birthi
Electrical
- Sep 19, 2003
- 5
I have to check the capacity of an existing office floor. The supporting structure consists of truss system with wood chords and steel tube web.
It's from about 1980, and is not manufactured any more (in this dimensions). However, Weyerhaeuser was able to provide me with the ICBO Report (PFC-1694) on that product. It list all the chord specs and the possible web tube / pin permutations and the corresponding tension/compression limits. So far - so good. But apparently the design allowed you some sort of designer freedom. Neither the web tubing nor the pin sizes are the same over the full span. So it tarts off at both ends with 1-1/4" tubes for the first few panels, and with 5/8" pins, and then down to 1" tube and 5/8" pin, and for the majority of the span goes down to 1" tubes and 3/8" pins. That all makes perfect sense, since the shear and consequently tension and compression in the web members is highest at the end, and tapers down to the lowest value in the center. The chord are cut from MicroLam, and their capacity is out of question. Now, the tricky point is, besides tube diameter and pin size, the tube gauge is also playing a role. And can measure everything on-site, but not the gauge of the tube walls. I realized there is color coding on the tubes, red, black and blue.
Unfortunately the ICBO report does not mention any color coding. Has anyone come across that type of coding?
Thanks!
Herbert Birthelmer
It's from about 1980, and is not manufactured any more (in this dimensions). However, Weyerhaeuser was able to provide me with the ICBO Report (PFC-1694) on that product. It list all the chord specs and the possible web tube / pin permutations and the corresponding tension/compression limits. So far - so good. But apparently the design allowed you some sort of designer freedom. Neither the web tubing nor the pin sizes are the same over the full span. So it tarts off at both ends with 1-1/4" tubes for the first few panels, and with 5/8" pins, and then down to 1" tube and 5/8" pin, and for the majority of the span goes down to 1" tubes and 3/8" pins. That all makes perfect sense, since the shear and consequently tension and compression in the web members is highest at the end, and tapers down to the lowest value in the center. The chord are cut from MicroLam, and their capacity is out of question. Now, the tricky point is, besides tube diameter and pin size, the tube gauge is also playing a role. And can measure everything on-site, but not the gauge of the tube walls. I realized there is color coding on the tubes, red, black and blue.
Unfortunately the ICBO report does not mention any color coding. Has anyone come across that type of coding?
Thanks!
Herbert Birthelmer
