Hi, I am a "young" engineer practicing structural engineering.In the above, the reader essentially asked three questions on structural engineering practices that he has observed in the Philippines:
I would like to ask why, As i have observed, engineers in our country use the AISC code to design LC members (cold formed light gage steel). Our NSCP code for steel is purely based on AISC but most structural engineers here use this to design Cold formed shapes (mostly LC for purlins or girt). design of LC is suppose to be done under AISI code. Although the AISI and AISC have almost the same factor of safety for bending using ASD, the AISI code has more reduction factors for sectional properties, unlike the AISC code. I don't know if they are not aware of this or its just simply inconvenient to find a copy of the AISI code so they just use the AISC code (which the code we use for steel in our NSCP 2001). Please correct me if I am wrong regarding this.
ALso i have also noticed that some designers does not check the other requiremenet for SMRF(concrete) which is required as a special provision for seismic requirement. most of what i have seen is that they only check it for the basic stress requirement. If we do not satisfy the special provision requirement the structure will not achieve its required ductility, thus resulting to non compliance of the NSCP code.
Lastly, I don't know if the gov't people who issues building permit reviews the structural calculation of the engineer prior to issuance of building permit. because i have seen some calc. which is errorneous and yet a building permit is still issued for the project. indeed strucutral engineering practice has a long way to go for improvement in our country
- Use of AISC instead of AISI provisions for cold-formed, light gage steel members.
- Partially satisfying requirements for Concrete SMRF systems
- Building permits being issued to erroneous structural calculations?
Hi, I wonder what is your real name, "Juan Dela Cruz"? For now, I will consider this as an anonymous post and it is perfectly understandable to do that. Indeed, when I myself was "young," I would notice similar things such as this, and they are very legitimate observations. And it's not to say that I don't observe these same things now. But these are very touchy subjects which should be handled with care openly or publicly. That is my intention in this reply to your questions. I should begin by saying that I do not know everything, but whatever I know and can share I will share.
I may have witnessed or heard of the same things and all this, I believe can trace its roots to two things, education and resources. And then it is further compounded by economics.
On the use of AISC instead of AISI provisions for cold-formed, light gage steel members:
From my own experience, I never knew the AISI and its specifications/manual existed not until after college and getting my license, and only already years into my life as an engineer. To this date, I am still not as familiar with the AISI as I am with the AISC. But rational thinking would tell us that certainly there are differences between cold-formed, light gage steel members and regular, usually hot-rolled or sometimes built-up, structural steel members, and the treatment in design for different materials should also have some differences. But as you have pointed out yourself, there are also some similarities. Still, certainly the AISI specifications would still be more appropriate, even if the design comes out okay when the AISC is used - "right for the wrong reasons."
So my point here now is that many of us don't know that a group such as the AISI exists, a group different from the AISC, and some of us might know about the AISI and their specifications for cold-formed steel design, but like myself some don't know the provisions as well as, say, those in the AISC, ACI, UBC, or IBC, and so on. This is where, really, I think, education is the solution. It could start from a little insertion in undergraduate curricula. It could be as simple as inserting one track in ASEP conventions to make people aware. However, these are not things that we could just expect or demand of people in academia or even ASEP. I think, if you want something done, you offer your help. You go be active in ASEP, and eventually become a committee member and even an officer, and then do something about it. That is the pro-active approach, which I think is the best approach compared to all these people saying valid but negative criticisms about all the other engineers and so on, which in turn is bad for the profession.
On the other hand, for some people like myself who know of the AISI, resource availability is a problem. I do not personally know anyone who has a copy of the AISI that I can borrow, and I do not have enough money to get my own copy, nor do I have enough projects to justify investing in even one copy. Maybe the ASEP or some structural engineer friend of mine has a copy, but I do not know. I guess people don't talk about it so much, and that just illustrates further the need for more education. Maybe people don't talk about it so much, exactly because people aren't as familiar with it as they are with the AISC and so on. Because certainly I hear plenty of discussions about the AISC and the ACI and all the other "usual codes." And then of course, the AISI itself is not so much referenced in the NSCP, not as much as the other "usual codes" are. Because the NSCP as a resource is already easily accessible, I guess incorporating AISI provisions in the NSCP is another solution towards education.
