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  1. Motorspirit

    Seismic design of concrete bund

    Hi I hope this is the right forum for this post?? We are looking at designing a secondary containment bund for an oil storage facility using R.C panels. The site is in a seismic area and therefore it is considered prudent to check a design scenario that the bund is full during a quake (eg...
  2. Motorspirit

    Response Modification Factors - API 650 App E

    Hi All API 650 Appd E gives a table of response modification factors (for ASD methods) for use in calculating the spectral acceleration parameter. These factors account for a combination of affects including ductility, damping, overstrenth and presumably to account for the fact that ASD method...
  3. Motorspirit

    "Rules of Thumb" for Column roof tanks

    Hi All Have posted this in "storage tank" forum as well I am designing a 36m tank where the client requires a column supported roof. I am doing the preliminary layout for the roof members and wondered whether there were any industry rules of thumb for layouts that lead to efficient designs...
  4. Motorspirit

    Type of roof for Storage Tanks

    For mid range diameter tanks ( 15-25m where a self sup cone wont work) another reason for using umbrella roofs is when internal cleanliness or corrosion is an issue. eg in a caustic tank or similar where corrosion on supporting members could discolor the product.
  5. Motorspirit

    "Rules of thumb" for column roof layouts

    Hi All I am designing a 36m tank where the client requires a column supported roof. I am doing the preliminary layout for the roof members and wondered whether there were any industry rules of thumb for layouts that lead to efficient designs, ie: Max spacing between circumferential collector...
  6. Motorspirit

    Type of roof for Storage Tanks

    The type of roof chosen can be based on a number of factors, such as tank diameter,Construction costs, product stored, tank operating pressures, sensitivity of the product to internal corrosion etc. Using the diameter criteria eg: For tanks up to 10m a self supported cone could be used, 20-30m...
  7. Motorspirit

    Wind Uplift for Horizontal Tank

    API 650 wont help you much as it is for vertical tanks. For cylindrical horizontal tanks under wind loading it is really a matter of using your local loading code and determining the overturning/ sliding loads. I doubt pure uplift is a problem, however you could get uplift on one side of the...
  8. Motorspirit

    Roof Structure Finite Element Analsis of Cone AST

    Sorry, I meant for use as a service deflection criteria you should start by trying to limit the deflection to a span/250-300 range. In your case you had a 200mm deflection on a 21m span ie you have 21,000/200=105 < 250 -300 so you have potential problem. I find this range generally seems to...
  9. Motorspirit

    Roof Structure Finite Element Analsis of Cone AST

    It sounds to me as though your FEA model is too complicated and ended up giving you an erroneous result. Keep It Simple. you dont need to model the roof plate elements if it is a supported cone roof. Just model the load imposed by the roof plates. Keep you model as simple beam elements...
  10. Motorspirit

    Wind loading on low rise buildings with large openings at gable ends

    Thanks guys, some good points here. Ron is correct, we normally design structures in NZ and Aus. In parts of Aus winds are often cyclonic and hence we chose the conservitive approach. AS1170.2 has a couple of ways to deal with shielding. 1 is a multiplier to deal with near by buildings, the...
  11. Motorspirit

    Wind loading on low rise buildings with large openings at gable ends

    All We are often asked to design industrial portal frame buildings for use as loading facilities for trucks etc. Typically these are long rectangular single story buildings with gable roofs or similar. They are fully clad along the side walls and roof but fully open at both ends to allow the...
  12. Motorspirit

    what type of suppoted cone roof should I select?

    Agree with IFR here, self supported Dome would be the easiest/ tidyest For a 10m Dia tank you may even be able to get away with a stiffened cone roof with rafters only, ie no centre column. This does rely on arching action and you need to have a good kerb angle. Under API 650 this would...
  13. Motorspirit

    Tank Foundation Settlement

    You can also refer to section 7.5.2, 7.5.5 and App B of API 650. Essentially what IFRs is saying is correct. You should design and construct your foundations to limit differential settlement. If the tank settles uniformly this is not too much of a problem, provided you know what to expect, and...
  14. Motorspirit

    Attachments to Tanks

    There are some formulas in Roarks you can use to approximate but usually I find you need to model the situation in an FEA package to include the affects of the shell radius and doubler plates etc. I dont think there are any nice "deemed to comply" hand calcs out there for tank attachments but if...
  15. Motorspirit

    API 650 frangible roofs/Railings at roof/tank size

    This is not the first time Ive heard this suggestion. Firstly, as you rightly point out, for smaller diameter tanks it will be difficult to practically get your tank to meet the code requirements for frangiblity. However I always try to meet the principles where I can as ultimately, regardless...
  16. Motorspirit

    Stainless Steel Bolts in Wood Truss

    For structural purposes in salt spray environments we use A4-70 or A4-80(these are Rolls Royce) s/s bolts (tensile strengths of 700 and 800 MPa respectively . These are ISO grades but essentially are 316 cold worked bolts that have reliable strength properties Hope this helps
  17. Motorspirit

    Increasing anchor embedment depth in an existing slab

    Thanks for your input guys. The existing slab forms part of a secondary containment bund and therefore was looking to avoid cutting into it, otherwise I would definitely have gone with Mikes solution. I can still do it this way but would have to be very sure I seal it up again properly. I...
  18. Motorspirit

    Increasing anchor embedment depth in an existing slab

    Hi all I have a tank structure (with four legs) that needs to be anchored to an existing concrete slab. The chemically fixed anchors I want to use require a min embedment depth of 300mm. I can only get 200mm embedment out of the existing slab. I can pour local footings/plinths on top of the...
  19. Motorspirit

    Best Storage Tank Design Program

    I couldnt comment on which is the best, however we have found that the seismic design section of Etank is not updated regularly enough to keep up to date with the revisions of API650 APP E.
  20. Motorspirit

    Steel fibre reinforced concrete - truck slab

    Thanks guys I must admit I had approached it on the basis that the SFR would be the only reinforcement. Makes sense to reinforce conventionally and simply use the SFR for toughness etc. Cheers

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