ASCE 113 Update
ASCE 113 Update
(OP)
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!
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!
RE: ASCE 113 Update
His response was,
RE: ASCE 113 Update
RE: ASCE 113 Update
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
RE: ASCE 113 Update
RE: ASCE 113 Update
We had our Houston meeting and are trying to speed things along. To joshab; We have gone to ASCE 7-16 wind maps and have a couple of tables for load combinations. We have one for LRFD load combos and another for ASD loads. We recommend LRFD for most structures, but recognize ASD should be used for deflection cases and probably for foundation design. Deflection cases are done for less than extreme wind loads (if you want). Of course, you can check deflection at 140 mph if you want to, but realistically you probably want to check for winds where the equipment might be expected to operate like a disconnect switch. We have greatly expanded SCF equations and given the option for doing a full dynamic analysis (if you have the time and data) of a SCF case with forcing functions. Normally, we just use IEEE 605 type equations and use the max static load and combine with extreme wind or extreme ice. The simple steady state equation is given for those that wish to use it. The left coast guys have expanded the seismic equations and you have the option to do a full dynamic analysis of seismic cases. One key point is that even though we give load combinations and suggested factors, you do not have to consider every load. You probably do not need to combine a hurricane wind with SCF and a seismic load with an ice storm and do a full dynamic ANSYS run to find the force in a beam or column. Anchor bolt design has been revised for the case where the base plate is on leveling nuts.
To dauwerda; Once the committee has edited the chapters, we will select a few people to do a peer review and combine all the chapters into one PDF. Since we are still a Manual of Practice, there is no public comment phase. Once the peer reviewers return their review comments and suggest changes if any, we will vote as a committee for each change and if it should be done or not. The first edition of 113 had over 1000 comments and changes requested. Many were just grammatical, and some were substantial and we adopted most but not all.
One thing that we are trying to include is an Appendix for a Proposed Draft Pre-Standard of what 113 might look like if it were to become a Standard. I believe ASCE 74 did the same. The Appendix is just to get comments from users on how they like or dislike it.
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
RE: ASCE 113 Update
I'll logon to my work PC and look into the factor question since I don't remember off the top of my head, but in general when you compare 113 or 74 or other T-Line ASCE documents, we generally do not have the loss of human life as a factor in our documents. ASCE 7 has to consider the building or bridge as a potential loss of life category. A substation structure or T-Line tower is less critical than a building and we use lower factors. There is a lot of research behind the wind and ice maps in ASCE 7 but they sometimes include factors that the T-Line industry does not use.
Electricity is becoming more important as technology depends on it and we may get to a point where regulators dictate that we use bigger factors to prevent wide blackouts. All it will take is for some US Senator's child not to be able to post a picture of their latest meal on Facebook or Insta-Whatever in a blackout, and we will be designing structures for a 3000 year return period wind storm that coincides with a 7000 year return period earthquake and a Short Circuit event with 3 inches of radial ice.
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
Table 3-18 Ultimate Strength Design (USD) Load Combinations
CASE COMBINATIONS (all 8 cases may not apply)
1a 1.1 D+1.0 W_300+0.75 SC+1.1 T_(WI-300)
2a 1.1 D+1.0 I_100+1.0 W_(WI-100)+0.75 SC+1.1 T_(WI-100)
3 1.1 D+1.0 SC+1.1 T_APP
4a 1.1 D+1.0 E+0.75 SC+1.1 T_EA
5a 0.9 D+1.0 W_300+0.75 SC+1.1 T_(WI-300)
6a 0.9 D+1.0 I_100+1.0 W_(WI-100)+0.75 SC+1.1 T_(WI-100)
7 0.9 D+1.0 SC+1.1 T_APP
8a 0.9 D+1.0 E+0.75 SC+1.1 T_EA
a The combination of SC loads with extreme events listed above should be determined by The Owner
Table 3-18 and Table 3-19 show suggested design load cases, combinations, and minimum load factors to be use for substation structures. For the load conditions that include ice, the effect of icing on the wire dead load and wind load concurrent with the ice formation should be included. The individual load components are the following:
D = Structure and equipment dead load;
W_300 = Extreme wind load (F, from Equation 3-1,) from 300yr MRI wind map;
I_100 = Extreme ice load from 100yr MRI Ice Map;
W_(WI-100) = Concurrent Wind load in combination with ice from the 100yr MRI ice map;
T_(WI-100) = wire tension resulting from the following loads acting simultaneously: weight of the wire; weight of ice corresponding to ice thickness in the 100yr MRI ice map; wind load on the iced wire corresponding to wind speed in the 100 MRI ice map and: wire temperature per Figure 3-3a through Figure 3-3e.
