Seismic Retrofit of Historic Building

Seismic Retrofit of Historic Building

Postby AREND » Sat Nov 08, 2014 11:39 am

What is the most cost effective and safest material for Seismically Retrofitting a Historic house that is being converted into a Library?

1- wood
2- steel
3- concrete
4- reinforced concrete

my answer is 2, but Chen says 1. The common (and probably only viable) product for a wood based seismic system is a Shear Wall. That means the removal of the face of a wall and treating it with plywood, hold-downs, posts, etc. which needs to be accomplished in a distributed fashion around the building. This is the most intrusive method for a historic building and in my opinion will be unacceptable?

What do you think?
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Re: Seismic Retrofit of Historic Building

Postby clutjen » Sun Nov 09, 2014 10:18 am

The two historic preservation firms I have worked for over the past six years have primarily used the wood shear wall approach for seismic retrofit. It is the most cost-effective approach. It can be more intrusive labor-wise, but overall less-intrusive visually when the project is complete. Of course, in buildings with pristine detailed plaster interiors the challenge is more difficult and may demand a different approach. The architect and structural engineer can work together strategically to choose locations for the shear walls that will limit removal of interior finishes. Typically the project will involve structurally rated plywood at the roof, shear walls that transfer load to the foundation, horizontal diaphragms, and tie-downs at the roof eave and foundation.

Chris
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Re: Seismic Retrofit of Historic Building

Postby AREND » Sun Nov 09, 2014 1:14 pm

clutjen wrote:The two historic preservation firms I have worked for over the past six years have primarily used the wood shear wall approach for seismic retrofit. It is the most cost-effective approach. It can be more intrusive labor-wise, but overall less-intrusive visually when the project is complete. Of course, in buildings with pristine detailed plaster interiors the challenge is more difficult and may demand a different approach. The architect and structural engineer can work together strategically to choose locations for the shear walls that will limit removal of interior finishes. Typically the project will involve structurally rated plywood at the roof, shear walls that transfer load to the foundation, horizontal diaphragms, and tie-downs at the roof eave and foundation.

Chris


Thanks for the reply. Its good to hear it from someone who has experience in the field. I guess, as you mentioned it depends on the interior intricacy of the building. I don't know how we can assume this, with the limited knowledge given. Based on your experience in historic preservation, is there a formula (for instance, based on occupancy or construction type, xyz method should be used) or is this a blanket approach for all wood frame construction? Is the wood shear-wall approach viable for taller than two story buildings?
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Re: Seismic Retrofit of Historic Building

Postby clutjen » Mon Nov 10, 2014 10:27 pm

Unfortunately, there is not a standard or simple formula for determining the best strategy for seismic upgrade. I guess that is one of the things though that makes architects and structural engineers valuable. The most economical way to seismically upgrade a wood-framed building will almost always be wood shear walls and tie-downs. And this strategy can be used in multi-story buildings. The shear loads must have a continuous path from the top to the bottom of the building. A good structural engineer will be able to pick out limited locations of employing shear walls in both directions hopefully without a major impact on the building footprint. Steel braces and moment frames are more typically used in URM, unreinforced masonry buildings. Core-drilling is another newer technique that is gaining popularity in masonry buildings.

Chris
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Re: Seismic Retrofit of Historic Building

Postby hnQ_9999 » Wed Mar 08, 2017 3:09 pm

Interesting discussion.
A Historic House, can as well be erected 50 years ago, per OHP's 50 year threshold.
So it can be steel, masonry or wood originally. Without knowing what it was constructed for,
how complex nor simple in plan or section, I will have to go with common sense, which is
wood construction for a "House".
And that is the only reason I pick (a). The rests are conditional because we have known
nothing about its plan or structure.
Anyone ?
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Re: Seismic Retrofit of Historic Building

Postby Coach » Wed Mar 08, 2017 4:22 pm

What if the primary walls are masonry?

Dumb question IMO.

My first inclination would be steel because you can accomplish more with less.

What I do know for sure is this question cam out of a warped mind.
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