Entering the Transmission Tower Industry

[dhoward26]

I was recently approached by a company and asked if I do transmission tower design. I have never done one, nor do I really know where to start. I have been to the Power Line Systems website and looked at all of their programs...they seem to be the leading company for modeling in the industry.

Questions:

1) Would I be getting in over my head with this as I am a one man shop?
2) What does the PLS modeling provide? FE analysis obviously, but does it design member sizes & connections for you as well? Or do you have to input the member sizes and then details the connections?
3) How large of a learning curve would there be to enter this world of structural engineering?

I would not, however, do this without review/mentor-ship from someone who has been in this field for quite a while...too much liability. Would I be best off taking the project and sub-contracting it out to a different company?

Thank you for your help.

 

[transmissiontowers]

I've been doing modeling in PLS-Tower for my utility company since the late 1980's so I have lots of experience. I have analyzed towers since the 1970's before PLS came out.

1) It takes a lot of reading of ASCE 10 to understand towers and how they are modeled and designed. I'm not up on the latest price list, but you will have to buy PLS-Tower and probably PLS-CADD Lite if you don't own a copy. I believe the cost is around $25,000, IIRC. You will need to attend a Tower class at PLS-CADD.

2) The models are not too hard to do with lots of graphical input and automatic symmetry, but the industry is very specialized. I would guess there are less than 1000 engineers worldwide that design towers. If you are near Columbus, Ohio next week there will be about 600 of them attending an ASCE conference. The program has member size inputs and number of bolts and number of holes out. There is a Tension allowable and Compression allowable for the member plus a bolt shear allowable and a bolt bearing allowable for each member that is calculated and compared to the actual load in each member in the tower. Once you decide on a geometry and have it input, the program will make several passes and design all the members. There are things like Tension only members that buckle out when compression happens. The program has a non-linear analysis engine that is at the heart of the program and it will handle guyed towers as well as EIA/TIA towers.

3) I would say the learning curve is pretty steep because nobody in their right mind puts single angles in compression braced with redundants to the lacing which can buckle.

I will relate a story about an engineer that lost his small company trying to do Transmission Towers. Way back in the 1980's before PLS, there was a down turn in the petro chem industry and this small 2 man firm was looking for work. They took on a T-Line tower design job. They had done pipe racks and other industrial frames. They signed a penalty clause where the client could reduce payment if the small firm was late on delivering the drawings for the tower. They were using STAAD and had a tough time doing the model because the tower base slopes out in 2 directions and nothing is square below the bend line. They finally got a design done and had to draw up all the details of the members and they had no clue how to do it. Deadlines passed, penalties mounted until they were doing the tower for almost free. It got so bad they declared bankruptcy and closed the business. When I met the engineer, he was working in our Utility's Power-Plant group designing pipe racks using Staad and said he appreciated the knowledge it took to design towers after trying one.

Sorry for the long dissertation, but come to Columbus next week and talk to the experts. The PLS-CADD developers will be there and can show you their products.

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

 

[MiketheEngineer]

IMHO - find something more lucrative!!

 

[msquared48]

I entered this market about 6 months ago on the cell side of the market as opposed to the electrical transmission side, and it is very competitive, as well as interesting, atleast to me.

I use TnxTower a lot (Used to be RISA Tower). There is a learning curve, even after the 45 years or so I have in my pocket, and I am still learning.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[transmissiontowers]

Maybe we scared the OP off? There were over 1000 attendees at the conference and lots of good presentations although 20 minutes is a short time to show any depth.

The tower industry is a very specialized field. I analyze a few free standing M/W towers we have on our system and the EIA/TIA is a little hard to understand after many years in the utility side.

MMcC; Good luck in the business and keep learning. I get the M squared in your handle but the 48 must be your birth year?

Back on topic. We are going to face a big question in the near future on what wind maps to use in our industry. Up until now, we used the ASCE 7 wind maps for 50 year MRI. The ASCE 7-2010 version of the maps are way different and our NESC, ASCE 74, ASCE 113 ( I chair this committee) will have to decide if we use ASCE 7 maps. I'm not sure what EIA/TIA will do for a wind map.

Our industry has resisted being called "critical" up till now. 50 years ago being without power was an inconvenience and you lost the 2 days worth of food in the freezer. Today, you can't charge your iPhone, iPad, iDevice and you can't instantaneously find out the thoughts of some Hollywood celeb on twitter or check the 500 eMail messages you got today.

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