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?

 

[Ron]

In forensic investigations, one fact is rarely sufficient for a conclusion, particularly with structural systems. While facts may be indisputable, the interpretation of facts that lead to conclusions from two different engineers can be different. This is common and has little to do with credentials, assuming both are capable, competent engineers practicing to their standard of care.

If you believe the structural system has been compromised ( I agree with dik's terminology here....compromised rather than damaged), then your task is to accumulate enough facts to prove your point. That might require more field investigation, more computation or both.....but that all requires more cost to your client. If the value of the claim is high, it might well be worth it to your client to have you expend more effort to prove your point. If you feel strongly that the compromise may affect the health, safety or welfare of the public (in this case the "public" is the homeowner), then you have a duty to carry it through to a conclusion while charging for your services. If your client refuses to go further, you have to state your opinion in writing to them and recommend further investigation for your own protection.

Your premise implies that this project is either in litigation or headed there. Assuming that, you probably are working for or with an attorney. The attorneys I work with do not care in the least that my opinion might be different than the opposing side's expert....in fact they usually expect it. What they also expect is for me to be right in my conclusions and opinions and be able to support those through rigorous disagreement with the other side and equally rigorous cross examination during depositions and trial if it goes that far.

Through legal discovery you will learn your opponent's method for arriving at his/her conclusion. I have seen highly qualified experts rely solely on the fact that they are recognized as such and do little to back up their opinions in the way of physical evidence, studies or precedent engineering. The fact that the other engineer has another opinion should not sway your judgment in any way. Prove your point and stick to it.

 

[Ron247]

I do not know if this will wind up in court, but I guess there is always a chance. As far as differing conclusions, I see that all the time. I even see it from people working for the same company. This roof was just something that got me thinking about how engineers collectively view the difference in Facts, Conclusions and Opinion. From that discussion, I see we may also define structural system differently.

As far as I know, there is no issue about whether the roof will get repaired, it will be repaired at the insurance companies expense. I think they easily agree to that. I was also questioning the statement there was not any damage to the structural system. To me, there was damage but the system was still capable of functioning.

 

[Tomfh]

To me, there was damage but the system was still capable of functioning.

You could make the same argument about cutting an inconsequential new opening in a load bearing brick wall. In which case was there really damage to the structural system?

 

[Ron247]

Good point Tomfh, but if I were to intentionally cut a 1" diameter hole, I would not call it "damage". If the tornado had driven a 1" diameter pipe through the brick, I would have called it damage. The key words in your example are inconsequential and damage. Regardless of the hole size, if I wanted to put a hole in a shear wall, I could still calculate the capacity of the modified wall and determine it is adequate. I would not refer to my modification as damage even though it lessens the strength a little. If the hole did no reduction in strength, then I could put 1,000 holes in it of the same size.

 

[Enhineyero]

Maybe use the phrase- 'no longer in its likely original condition' rather than the word 'damage'.

 

[Ron247]

That is a good suggestion Enhineyero.

 

[Teguci]

In this industry, a fact, conclusion and opinion are all the same when the engineer of record puts his stamp on it. He has both the responsibility and the authority to vouch for his position. God will let him know when his facts are actually opinions.

 

[rb1957]

"If the hole did no reduction in strength, then I could put 1,000 holes in it of the same size." … well that's "reductio ad absurdum" … 'cause 1 small hole doesn't impact the structure, doesn't mean that 1000 of them won't either.

How the hole got there (purposefully drilled or tornado impact damage) could well affect the structural impact (ie collateral damage due to impact ?).

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

 

[Ron247]

rb1957, I guess I do not understand the "inconsequential hole" that Tomfh noted. Tomfh, please explain what you originally meant by that. I see more than one possible interpretation and I am sure there are some I did not think of.
[ul]
[li]It did not reduce the strength of the wall at all regardless of where it was placed.[/li]
[li]It was so inconsequential its impact is minute and not worth calculating.[/li]
[li]The placement of it is not in the location of maximum stress and therefore is inconsequential.[/li]
[li]The placement of it is not in the location of maximum stress and therefore is inconsequential even though it reduces the strength at its location.[/li]
[/ul]

rb1957, what do you take it as meaning? I took it as meaning the 2nd bullet.

 

[Tomfh]

Ron,

By “inconsequential” I meant the roof diaphragm (or load bearing brick wall) still worked fine despite the hole(s).

Personally I wouldn’t draw a distinction between whether a hole is intentional or whether it’s an accident. A hole is a hole, and the structure either works with the hole there or it doesn’t. It doesn’t make sense to me to say a hole is ok because a person intentionally cut the hole, but not ok if a tornado did it.

 

[rb1957]

wouldn't a tornado be more ham-fisted than a guy with a drill (perhaps not ?) and so the tornado damage could be more impactful to the structure than the intentionally drilled hole.

@Ron, point 1 is clearly not true in the absolute sense. Point 2 is pretty close, if one assumes that checking the stress in the area of the hole; possibly the person assessing is totally familiar with the stress map and is doing a cursory check from memory. Point 3 is more thorough than 2, if the hole was at a critical area of the structure I'm sure we'd do something more than a "hand wave"; possibly the structure is designed with a low margin so a hole may be a concern were ever it is. Point 4 is more complete.

The hole will reduce the strength of the structure, but by how much. In typical structures the impact would be negligible but there are scenarios where some review would be warranted. Sure, we can analyze every single minor change, but that it not an efficient use of our time (or our life-force).

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

 

[r13]

A calculated act vs uncalculated. The former results in an engineered product, the latter produces unpredictable damage on the structure, that usually requires follow up engineering evaluation, and engineered solution for remediation.

 

[rb1957]

so you have a room for judgement, for experience ?

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

 

[r13]

Yes, engineering judgement is very important in many occasions. It is formed based on engineering principles, not guesses.

 

[Ron247]

My point on tornado versus drill assumed the holes were the same, just different ways they came to be. But I would refer to the tornado as damage but not the drilled hole. I would call it a modification. The terms more reflect how the hole came to be rather than its impact on the structural system.