This is more of a discussion coming out of frustration and also trying to get a clear understanding. Have our company standards been conservative all this time?
I think the new Code books that roll out should specify Tile deflection. In a majority of firms that i worked at, we use L/480 for tile loading all the way up to L/600(ceramic). Now we are Runing into a situation because of one structural firm using L/360.
A little background and information. The situation is one Architectual firm we work with are our bread and butter, so we cannot just tell them to kick rocks. We have always worked on their office buildings which a lot included tile loadings(ceramic). No issues, However, recently another engineering firm was hired to do something small scale in UTAH(we did not have time to take the project), the situation now is that they are questioning if we are conservative because for office buildings, we have a standard for composite deck on steel beams. Our tile deflection is L/600 to .3~.5 to 1" (depending on span and situation) we can have beams spanning anywhere from 10 to 20 feet, and girders spanning 20 to 60 feet.
so, the came to us questioning our designs based on the structural firm that was hired to do the small-scale project. it is a composite deck with w8x15 beams spanning about 10 to 12'-0" with a live load of 50psf. The deck spans 8'-0" with 2-span to 3-span conditions.
So at the end of the day, if we are going by code, It works. It meets the Live Load of L/360 and TL/240. They want us to design the same way. We tried pushing against it. We explained and justified the situation, but it came down to "does it meet code, yes then design it that way." So now there are local deflections of about .8" and global deflections of over 1", but Per code It WORKS!!!! Code only specifies Local of L/360 not Global.
So at the end of the day, we did design our office building Per IBC Code Minimum. Which yes, they saved TONS due to reduced steel weight. They increased the clear distance of their floors which is also great, and we understand we won't be responsible for any damages or cracks or other issues that might occur due to the low deflection limit. But we still don't like the idea of designing it per that low of a limit.
The lead engineers in the office are basically thinking about it and are deciding to just start designing per code minimum. Because if our standard doesn't change, the company loses over millions of dollars a year of revenue from the client.
Unless we have been conservative all this time? We can only justify it as a rule of thumb and experience. Essentially, it's not enough, and per code it's L/360. Also, the L/600 comes from masonry design, so it's something that we cannot really justify. It's based on engineering judgment, but It still came back to code minimum is L/360.
Btw, i don't mean to make it sound like the architect firm are A*Holes. We had a civil and good discussion and they have listened fully because it's an important issue for us and them. They understand the code very well, but it's coming down to the client being saved tons of money and it still meets code minimum.
We have come so far with code books, yet code still does not give us a definite answer and are leaving it up to us. That's great and all, but now another firm might be added to a list of firms who design tile loading deflection of L/360 and a not-so-great global deflection. FYI, we still make sure vibration is okay!
Unless this is truly okay? Maybe our firm has designed everything conservatively?
I think the new Code books that roll out should specify Tile deflection. In a majority of firms that i worked at, we use L/480 for tile loading all the way up to L/600(ceramic). Now we are Runing into a situation because of one structural firm using L/360.
A little background and information. The situation is one Architectual firm we work with are our bread and butter, so we cannot just tell them to kick rocks. We have always worked on their office buildings which a lot included tile loadings(ceramic). No issues, However, recently another engineering firm was hired to do something small scale in UTAH(we did not have time to take the project), the situation now is that they are questioning if we are conservative because for office buildings, we have a standard for composite deck on steel beams. Our tile deflection is L/600 to .3~.5 to 1" (depending on span and situation) we can have beams spanning anywhere from 10 to 20 feet, and girders spanning 20 to 60 feet.
so, the came to us questioning our designs based on the structural firm that was hired to do the small-scale project. it is a composite deck with w8x15 beams spanning about 10 to 12'-0" with a live load of 50psf. The deck spans 8'-0" with 2-span to 3-span conditions.
So at the end of the day, if we are going by code, It works. It meets the Live Load of L/360 and TL/240. They want us to design the same way. We tried pushing against it. We explained and justified the situation, but it came down to "does it meet code, yes then design it that way." So now there are local deflections of about .8" and global deflections of over 1", but Per code It WORKS!!!! Code only specifies Local of L/360 not Global.
So at the end of the day, we did design our office building Per IBC Code Minimum. Which yes, they saved TONS due to reduced steel weight. They increased the clear distance of their floors which is also great, and we understand we won't be responsible for any damages or cracks or other issues that might occur due to the low deflection limit. But we still don't like the idea of designing it per that low of a limit.
The lead engineers in the office are basically thinking about it and are deciding to just start designing per code minimum. Because if our standard doesn't change, the company loses over millions of dollars a year of revenue from the client.
Unless we have been conservative all this time? We can only justify it as a rule of thumb and experience. Essentially, it's not enough, and per code it's L/360. Also, the L/600 comes from masonry design, so it's something that we cannot really justify. It's based on engineering judgment, but It still came back to code minimum is L/360.
Btw, i don't mean to make it sound like the architect firm are A*Holes. We had a civil and good discussion and they have listened fully because it's an important issue for us and them. They understand the code very well, but it's coming down to the client being saved tons of money and it still meets code minimum.
We have come so far with code books, yet code still does not give us a definite answer and are leaving it up to us. That's great and all, but now another firm might be added to a list of firms who design tile loading deflection of L/360 and a not-so-great global deflection. FYI, we still make sure vibration is okay!
Unless this is truly okay? Maybe our firm has designed everything conservatively?