At this point, the unavailability of resources is further compounded by economics. Some very determined, business-minded owners, need some cold-formed steel members designed. To bring costs down and increase their economic value, they hire newly graduated, recently licensed engineers. To earn a little extra money because their current salaries are not enough, these new engineers make do with what they know from their education, and with what resources they have available - usually knowledge only about regular steel. It is a sad picture, but it is the reality and it is difficult to point fingers at anyone. Again, I personally think that the best solution is the pro-active approach. Do something about it.
I guess this is why I think I'm not so "young" anymore - because if it's something I can't give any help to, I just shut up and work towards finally being able to help. This altogether is a different topic so I won't expound further.
Just one last thought: one thing you could do is to write a paper showing the difference between using the AISC and the AISI provisions that would illustrate the possible deficiencies in design as you have pointed out, and present it at an ASEP or PICE convention.
On satisfying only partially the requirements for Concrete SMRF systems:
This is something I've seen as a potentially big issue in general because from the code-compliance viewpoint it affects many building designs done even by the most popular of our structural engineers. From the safety viewpoint, maybe those buildings are safe but maybe not and we can't really say. We can only evaluate them for code-compliance at the very least or perform performance-based evaluations which would mean additional time and expenses though.
My response to this question is the same as above, except that I should point out that particularly for tall building projects, economic constraints and resource unavailability shouldn't be issues anymore. Of course, many structural engineers know of some people who unethically lower their professional fees to monopolize the business and therefore those two factors (economics and resources) come into play again, for everyone. It all boils down now to understanding of the code (professional education), and how best to communicate such requirements to the client (educating the client).
Certainly experience or expertise can teach us to understand the code as it was intended, and lack of it, as in my own personal experience earlier in my career, leads to misunderstanding of the code requirements, which leads to some "misses" in the design as in this example you have pointed out. Obviously again, education is key here. Again, these are things not typically taught in undergraduate courses. Maybe no one will ever teach you these things, and you yourself have to find out for yourself and make sure you are doing the right thing, particularly when you are taking responsibility for the design and effectively but only to some extent for the lives being affected.
Again, it is possible (though I think unlikely) that the design will come out satisfactory when checked properly against all code requirements, but again that would make it only "right for the wrong reasons," which is never good for everyone.
Sometimes, experience may have shown some engineers that certain provisions govern over others. So if there are two requirements to be satisfied and by my experience one always governs over the other, then for future projects I could choose to not anymore check compliance to the other requirement, particularly when it is very tedious to do so. If it is an easy check to do, I don't see why I should ignore that check. But I still can. This is called "design," after all. We are allowed to exercise what we call "engineering judgment." If we are absolutely wrong in our design though, we should be responsible enough.
Now it's been a while since I last looked at these specific earthquake engineering provisions you are talking about, but if you can be more specific about that "other" requirement you were mentioning, I could give an even better response. Like maybe it is something that could be ignored.
To tell you the truth, some experienced engineers I know make even worse assumptions than what you have described. They consider a frame as an SMRF for as long as there are columns and beams, and they follow (as best they can) the detailing requirements for such. As you have pointed out, if 1 + 1 = x and x > 1, x - 1 is not necessarily equal to 1. Again I think the key is again, pro-activeness. In this specific case, it is constant self-education. To become an expert, you have to delve into these codes and other literature on a regular basis. In my opinion, any number of years of experience cannot make you an expert unless you truly are, and it is based on what you know. So, read, read, read, and encourage and/or educate others as well.
Building permits being issued to erroneous structural calculations
Ah, yes. This might be one of the touchiest of the three you mentioned. It could be that some city engineers who issue building permits even to those with erroneous design calculations have the attitude of "the design is the engineer's responsibility anyway, not ours." And then again, their job might be just to check completeness and comprehensiveness of submittals. Maybe if they see only a 1-pager of structural design calculations, then they might suspect and disapprove. Or maybe, they're not any more knowledgeable in building design anyway compared to the engineers, so how can they check (i.e. they have to know more than the engineers do to really perform a complete check).
I personally would be more annoyed if they take longer to approve than if I paid them "overtime" fees, because at this point I would be confident about my work. Though of course I am not saying I don't make mistakes - everyone does, even very experienced engineers (which unfortunately some of them cannot admit or take responsibility for)! So anyway, this is something that I can't do anything about so I say nothing about it. The only thing I can do something about is learn more, and do my own complete checks before submitting.