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Re: IRC Braced Panels

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Subject: Re: IRC Braced Panels

Ted Ryan wrote:

Again, missing the point.

Respectfully, Ted, I think you are missing the point, 3 of them!

Regardless of whether the IRC calc's out or not,
homes built in a manner consistent with the IRC generally perform well in
high seismic or wind events.

OK, Dennis shot this one down for me already, so I don't need to elaborate. I would be interested in hearing from some of the list members in Florida who have surveyed the damage of the recent hurricanes, to see how well the prescriptive structures performed.

The IRC takes into account the redundancies
that we aren't able to in design.

Why are we not able to account for these redundancies? Why do we neglect them in our designs and then tack on a very large safety factor? The IRC and field observation are telling us that we are designing very conservatively when using the IBC. The key question is, at what point do we strike the balance between an economical design, and a socially acceptable factor of safety? The writers of the IBC are striking the balance for high occupancy and high rise public buildings. The writers of the IRC are striking the balance for single family residences. As long as the goals are different, the results will be inconsistent.

The applicability of the IRC is fairly
restricted so that it isn't used in situations where an engineered design is

I want to work on the planet the you live on! As I noted in my previous post, the IRC is very often allowed "in situations where an engineered design is warranted". Just look at from the political point of view. Home builders provide jobs, tax revenues, homes for families, and an increased tax base to communities. They are well organized, have a strong lobby, and deep pockets for plenty of lawyers. (I wish I could say those things about the engineering community!) I don't think anyone would disagree that IRC designs are less expensive to build, thus increasing the builders profits, and providing lower cost housing to the community. When the builders come to talk to the small community building officials, they carry a big carrot and a big stick. Is there any wonder that only the most obvious violations are flagged as not meeting IRC. As engineers, and as the only group who really understands the safety and performance implications of the codes, it is up to us to make the public aware of these issues. Perhaps the best way to do this is through their pocket books. The insurance industry is also well organized, has a strong lobby, and has deep pockets for plenty of lawyers. If they were aware of the difference in the cost of potential claims between IBC designs and IRC designs, they would charge higher premiums for the IRC designs. This would bring a balancing factor to the economics of applying the code requirements. As much as I hate insurance companies (no offence to anyone who works for one, a job is a job), I think they are an ally to the engineering community by creating an incentive for structures to be designed for performance and safety.

Ok, I'll step down from the soap box now.

Dmitri Wright
Portland, OR

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