E = Seismic load as defined in Section 3.1.7.8;
T_(W-300)= wire tension due to wire weight acting simultaneously with the wind force corresponding to the wind speed from the 300yr MRI wind map at an ambient temperature determined by the Substation Owner;
SC = short circuit load;
T_APP = wire tension due to the wire weight acting simultaneously with any appropriate ice weight and temperature as determined by the Substation Owner (every day or normal operational conditions);
• T_EA= wire tension corresponding to wire dead load acting simultaneously with the seismic loading per Section 3.1.7.13, at an ambient temperature determined by the Substation Owner
The above text is very preliminary and subject to peer review and could change before it gets published but it is the current thinking of the Committee.
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
RE: ASCE 113 Update
Hopefully, sometime in 2020 will get it to ASCE.
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
I am currently reading ASCE 74-20, and well, many things change, I think for the good.
We are now reaching the end of 2020. Any news on the process for ASCE 113?
RE: ASCE 113 Update
I have gotten a PDF of ASCE 74 but have not gotten around to reading over it yet. IIRC, their wind maps are the same as 113's but the big change for my part of Texas is the hurricane prone regions are now in Exposure D according to ASCE 7-16 (we used to be in Exp C)
My other observation is the NESC-C2 that covers all things on T-Lines, still uses the wind maps from ASCE 7-05 and the NESC is very slow to change. The dilemma is, do I abide by NESC (not a design code, but a public safety code) or do I use MoP 74 and their wind maps?
I have a friend in Louisiana that was asked what the cost impact would be to design poles and towers for a 170 mph wind vs the 140 mph wind in the NESC (about a 50% increase in loads) because all the T-Lines went down in the hurricanes that hit them this season.
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
RE: ASCE 113 Update
The owner of the T-Line or Substation decides which codes to follow with input from the engineers. Historically the NESC with OLF's >1 on Rule 250C wind maps has served well in my Utility with few T-Line and Substation structure failures during hurricane events. IIRC, there is an exemption in 7-16 for electric utilities because we do have NESC and ASCE 74 to use for wind maps. Electric power is becoming a "can't do without" commodity and might get the attention of the regulators that could force us to be a Risk Category IV for new designs.
AFA the foundation, yes we will have a chapter on them but it is very generic to say what are the general types of foundations in a Sub. There are no equations in the chapter for what the capacity of a foundation is. We do have load combination tables to use with the foundation that are based on ASD. I do not do foundations myself and have always used a USD approach for the steel design, so designing foundations is very foreign to me. As long as you tell the Geotech the reactions and the OLF's that are included in them, they should be able to come up with a foundation that will withstand the ultimate loads.
On the anchor "rods", there is a new method based on a European ETAG code but the big change is for the base plate on levelling nuts, you will always have to include the bending moment in the bolt. ASCE 48 allows you to neglect the bending if the the gap is less than 2 bolt diameters, but 113 recommends to always use the bending, no matter the gap.
HTH
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
The ASCE 7-16 applies to buildings and other inhabited structures. NESC C2-2017 recognizes that transmission lines, distribution lines, and substation structures are uninhabited in extreme events. ASCE 7-16 has a section in the previous edition ASCE 7-10 on Page 506, Section C26.1.2 Wind, where the electric utility industry has an exemption from the wind maps. I believe it is because we have developed a loading guide, ASCE 74, that applies to our structures plus the NESC.
These are my opinions and may not hold up in court. :)
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I have been called "A storehouse of worthless information" many times.
RE: ASCE 113 Update
Thanks again!
RE: ASCE 113 Update
https://www.semanticscholar.org/paper/Design-of-An...
Another resource is ASCE's "Anchorage Design for Petrochemical Facilities"
https://ascelibrary.org/doi/book/10.1061/978078441...
Unfortunately these do not address round piers, but I believe engineering judgement can be use to apply the same principals.
RE: ASCE 113 Update
I'm new to eng-tips, so sorry if this is now digressing from the original post.
RE: ASCE 113 Update
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.
RE: ASCE 113 Update
And holy cr*p that's a big foundation! Must have massive tensions on those wires!
RE: ASCE 113 Update
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.
RE: ASCE 113 Update
Any chance the updated version of ASCE 113 has made it to peer review?
RE: ASCE 113 Update
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.
RE: ASCE 113 Update
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?
RE: ASCE 113 Update
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.