Pylon Sign HSS Torsion Tube Connection
Pylon Sign HSS Torsion Tube Connection
(OP)
I am looking for advice making connection to HSS square tube with torsion load, wall thickness of the HSS tube, and bracing or stiffening requirements.
My customer has an existing two column pylon sign and wants to use the existing foundation and 18" of existing 10"x6" HSS columns spaced 104"OC. The new sign has 8"x4" HSS columns spaced 87"OC, factory welded 16"x12" base plates, and 4 - 1.25"bolts spaced 13"OC and 9"OC. I plan to: weld end caps to a horizontal 114" long 10"x10" torsion tube; weld 16x12 match plates spaced 87"OC to top of torsion tube; weld 4 - 3"x3" gussets spaced 4-5"OC to bottom of match plate and sides of torsion tube. Each column has 1500 lb wind load from sign face at 15' above grade so 20 kip.ft moment at 18" above grade top of existing column.
My customer has an existing two column pylon sign and wants to use the existing foundation and 18" of existing 10"x6" HSS columns spaced 104"OC. The new sign has 8"x4" HSS columns spaced 87"OC, factory welded 16"x12" base plates, and 4 - 1.25"bolts spaced 13"OC and 9"OC. I plan to: weld end caps to a horizontal 114" long 10"x10" torsion tube; weld 16x12 match plates spaced 87"OC to top of torsion tube; weld 4 - 3"x3" gussets spaced 4-5"OC to bottom of match plate and sides of torsion tube. Each column has 1500 lb wind load from sign face at 15' above grade so 20 kip.ft moment at 18" above grade top of existing column.






RE: Pylon Sign HSS Torsion Tube Connection
BA
RE: Pylon Sign HSS Torsion Tube Connection
RE: Pylon Sign HSS Torsion Tube Connection
I attached a sketch. Any comments would be appreciated.
https://res.cloudinary.com/engineering-com/image/upload/v1431525694/tips/150454_Sign_Engineering_-_PPE-21839_wy7jbi.pdf
RE: Pylon Sign HSS Torsion Tube Connection
RE: Pylon Sign HSS Torsion Tube Connection
RE: Pylon Sign HSS Torsion Tube Connection
RE: Pylon Sign HSS Torsion Tube Connection
BA
RE: Pylon Sign HSS Torsion Tube Connection
RE: Pylon Sign HSS Torsion Tube Connection
My initial concern was similar to SAIL's stability concern. Since the new 8x4 is OK in bending and during Load Case 2 each column carries 70% of total sign wind load the existing 10x10 columns are much stronger and stiffer.
??? I'm not sure how to compare torsion tube strength and stiffness to upper column. ???
RE: Pylon Sign HSS Torsion Tube Connection
I have a few aversions in design and one of them is cantilevering a col off a bm. In spite of the fact that all the forces may be accounted for, I still would go to any length to avoid it. So I would prefer sketch 2 as the connections are more clean and direct and it also gives one the flexibilty of varying the length "L" to obtain forces that can more easily be dealt with.
RE: Pylon Sign HSS Torsion Tube Connection
BA
RE: Pylon Sign HSS Torsion Tube Connection
Why not use a 12" o.d. pipe by 110" long (out to out of the lower columns for the torsion tube. Cut the top of the lower columns to fit the 12" pipe and apply an end pl. which laps the outside faces of the lower columns. Cut the base plates off the sign columns and cut their bottom ends to fit the 12" pipe. You will want to install inside stiff. pls. in the torsion tube, at the two webs of each of the sign cols. and at the inner webs of the lower cols. If you put one end of the 12" pipe up on a saw horse, and roll the pipe as you weld, these stiff. pl. welds are all down hand. Weld the end pls. on the torsion tube and weld it to the sign columns. Then the only field welding is around the lower columns to the torsion tube and end pl.