ASCE 113 Update 3

[799931]

Hello transmissiontowers, I was just checking in to see if we might get an updated ASCE 113 this year.

I copied a reply from an old thread below since they closed it:

We have a meeting in Feb 2018 to look over committee comments and after that we have a spot on the agenda of the ETS conference in November to give a status update at the pre-conference. After that we will send to peer review and then address the peer comments we get back. Probably sometime in 2019 to go to publication. Lots of loose ends to fix. I know ASCE has been after us to finish, but getting 25 Structural Engineers from all over the country to agree to technical details is like hearding cats.

Thanks!

 

[StructureME]

Dauwerda - I've used those, specifically the strut and tie paper you linked. They are useful, but I suppose the question remains how to treat round ties as supplemental shear reinforcement. IMO, the shear ties confine the concrete cone from breaking out, but I still haven't found a good reference on exactly how much of the time can be considered "developed" since it's round. This is something heavily debated in our structural department, so other opinions are graciously appreciated!

I'm new to eng-tips, so sorry if this is now digressing from the original post.

 

[transmissiontowers]

StructureME;
I don't do foundation design (I always tell people I proudly put my mistakes up in the air for all to see as opposed to the foundation people who bury their mistakes) and am unfamiliar with 318 but I gather you are trying to size the hoops or spirals or ties for the shear reinforcement of the drilled pier. The 1st edition of 113 (I was Vice-Chair on that one) in section 7.3.3 and Figure 7-6 talks about ACI 318 and the development length of the vertical rebar and the use of smooth and deformed bar anchor bolts and how much development length you need.

On the ASCE 7-16 question, point your clients to the part that exempts T-Lines and let them know IEEE C2 is a national standard with maps done for our industry plus the new edition of ASCE 74 which uses maps from 7-16. For substations, 113 is just a MOP but we do use the maps from 7-05 for the 1st edition and the 2nd edition coming out will use 7-16 maps.

Early next year we will install a big 220' T-Line pole with 100 #18 anchor bolts in a double cage, 15'-0 diameter drilled pier (14'-0 diameter cage of #18 rebar), 60'-0 deep. IIRC, the ties are #6's and I think they are 4" spacing where the anchor bolts are up in the cage. The contractor says they can drill a 16'-0 hole 100 feet deep if we need that much of a foundation.

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

 

[StructureME]

Transmissiontowers, that's actually another debated opinion in our group; the exemption in ASCE for transmission and whether or not it applies to substation structures and foundations. I believe the exemption does apply for wire supporting tline towers, but not necessarily heavy 1million lb transformers on foundations, control buildings, or switch stands inside the yard. I think for now, until the newer ASCE 113 comes out, we'll likely stick with whatever building code governs the state, and NESC for wire supporting structures that tie into our substations just outside the fence. If the state uses a building code corresponding to ASCE 7-05, I think it's appropriate to use ASCE 113.

And holy cr*p that's a big foundation! Must have massive tensions on those wires!

 

[transmissiontowers]

I get your point on the NESC inside the fence. The new 113 was very careful not to use the term "building" when describing that function and started using Control Enclosure to describe the spot in the yard where the control cables are located. We did not want to have a local building official require ADA ramps and bathrooms inside our substation fence. We did not want to get into the structural design of the Control Enclosure.

This is the statement we now have:
"Control enclosures contain the switchboard panels, relaying and controls, batteries, battery chargers and other equipment for metering and communications. Control enclosures may be designed by the supplier as part of the equipment contained within, or by using rules similar to non-building structures. Control enclosures are not covered in this document."

We are also working on an Appendix (like the one in ASCE 74)as a Pre-Draft Standard for what the MOP would possibly look like if it were advanced to an ASCE Standard and to gather comments from users. A few years after the 2nd edition of 113 comes out, the next step would be a new committee to create the ASCE Substation Structures Design Standard XX, which would have the wind, ice, and seismic maps and all the design equations or point to the document where they are located like the AISC Manual.

The big pole is a 30° double circuit vertical 345 crossing over a road or another 138 circuit. Three 959 ACSS wires per phase with a full dead end capability on both circuits so we terminate 18 wires with a RBS of about 33 kips each plus a couple of OPGW wires.

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

 

[799931]

Hello transmissiontowers,

Any chance the updated version of ASCE 113 has made it to peer review?

 

[transmissiontowers]

We are getting closer but have not sent it to peer review yet. All chapters are mostly done with some grammar checking to finalize. The big hurtle will be the examples Appendix which has been worked on but needs to be put into DOCX format from Mathcad. The ASCE publishers want all equations in Word Equation Editor and most of the chapters are already done but a few remain. Once all the Chapters are done, we need to work on the Appendix for the Pre-Draft Standard. The initial thought was to wait a few years to get comments on the Standard idea and then start on it. The thought now is as soon as the 2nd edition is published, a new Committee will be formed to tackle making 113 into a Standard.

