Facts versus Conclusions versus Opinions/Beliefs 2

[Ron247]

I am working a project where I somewhat disagree with another highly qualified engineer that represents the other side on a structural topic. The building was subjected to high winds that tore off at least 1/4 of the metal roof panels. This is a house that appears to be stabilized by diaphragms and shear walls other than the timber piles it sets on to make an elevated structure. The roof appears to be a major diaphragm for the MWFRS. If at least a 1/4 of it was damaged, would you make the statement, "The structural system was not damaged."

We agree on the facts, but it appears we disagree on the conclusions we both arrive at. I want to be fair, but even though their credentials trump mine, in my opinion, to me it is obvious the structural system "was damaged to some degree". Even though it was not damaged enough to cause a serious collapse, I cannot see stating there was not any structural damage.

This now leads me to my philosophical discussion on Facts, Conclusions and Opinions. How do we as Engineers define these terms? I will give one example with my beliefs.

There is a clock on the wall with the big hand on the 12 and the little hand on the 2. Let us assume this is a fact.
It is 2 o'clock is a conclusion but not a fact. Agree?
2 o'clock is a nice time of day is an opinion but not a fact or a conclusion. Agree?
The more facts you amass towards proving your conclusion can make your conclusion become more probable as a fact. Examples,
[li]I have confirmed the clock is electric and it is plugged in a working outlet.[/li]
[li]I have confirmed the clock actually works.[/li]
[li]When the clock displayed 2:00 o'clock, the sun was fairly high in the sky which proves it was 2 o'clock is a conclusion[/li]

Thoughts?

 

[human909]

A very open ended question that I'm not sure where I expect the discussion to go. The reality is that terminology and opinions differ. And there are plenty of people who will refuse to facts or reason no matter how many facts you throw at them. This applies as much to engineers as it does to a frothing at the mouth political zealot.

For example, I've alerted senior people in my organization that their approach to calculating XYZ is fundamentally flawed and doesn't take into account W, often W is relatively minor. Their response has generally been "its what we have used for more than a decade". A recent project that we have taken on but not finished has a very significant W.... I'm curious to see the outcome. (Failure in this case would be embarrassing, but not harmful.)

That is life. There are always some people in this world that aren't open to facts and reasoning on some or many issues. If their senior to you in an organisation you can only push things so far. Assess the consequences and decide the way forward from there.

 

[Ron247]

My purpose was to get others opinions as to what constitutes a fact versus a conclusion. How many times have we heard your can have your own opinion but not your own facts or something like that. To me, facts are literally indisputable. They can be fairly easily proven. The structural system not being damaged is viewed by some in that discussion as a fact, not a conclusion. The only fact I saw was that a portion of the roof was missing. I concluded the roof was part of the structural system. I concluded the structural system was damaged to some degree.

In many cases we differ on conclusions, not facts. You are correct in that engineers are human and therefore we can act like the political theater at times. The more information we gather can make our conclusion approach being a fact.

 

[bridgebuster]

Facts are based on evidence. If you need a philosophical answer perhaps look for a Jesuit who is also a structural engineer. I'm sure there are some out there.

I'm a bridge engineer with little building experience. However, we could make an analogy that the roof panels are the equivalent of a bridge deck and the deck is part of the structural system (bridge deck and supporting members, ie, stringers or girders and diaphragms). If I looked at a bridge that lost part of the deck, I would say the structural system is damaged. Then based upon my observations of the framing I could further state if the framing members were or weren't damaged. To me, it seems that your question is about whether or not it's valid to tell your client that the system can be restored to the as-designed condition.

 

[dik]

What is the strength of the existing diaphragm? If adequate, then the statement could be correct, albeit, somewhat compromised...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[skeletron]

In really broad stroke terms, "facts" should be able to be proven in multiple ways without relying on differing sets of assumptions. Usually this can be done quantitatively and qualitatively. "Conclusions" rely more on the set of assumptions that direct the trajectory.

