Starting from scratch in designing a steel joist...
Starting from scratch in designing a steel joist...
(OP)
If I were to design a steel joist. And by this I mean structurally design the joist, not lay them out for a building, but actually designing the top chord, web and bottom chord. What would be the code checks to follow from the AISC code book?
For a K series joist I want to use the following:
Top Chord: Double Angles (Equal lengths)36 Ksi
Web: Single Angle (Uncrimped-First analysis, Crimped-Second Analysis)36 Ksi
Bottom Chord: Double Angles (Equal lengths) 36 KSI
Rods at each ends from bottom chord to top chord.
The Vulcraft Manual states the bottom chord to be checked in axial tension only, web in compression, and top chord in axial compression ONLY if panels are less than 24" apart.
I've used Chapters D,E,and F.
D2
E3 & E4
F9
When I asked my boss about this he said we would never design our own joists for a client, we would just assign proper loads for someone like Vulcraft to meet our specifications. The reason I want to learn to do this is that this summer, for my masters program, I will be taking Advanced Strength of Materials and Advanced Structural Analysis. For both these classes we must do a project. I would like to make this one of my projects. However, with my checks on my progress so far I certainly feel their are many other checks I am missing. Any guidance is appreciated.
Thanks,
For a K series joist I want to use the following:
Top Chord: Double Angles (Equal lengths)36 Ksi
Web: Single Angle (Uncrimped-First analysis, Crimped-Second Analysis)36 Ksi
Bottom Chord: Double Angles (Equal lengths) 36 KSI
Rods at each ends from bottom chord to top chord.
The Vulcraft Manual states the bottom chord to be checked in axial tension only, web in compression, and top chord in axial compression ONLY if panels are less than 24" apart.
I've used Chapters D,E,and F.
D2
E3 & E4
F9
When I asked my boss about this he said we would never design our own joists for a client, we would just assign proper loads for someone like Vulcraft to meet our specifications. The reason I want to learn to do this is that this summer, for my masters program, I will be taking Advanced Strength of Materials and Advanced Structural Analysis. For both these classes we must do a project. I would like to make this one of my projects. However, with my checks on my progress so far I certainly feel their are many other checks I am missing. Any guidance is appreciated.
Thanks,






RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...
Just a thought.
RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...
I talked to one of the Vulcraft Engineers recently who said it would be very difficult to replicate their their numbers without SJI because of a number of issues, including:
To minimize member sizes, they don't use K=1.0 for compression analysis. The actual K they use is based on the size, shape, and welds for that member and will often be less than 1.
Their calculations include eccentricity in the joints, ie - what if the truss isnt perfectly coplanar? I believe they assume 1" eccentricity.
Their calculations include eccentricity at the joints, ie - the web members may not meet at a theoretical perfect point due to manufacturing tolerances.
If you're trying to replicate the design for an existing joist, or existing calculations - good luck.
If you're doing it as an academic excercise, maybe these points can be ignored and you can proceed with the design via AISC.
RE: Starting from scratch in designing a steel joist...
Dik
RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...
If you do this for your project, one trick is roof joists in uplift have bottom chord compression so you have to have permanent continuous lateral bracing of the bottom chord.
RE: Starting from scratch in designing a steel joist...
RE: Starting from scratch in designing a steel joist...