substation bus structure using STAAD
substation bus structure using STAAD
(OP)
I am working on a single-phase bus support for a substation. I am trying to model the insulator in STAAD. The insulator is made of porcelain material and rest on top of a HSS column. What is the best the best way to model the insulator in STAAD so that the loads for the bus items sitting on top of the insulator are transferred to the HSS column. What type of member should be used for the insulator? Should the insulator be treated as a dummy member? Any suggestions/comments are appreciated.






RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
I remember everybody that saw the STAAD files immediately saw the "weird" member and flagged it. I'm searching old STAAD files now.
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
http://files.engineering.com/getfile.aspx?folder=3...
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
No offense, but substation steel design (IMO) isn't about getting the most precise answer to your problem. It's about developing a reliable, repeatable, constructable design. Way better to use a standard robust detail than it is to save 2lb/ft on a beam.
Besides, you are likely overestimating your knowledge/modeling of how each individual structure's foundation will behave anyway. For a bus support, you're probably on a bunch of individual drilled shaft foundations -- they're each going to settle and rotate differently from the next. That's likely going to affect your design as much as the properties of an insulator.
Is this really a single column bus support? Why bother with STAAD? Design it by hand and be done.
(All of the above comments assume that you don't need a specific dynamic analysis. And I mean really need -- it'd have to be a complicated substation retrofit or a high seismic zone with substantial space constraints before I'd get to the level of properly modeling insulator behavior.)
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
I answered this question in the Transmission Structure Engineering forum but it seems like I am about the only one that posts there. If you have a copy of ASCE 113, read over the design sections. IEEE 605 also has info on bus design. We are revising ASCE 113 and it should be published in a year or 2. It is tough to get 30 structural engineers from all over the country to agree on anything.
http://www.eng-tips.com/viewthread.cfm?qid=402289
If you are trying to do a full dynamic analysis of the bus support for a short circuit event, you will need the forcing function from the EE's. From what I have seen and done for many years in the business, you use IEEE 605 or ASCE 113 to get the SC loading as a static equivalent load and combine it with the wind or ice load or whatever the substation owner wants you to consider, then design the column and base plate. If all 3 phases are on the same column, the SC forces cancel out on the support beam. The phase spacing on voltages above 345kV is so large, you get individual columns for each phase.
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I have been called "A storehouse of worthless information" many times.
RE: substation bus structure using STAAD
I am also working on base plate design for bus support structures. I am designing moment resisting base plates for HSS square columns. I am having some issues. I am aware of using 0.95 times the depth and width to determine m and n. The issue that I am having is with designing the base plate without it being supported by grout/concrete. The base plate is on leveling nuts. Based on everything I find in AISC design guide examples, all of the base plates are resting on concrete and all of the formulas are based on the base plate resisting on concrete to determine bearing pressure.
Would any one happen to know how to design the base plate without it being supported on concrete? I have designed base plates in the past for other structures in another industry, but all of them rested on concrete/grout. ASCE 113 mentions the design on base plates and the formulas given do not mention concrete strengths.The main issue I am having with the ASCE 113 formulas is the calculation of beff value. My base plate is a square with 4 anchor bolts. The center to center bolt distances are equal. Does AISC have any provisions for base plate that are not supported by concrete? What is the substation industry standard method for designing base plates? See link http://files.engineering.com/getfile.aspx?folder=0... for example sketch. Any suggestions/comments are appreciated.
RE: substation bus structure using STAAD
Don't forget the diagonal cuts through the baseplate at the 4 bolt holes in the corners.
RE: substation bus structure using STAAD
I also recall that ASCE 113 is the right reference for baseplates without grout, but I left my references drive at home today. In short, you'll solve for a force distribution among your bolts using statics, then check the steel baseplate for point loads at bolt locations along straight failure planes (similar to a concrete footing). Often times a 45* failure plane that captures the most heavily loaded bolt (usually based on lateral load at a 45* angle) will govern.
Also, if you're using oversized holes to allow for some anchor bolt placement tolerance (typically a good idea), take that into consideration for distribution of base shear in your bolts. You probably can't count on all of the bolts bearing against the base plate simultaneously unless you tell the contractor to go back and field weld an oversized washer over each bolt. Usually it is easier to just assume the base shear only gets carried by some proportion (half?) of your anchor bolts.
RE: substation bus structure using STAAD
Our industry is somewhat unique in that we are willing to accept some structural failures in the quest for lighter structures. The building and bridge guys OTOH, are not allowed the same latitude. A building collapse or bridge failure is not acceptable under anything other than a 5000 year extreme event. If one of my towers or substation bus structures falls down, you can't charge your smartphone for a few hours or days.
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I have been called "A storehouse of worthless information" many times.
RE: substation bus structure using STAAD
RE: substation bus structure using STAAD
@transmissiontowers
I appreciate your information regarding the design of the base plate. Especially the information you posted at thread181-27567 ( http://www.eng-tips.com/viewthread.cfm?qid=402289 ). Do you h--ave any knowledge of designing stiffener plates for base plates? I do not see any info regarding the addition of stiffener plates to the column to help reduce the thickness of the base plate in ASCE 113 and ASCE 48-11. Would you happen to have a design example? Please let me know if you have any recommendations for stiffener added to base plate design.
RE: substation bus structure using STAAD
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I have been called "A storehouse of worthless information" many times.
RE: substation bus structure using STAAD
Thank you for your response regarding the stiffener plates. In regards to your method of calculating the bend line for the base plate design, what is your method for determining the tangential bend line length & the distance of the anchor bolt center to the tangential bend line (in ASCE 113 this dimension is designated as ci). I understand the method you used for the parallel bend line. I am trying to determine which bend line (the parallel or the tangential) provides the best base plate design for my hand calculation. Do you subtract subtract the width of the HSS from tangential bend line to account for the galvanizing drain. Please see link for my sketch http://files.engineering.com/getfile.aspx?folder=4... . Here is another document which mentions the tangential bend line http://files.engineering.com/getfile.aspx?folder=0... ,you can see the information much better on this figure when you zoom in (I initially had issues see the words). Here is a copy of ASCE 113 http://files.engineering.com/getfile.aspx?folder=4... . Any recommendations are greatly appreciated.
RE: substation bus structure using STAAD
Your PLS-POLE reference is more for 8, 12, or 16 sided T-Line poles where they consider bending only along a flat and not tangent to a vertex. Their equations come from ASCE 48-2011.
From ASCE 113 section 6.8 (I wrote some of it about numbers of bolts and the plate thickness, but was talking about big dead end poles with 20 to 48 bolts). Look at Figure 6-1a and check the bend lines 1-1, 2-2, and 3-3. If the hole in the plate is the same size as the HSS tube, you have to subtract the tube width from the effective bend lines 1-1 and 2-2. Choose the maximum bolt load for 3-3 and do the thickness calculation for all bend lines and pick the thickest plate.
There is a paper by a guy named Horn about pole baseplate design that is around 100 pages. Do a search for Daniel Horn and a paper called Technical Manual monopole bases. I found a copy at www.towernx.com that you can download. I believe he was in the telecom world and did large monopole base plates but the concept is the same.
Good luck.
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I have been called "A storehouse of worthless information" many times.