'm affraid that if one want to do this properly, it's something you'd have to go to a stuctural engineering firm for. The A-frames might actually be the best option for a medium sized masonary structure. Maybe a century from now they'll be romantic like the truss rods in many cathedrals to keep the piers from spreading, or the earthquake bolts in old houses. (Usually visible externally as iron S or star shaped iron fittings at strategic places on masonary walls.)

Sincerely,
David Ackerman

david_ackerman@yahoo.com

> The best method is probably one called
> isolation bases. Thet're big rubber pads
> that fit between a building and its
> foundation. Trouble is they'd be a bugger of
> an expense to retrofit, as you'd have to
> jack the building up off its foundation and
> do a good bit of work on the foundation and
> the bulding both to mechanically integrate
> them. (The local art museum is looking at
> doing just that to a truly gruesome figure.)
> I'm affraid that if one want to do this
> properly, it's something you'd have to go to
> a stuctural engineering firm for. The
> A-frames might actually be the best option
> for a medium sized masonary structure. Maybe
> a century from now they'll be romantic like
> the truss rods in many cathedrals to keep
> the piers from spreading, or the earthquake
> bolts in old houses. (Usually visible
> externally as iron S or star shaped iron
> fittings at strategic places on masonary
> walls.)

> Sincerely,
> David Ackerman

I'm no expert at all on buildings or engineering. But considering the building at hand (I'm assuming that Bob was talking about the Machine Shop AND the enginehouse, they are connected), I'd say the method with the A-frame is probably the best to go. The machine-shop on the outside was built with sandstone that is natural to the area, the inside walls are of cinderblock construction. The engine house is of cinder-block construction in and out. The machine shop was built around 1939-41. The engine house was in 1943-44.

In many ways, seismic retrofit is like restoring a vintage passenger car for daily public operation. The challenges and compromises are the same.

The goal is to bring a deteriorated, potentially unsafe (by contemporary standards) but valuable (culturally or otherwise) structure into compliance with modern construction standards for (as a minimum) basic life safety. The "art" of this science lies in fulfilling the above goal while minimizing disturbance of the historic "fabric" of the structure, and doing so for an acceptable price.

Retrofit strategies are as varied as the structures they are applied to, and can range in scope from simple, discreet fixes of localized defects to instances where one has to almost "destroy the village in order to save it". From my experience (I've engineered a couple of retrofits in Los Angeles), economy and the ultimate use of the structure tend to dictate the project direction, or if the project is to be undertaken at all. If it is desirable to see less of the retrofit hardware in the finished project, that's typically going to cost a lot more.

The scope of structural work on a retrofit can include bracing and strengthening of parapets, towers or other appendages, strengthening or replacement of roof and floor sheathing, upgrading the anchorage of walls to roofs and floors and introduction of new collector/strut elements within roof and floor systems, anchorage of wall veneers, adding redundancy to framing systems which may be susceptible to failure, bracing of tall or slender walls for out-of-plane failure, testing or reinforcing existing shear walls and/or developing new lines of shear resistance within the structure, upgrade or repair of existing foundations or introduction of base isolation or damping systems, analysis of the supporting soil structure, and on and on and.....anybody still awake out there??

Also, one has to consider required improvements to exiting, fire safety, communication, utilities, and many other issues, as well as the aesthetic and economic ones.

Phew. Hope that helps a little.

-Dan-

As a licensed building contractor I have been involved in seismic retrofit. the largest project was a 4 story unreinforced brick building. Basically you are at the mercy of the local building department as they will have the local codes and methods that you must work from. Each city will be a little different however all the methods are basically the same. Dan Es post was right on, I also know Dan E, he is a very good structural engineer.

Upon rereading my own post I realize that I didn't make my most important point clear. A job of any scale at all will really require the opinnion of an experienced licensed structural engineer, (possibly someone like Dan E,) as the job is exceedingly complex, and, BobK raises a very important point here, not just on the structural/mechanical level. I really meant that this was not a do it yourself kind of thing, like strapping the hot water heater to the floor joists. Anyway, sorry about my lack of clarity. Sometimes I ought to just keep my mouth shut, but I enjoy too many things. Sorry.

Sincerely,
David Ackerman

david_ackerman@yahoo.com