One friend on the committee attended a Webex on ASCE 7-2022 and there will be a new section on Tornado Loading on buildings and other structures in 2022. Basically from El Paso to the tip of Maine will have to consider Tornado loads. The though process is, if we have a Loading Standard for T-Lines (ASCE 74 as a Standard) and ASCE 113 as a Standard for substation loads and design, we can fight off the Building guys that want us to use ASCE 7-22.

I have tried to point out when the bean counters come around to try to reduce substation costs, that reducing the cost of substation structures by reducing overload factors is not very safe and not cost effective. If the cost of the steel in the substation was free, the overall cost of the land and wire and equipment combined would still be 85 to 90% of the total substation cost. The labor to build the substation would still be there. Talk to the provider of the 2 million pound auto-transformer and negotiate a 10% cost reduction if you want to save money.

I had one EE manager come ask me if I could remove all the lacing in the bottom 20' of all the lattice towers to prevent people from climbing them. Obviously the EE's did not study L/r. I told him we could if he did not mind the tower line falling over in a 10 MPH wind. The tangents might stand up for a while but the angle towers and dead ends would fall over as soon as the last bolt was removed.

Sorry for the long and rambling answer, but I've been working from home for almost a year in my home office.

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

 

[StructureME]

@transmissiontowers,
Thanks for the update, I completely agree with cutting substation costs! Stop complaining about using a W12 column when the circuit breakers cost 10X the value!! I just got done analyzing a huge lattice structure in California, only to hear the client complain "well it's been standing 50 years so I disagree with your assessment of member failures!" Unfortunately, it's hard to talk to a non-structural person about wind MRI's and single angle compression...

Side question: how can one join ASCE 113 committee?

 

[transmissiontowers]

The bane of the structural engineer is every kid that ever built a tree house (do they still do that?). Sure, you can come up with anecdotal evidence that this or that structure has been around for 30 years so if we add double the wind load and triple the weight, it should be fine.

You can build a simple structure that will stand up when there is no wind, but we have to deal with a 100 year event. I had a friend build a metal storage shed in his backyard. He had the walls up when a wind came and he was chasing it around the yard and it was almost destroyed before he could attach it to the bottom and get the roof on it.

One telecom guy wanted to put a MW Dish on a concrete pole mounted at 85'-0 AGL so he said he needed a 85'-0 tall pole. I told him he would need at least a 100' long pole and maybe more depending on the soil and the size of the dish. He says, well it only weighs 150 pounds, so any old pole would work. I told him that if he wanted it to stand up to a 10 mph wind, maybe any old pole would work, but in a 140 mph hurricane wind, a bigger pole would have to be used because you are putting a big sail on top of a flexible pole and the dish may not be pointing at the target when the hurricane blows in. What good is a MW Dish that looses communication when the wind blows over 40 mph?

Off my soap box.

The Current ASCE 113 committee is wrapping up, so no new members are being accepted. When it is published, there will be a new effort to move it to a Standard like ASCE 48 or ASCE 10. The just published ASCE 74, is moving to be a Standard and you can inquire about getting in on that effort. The original thought was that ASCE 74, 4th Edition (which has a Draft Pre-Standard Appendix) would be left out in the public to gather comments and in a few years, it would be ready to be elevated to a Standard. The current thinking is to go to the Standard soon to stave off the calls for us to abide by ASCE 7 loading. T-Lines are not buildings where loss of human life has to be considered, although in my part of Texas several people died last week trying to stay warm without electricity. Mostly from carbon monoxide using charcoal grills inside the house or a gasoline generator inside the garage.

When 113 is done, ASCE will want a new Committee to advance 113 to be a Standard. Just changing a few could's to shall's will not be enough. It will be a huge effort and I will suggest that they get an expert in MS Word to help with the effort. I am learning more about Word and Tracking Changes but citing references and keeping track of section 6.3.1.2.7.3 when it was moved and adding 3 equations before Equation (6-4) and renumbering everything between (6-4) and (6-42) and finding the places in other Chapters that refer to the old Equation 6-41 that became Equation 6-44 is a giant task. For those that have read this far, look up the free Agent Ransack program that searches Word DOCX files in multiple folders for text so you can see where Section 6.3.1 is called out.

Another Word Tip. Copy your DOCX file and rename it with a ZIP extension and look inside the ZIP file to find the pictures and figures that are JPG, PNG, or TIF if you lost the original file that was inserted.

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