Wind vs Seismic Control, whats appropriate? 5

[xkcstructural]

Situation: an engineer is analyzing a structure and first pass-through determines the Wind exposure category as B, then does the seismic evaluation and finds that seismic controls, but "decides" that they do not want seismic to control and changes the wind exposure to C and then say voila wind controls and I do not need to meet the seismic requirement. I've also experienced it on the flip side where I put a structure in wind exposure category C and its an exisitng structure and meets exposure category C but they say that wind probability will likely never happen and brining the structure up to meet Exposure Cat c is too much for the contractor so treat it as B.

How does this make other engineers feel? For me it raises a red flag about that person's judgment and engineering understanding. I have never had to deal with this kind of environment and I am wondering if my gut telling me that, that behavior is not engineering is in check or am I out of line. Is this behavior okay if they are the EOR?

Lately, I've just been having a bunch of ethical dilemmas and Im the only one concerned about this behavior. Any advice if it is a red flag on how to approach it? I get told I stick to code too much and the probability of that wind event happening is not likely. It feels dismissive and belittling. But if it is the EOR's call then maybe Im asking for no reason and I can have a better understanding of whats acceptable.

 

[Eng16080]

human909, the interior structure is a good example of a clear case where seismic would obviously control over wind.

 

[calvinandhobbes10]

I work in east coast US, low seismic SDC B or A.
Older engineers have told me that a generation ago it was normal practice to determine one controlling lateral force, and deem it sufficient to completely ignore the other. Even put this determination on the drawing notes. Obviously this does not satisfy current building codes. I don’t know 80’s codes or if this is truly a stated provision, but I learned this firsthand and saw it multiple times. Not specific to building type either.

Along with the many stated concerns about your situation, your supervisors may simply be continuing to follow a design approach from their early years. Wouldn’t be the first engineers to pay little attention to Code changes.

 

[phamENG]

calvinandhobbes10 - I see we're both in VA...we may have learned that from some of the same people...

 

[JoshPlumSE]

How does this make other engineers feel? For me it raises a red flag about that person's judgment and engineering understanding. I have never had to deal with this kind of environment and I am wondering if my gut telling me that, that behavior is not engineering is in check or am I out of line. Is this behavior okay if they are the EOR?

This engineer is either unethical or doesn't understand basic engineering principles. One of the first things I learned when I got out of college and started working was that just because Wind controlled the lateral shear, it doesn't mean you can ignore seismic. Why because the seismic shear was based on an assumption related to seismic detailing. Essentially that the connections would allow for a certain amount of ductility. If you don't detail the connections that way, then you don't get the ductility.

If he doesn't understand that, this engineer isn't qualified to be an EOR for any project (IMO) where seismic has ANY possibility of controlling.

 

[phamENG]

where seismic has ANY possibility of controlling.

Josh - do you mean occurring?

 

[milkshakelake]

It could also just be a lax building department letting engineers get away with things, which creates a certain regional practice. For example, I practice in an area where code enforcement is super strict. When I do projects outside this region, I have to lower my engineering standards because things are just done differently. If I don't relax my standards, someone else will do it and take the project. It's not like I'm making the world worse, and I try to be a bit better than the engineers that just slap random lateral systems onto drawings based on experience. I used to work for those kinds of firms.

I visited some states I won't name, and saw stuff I'd never see in my area. Things like completely open job sites with no construction fences. No scaffolding or netting for relatively tall buildings. Sidewalks blocked with no pedestrian protection or flagpersons. If that's the level of safety in those areas, I don't have high expectations about how they deal with seismic and wind.