Schifflerized Angles

[engagarcia]

Does anybody know anything about Schifflerized Angles??? Latticed triangular base steel towers have been used as communication structures. The legs of these towers generally consist of "schifflerized" angles (90º equal leg angles bent to 60º)

 

[transmissiontowers]

Yes, we have a couple of the triangular microwave towers in our system that use these 60° leg angles. Are you trying to analyze the structure? We usually get the manufacturer who supplied the tower to analyze the structure. The EIA/TIA may have some hints on how to analyze them.

If you have PLS-TOWER, it will analyze the tower if you can get the leg properties.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[engagarcia]

I´m trying to evaluate this structures with Mstower and Tower, but I have to prepare the data base for Tower. By the way, does any steel manufacturer provide 60º angle member, or in contrast, should i buy a machine to bent this angles???
Thank you

 

[transmissiontowers]

I'm not sure if anyone produces these angles. I would ask a few steel angle suppliers to see if they are produced for a decent price. If you order enough tons of these angles, you may find a steel mill that will hot roll them for you.

The other problem is finding the rx, ry, and rz for the shape plus find out where the neutral axis has moved. I guess I would start with google to see if anyone has the properties tabulated or supplies them.

Have you read the EIA/TIA 222 rev F or G to see what they say?

I have a friend at work that used to work for Rohn and I'll ask him about the angles. Rohn was/is a producer/designer of these 3 leg M/W towers but I think they used pipe or solid round legs with welded gusset plates.

Do you use TOWER from Power Line Systems? If you do, they have good tech support and can tell you where their other customers go to get properties.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[Cloudancer]

Radian used to have a Schifflerizing bender and when they moved their manufacturing to the U.S. then sold it off I believe their equipment was at the Rohn factory in Peoria, IL. You can contact Dave Brinker their VP of Engineering at 309-633-6888.

 

[engagarcia]

One of the problems I´ve found is that there´s no information on internet based in this kind of angles. I usually design tower structures with Mstower and PLS TOWER, and will ask them for a solution. Geometric properties has changed compared to 90º equal angles, rx and ry are axes parallel to angles members and rv is the minor principal axis. I have found some information about them, "Design Strength of Schifflerized Angle Struts" S. Madhava and M.Madugula, but is not enough to study the structures designed with this angles.
TIA/EIA 222 F-G doesn´t study this angles deeply.
Dou you know any machine to roll this angles?
Thanks

 

[transmissiontowers]

If you are a paid subscriber to the PLS-CADD yearly support, you can call tech support and find out if they know of property tables available. ASCE 10 in Examples 15 & 16, lists some references. As Cloudancer recommended, call Dave Brinker.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[Cloudancer]

RisaTower covers both Schifflerized angles and 60° bent plate in their database. Dan Horn did a very good job of detailing almost every type of tower member and configuration.

 

[engagarcia]

I have download a Demo Version of RISA Tower, and there available a data base of every kind of angles. But I´m not used in designing with this software. For example, Mstower has a function to "Schifflerize" 90º Angles, but it doesn´t check members properly by ASCE 10-97 and EIA 222-F code. I have contacted to PLS-Tower, and it´s not possible to calculate the capacity of this angles.
At the moment, there are two big problems. The first one is that I can´t find a proper software to check this structures by ASCE 10-97 code, and the second one is that i don´t know where to find this angles, or the machinery to bent 90º Equal Leg Angles.

 

[engagarcia]

I´ve found the machinery to bend 90º equal angles to 60º. It´s very old, but i need more information about it. Regarding the last post, i think the best way to check this structures is to do it manually, with the data base from MSTower or Risa Tower.

 

[hcjeffries]

engagarcia

H.C. Jeffries Tower Company, Inc., located in Porter, Texas, (

http://www.hcjeffries.com)

fabricates all types of towers, including Schifflerized angle towers. They have a Schifflerizing machine in their fabrication plant and have designed & fabricated many Schifflerized angled towers, both guyed and self supporting. They also have a CNC Angle Master in-line with the machine so they can punch holes, shear to length & punch part numbers in. They are also willing to sell angles to other fabricators. All the contact information can be found on their website.

 

[transmissiontowers]

You're in my neighborhood. I'm in Houston and Porter is just Northeast. It's good to know that these angles are available. I think we have a couple of 3 sided towers left on our microwave system, but we usually contract out the maintenance and analysis.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[MikeDB]

I use PLS TOWER and have added schiflerized angles to the data base. It seems to run fine and the answers appear to be correct.

 

[transmissiontowers]

I knew PLS Tower would handle the shape since they follow ASCE 10 very closely. You just need to get the rx, ry, and rz correct. The Area should be the same.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[MaharshiMehta]

Machine which you have put as link ( 4th June)seems to be straightening machine; if it can give shape from 90 degree to 60 degree, this will be a cold bend- which may have residual stresses on angle.
Perhaps it would be better to heat members at local position, bend it by a press with help of jig design.
I am sure all software will ( STAAD, RISA etc) will be able to handle design once properties of members are entered in data.