1/4/2024 0 Comments Fink steel truss![]() ![]() To illustrate:ġ) when I use a commercial software package I have to satisfy myself of the accuracy of the results from software package because I take liability for the results when I use them and I place my seal on the drawings.Ģ) Liability for faulty advice does not require a contract if I even suggest engineering advice to someone and they follow the advice and they suffer a loss I am liable for the loss and so is my employer even if this happens in my own time. Here in Canada the practice of engineering is more controlled than in the U.S. Here is a typical output for a fink truss showing moment calculations: One thing I found really helpful was the samples provided in the previous editions of the TPI 1, its really quite disappointing to see no such example calculations in the current standard (2007). I've just ordered a copy of Hibbeler's Structural Analysis to further research how best to deal with frames, trusses etc. My biggest unknown with this would be how to deal with the fixity of joints at panel points and heels. If anyone has any ideas on how to do a simple matrix method analysis of a common fink truss please send me in the right direction. For now I've gone with the simplified method which is the method used in the TPI 1-1995 standard, at least I can produce a solution and it is considered more conservative than the current matrix method. However, I need to be able to run this app without doing a full blown analysis using RISA or some other FEA type product. The current spec TPI 1-2007 calls for using the matrix method in determining the moments. I've kind of hit a road block on the moment calculations for my truss designer project. is rather extensive so it may be a while before I can generate the algorithms that address the true engineering aspects of a truss design, however even so the app as it currently stands now is already quite interesting showing the axial internal forces of the members. I've been reading the TPI 1-2007 and the equations and checks for member sizing, deflections etc. Smaller than 24' and the attic space becomes to narrow and in my opinion is hardly worth all the trouble. span will probably be 24' to 30', beyond that the lower chord probably cannot be a 2x12 and would to be an engineered floor truss, so you end up with two trusses in one. This one will prove to be challenging but who doesn't like a challenge. The attic width is a function of the span and the pitch, so I need to determine a realistic algorithm for calculating this width. Unlike your other common trusses though there are more variables that are interrelated here. My other truss I really want to enter is the attic truss. However, if you can send me a couple good pictures of a standard gambrel style truss I can enter it into the code and you will be able to play with its geometry. I'm not particularily familiar with the gambrel truss, most gambrel roofs I've seen are framed up the traditional rafter (stick built on site). Lots of conditions you could address that would be useful for us here. I'd like to see a truss design calculator where the ceiling joists were raised and calculations done to reinforce the top chord between the raised joist and top plate. Also, if you can address rebuilding trusses in existing buildings, to provide additional height, that would be of value for the same reason. It gives such volume, which for our shops and garages, with lifts, and the height restrictions on residential zoning, would be ideal. The one truss design I would like to see you address is the gambrel. When you get the program finished, I will play with it just for fun. So, while dissatisfied at the status-quo, I realized things were the way they were, for a reason. And modern high end houses have too many different conditions, so you are designing dozens of different ones for each house. Designing by hand was too time consuming. Wondered if there was a program I could use to design trusses. A long time ago, in my work in an Architectural office, I did the same thing. ![]()
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