 

[BAretired]

BA[/color]]I am working a project where I somewhat disagree with another highly qualified engineer that represents the other side on a structural topic. The building was subjected to high winds FACT that tore off at least 1/4 of the metal roof panels FACT. This is a house that appears to be stabilized by diaphragms and shear walls other than the timber piles it sets on to make an elevated structure OPINION. The roof appears to be a major diaphragm for the MWFRS OPINION. If at least a 1/4 of it was damaged, would you make the statement, "The structural system was not damaged." QUESTION

We agree on the facts, but it appears we disagree on the conclusions we both arrive at. I want to be fair, but even though their credentials trump mine, in my opinion, to me it is obvious the structural system "was damaged to some degree". Even though it was not damaged enough to cause a serious collapse, I cannot see stating there was not any structural damage.

You have itemized two facts, two opinions and one question (see red text). The expression "appears to be" is stating opinion, not fact. You may agree on the facts, but not necessarily the opinions, hence you could have different conclusions. To explore your differences, it may be necessary to discuss the term "structural system" and possibly other factors.

BA

 

[r13]

to me it is obvious the structural system "was damaged to some degree"

The controversy here is the definition of "structural system". Personally, I think the roof deck is more of cladding, rather than a structural element in the main force resisting system. The damage renders inconvenience to the occupants, but not immediate risk as if there is a "structural damage".

 

[Enhineyero]

Facts are truths, truths are evidenced-based. Everything else is an opinion.

In your case best to define what 'structural system' is. If you assume that the roof sheeting is part of the structural system (because of diaphragm action required to transfer lateral loads) then clearly state that.

 

[Tomfh]

What is the dispute?

Is the other engineer saying the diaphragm (Whilst possibly damaged) is not part of the structural system, or is he saying diaphragm has sufficient residual strength that the holes do not constitute structural damage?

 

[Patrick Manley]

The confusion comes in when we start to refer to finish materials or non-structural frame elements as
"structural." IF we muddy the water, then technically everything becomes structural. Gypsum board reduces vibration, furniture dampens the bounce in a floor, and so on. Are these elements structural? Heck no.

I agree with the engineer who maintains there is no structural damage. What was damaged are other portions of the building that are secondary to the structure.

Does the use of diaphragms such as a metal roof cloud the terminology? Only if you let it by making a n historically precise term too wide and vague.

 

[phamENG]

On the philosophical: if you're in the US or are even tangentially aware of American politics, you know that facts are frequently questioned and debated. If you've studied Socrates, you may be familiar with the trouble of determining what facts are and even what knowledge itself is. Strictly speaking, there's no end to the level of questioning you can subject a supposed fact to. Of course there are practical limits, but those can vary depending on who's involved, what the issue is, and what the consequences are. Generally speaking, and applying those practical limits, I would tend to agree with your clock example. Now if 2pm happened to be the time of my execution, or a deadline that made or break my fortune and family's well being, I might try to put up an argument.

On the current situation, I think BA brings up some fantastic points, and Patrick Manley might be on to a key point here. How did you determine that those metal roof panels were part of the diaphragm? You didn't go into much detail on the overall construction of the house, but from my experience practicing in coastal Virginia and my memory growing up on the Gulf Coast (and working briefly as a residential construction laborer), elevated houses on timber piles are typically wood framed with plywood roof diaphragms and some sort of roof covering over top - shingle, standing seam metal, etc. With the exception of backyard tiki bars and other low impact structures, I don't know that I saw any that had metal roof deck over wood framing. Not to say it can't happen, and I've seen pictures from the tropics and developing nations, but I haven't encountered it in the States. So without any other specific knowledge of the house in question, I would guess from your description that 1/4 of the standing seam metal roof was damaged, but the diaphragm itself (the plywood underneath) was not. Those metal roofing panels are paper thin and do essentially nothing for the structure and are really just a longer lasting shingle. Some of the PEMB outfits have started using them as diaphragms in recent years, but they're typically thicker than your standard residential metal roof panel.

 

[Ron247]

The roof was metal panels on wood purlins. The 2x4 wood purlins were fastened to a conventionally framed roof (rafters and ceiling joists). Metal roof panels can serve as a diaphragm regardless of their thickness. The thickness will dictate how well they can serve as a diaphragm. Assuming the roof panels were the diaphragm and 20% was damaged. If the remaining 80% was strong enough to serve as the diaphragm, one could say maybe say the structural system was unharmed, but I would say it was harmed but sufficient to function. In both cases, I would call these points a conclusion, not a fact. If I do not see any other mechanism to transfer wind load to the shear walls other than the roof panels, I concluded, the roof panels were the diaphragm.

That is the main point of this posting. Facts, Conclusions and Opinions. To me, facts are provable. We reach conclusions by observing facts, gathering information and applying science. Opinions are when we have little scientific evidence, but believe something. My opinion is that blue is a nice color. I have no scientific basis for that opinion.

I highly respect BARetired's guidance but see we disagree on a conclusion versus and opinion. The more information I gather that supports a conclusion I have made, the closer my conclusion can move towards being a fact, but it rarely will actually become a fact. The more information I gather that refutes my conclusion, the more it moves towards being an opinion . We may call conclusions, our "professional opinion", but I myself do not refer to the application of scientific principles as an opinion.

But again, that is the purpose of the post. To see how much our "opinions" vary. So to me the bookends are fact and opinion with conclusions being what engineers deal in. Facts and opinion do not require us to be engineers. Conclusions do.

 

[Ron247]

To explore your differences, it may be necessary to discuss the term "structural system"

I think that is a good point. Do we even agree on a definition of structural system? I failed to notice that we may have somewhat different definitions of it. Maybe my posting is more related to the definition of structural system than fact, conclusion and opinion issue.

 

[rb1957]

it could be 2am ? (so "sun being high in the sky" is not "proof") ... be open to other interpretations of the data.

another day in paradise, or is paradise one day closer ?

 

[phamENG]

Ron - I stand corrected on the case at hand. I'm not used to seeing that in anything but barns and other outbuildings (maybe a porch or two, now that I think about it).

So then there's the question of the structural system. I don't think this changes the point of the post (though it's your post, so maybe it does?), but rather looks at a particular case of how facts, conclusions, and opinions can come into play.

Few cases are simple conclusions built on immutable facts. The facts are often difficult to discern in the best of times, and we often have to use judgement built on experience to make conclusions about conclusions about conclusions about what are probably, maybe, plausibly facts. So when there's a disagreement, it's probably because one of the many layers of conclusions (or worse yet, an opinion) has been mistaken for a fact by one or both parties.

 

[bridgebuster]

As Harry S Truman liked to say on vacation "It's noon somewhere in the world". That's a fact!. - apologies to HST, eng-tips doesn't have a Bourbon bottle emoticon.

 

[r13]

A diaphragm has important role in building stability and is required for the building to perform intended functions - carrying human activities and sheltering. The damage of the roof panels impairs the building's service function, but will the loss of diaphragm action causes instant instability is to be determined by other supporting facts. Here, the unarguable fact is clear - damages on roof panels, but, whether the damages cause the loss of stability is the conclusion you have to make after sorting through the other supporting facts in the design. All other talks beside the parties directly involved in the facts gathering and evaluation are opinions.

 

[Ron247]

rb1957-My point was that if the sun was high in the sky is a fact. The fact supports a conclusion of 2 o'clock but if the sun had been on the horizon, it would have refuted the conclusion for most parts of the world but not all. If the sun was not up at all, it would not support or refute the possible time. I was not taking it as proof, I was just was drawing conclusions about a clock on the wall.

 

[Ron247]

phamEng-The roof panels were not the low rib and thin kind you see on a sheathed roof. They were closer to what you would see on a PEMB. The PEMB is a good example of how we may design something to be the MWFRS but something else actually acts as the system until it fails. I have seen hundreds of PEMBs with braced bays to serve as longitudinal bracing. The wall rods are loose or have been removed but the building still stands. The wall panels act as a diaphragm even though we did not design them to be one. They will resist wind until they fail or rack enough to engage the rods, then the rods go to work (assuming they are still there).