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  1. pikku14

    Midas Civil Recommendations

    Midas is powerful, but my recommendation is to skip over the wizard. Like all in-built wizards, it's really geared up for a very specific arrangement. For the majority of structures that don't fit that template exactly, I'd be completing the model outside of the wizard - all of what you...
  2. pikku14

    Field splice of girder with different web thicknesses

    In my part of the world we cater for variation in prestressed girder hogs by estimating and documenting at various time intervals (transfer, 30, 60, 90 days typically). The surveyors and site team then can compare what's actually achieved in the precast yard and prior to erection and adjust...
  3. pikku14

    load rating - loads other than dead and live

    Not sure on what your contract or typical load rating set-up is in the US, but something I've done in the past to enable planning (for e.g. is there need to strengthen/replace) is to simply define a utilisation of elements such as the substructure where lateral effects have a significant effect...
  4. pikku14

    how much above "capacity" you feel comfortable going over?

    My .02: It depends on the situation. How likely is the load/combination of loads to occur? How refined has the analysis been? How are the construction practices/oversight? And also: how will it fail? Is it a ductile failure that will give warning, and the system has capacity to handle the...
  5. pikku14

    Bridge Abutment Pile assumptions - MSE wall

    Is your company/team designing the MSE wall or is it being done by a contractor? I'ts fairly common to isolate the piles within the MSE wall to avoid loading the MSE wall due to actions on the bridge. If you're not isolating your piles, then you'll need to ensure the MSE wall design has...
  6. pikku14

    Performance based design of a bridge pier for a train collision event ?

    Hey Structural Thumb, to put it quite bluntly, I think this is a really bad idea. Practically from a structural design perspective, the magnitude of load of a train collision gets very high, very quickly. The loads provided in the codes tends to be for a 'glancing impact' happening at an angle...
  7. pikku14

    External Tendons on Curved Bridges

    It's really dependent on the radius of your curve,where your deviators are and how much prestress you require, whether you have the space to anchor in each span or need to provide continuity across the pier segments. There'll be a horizontal component of the force to consider in the design, but...
  8. pikku14

    Strut and tie bottle bursting stress?

    Agreed 3600 (and now the new 5100) isn't very clear on bursting reinforcement requirements for large members. You're correct that if the load can spread, it will, especially so at SLS and will tend towards a prismatic load path at ULS I'm trying to dig up a resource which specifically spoke...
  9. pikku14

    Box Beam Internal Diaphragm

    Distortion will cause havoc with a steel box without regularly spaced diaphragms (although usually these are K-braces for the typical composite steel-concrete boxes.) And then plate diaphragms at bearing locations as BridgeEI mentioned. For anyone interested, Hambly's got a good section...
  10. pikku14

    midasCivil Software for bridge design

    I've used it quite extensively. My thoughts are that it is a very powerful piece of software, but it's still got teething problems (particularly with the moving loads.) It can be a little un-user friendly at times as well What sort of bridges are you intending to design? I used midas for...
  11. pikku14

    Screed Elevation Diagram

    We often provide deck screed diagrams in Australia. It's just a simple diagram showing the deflection (typically at 1/4span intervals) to allow the contractor to adjust the levels allowing for deflection due to the deck slab pour/(s). Not sure if that's exactly what you're after
  12. pikku14

    choosing the best system and construction sequence of integral pre-stressed bridges

    I'd recommend you have a read of Robert Benaim's book "design of prestressed concrete bridges". Side note: you could also likely remove the third web for a box of that width. the top slab may have to be slightly thicker but that usually works out to be more economical
  13. pikku14

    Initial and effective prestress

    I'm not familiar with the software but is there a detailed output? or does it just spit out a few key answers? Likely to be an error in inputting some of the design parameters. Check loads, properties, creep & shrinkage parameters etc.
  14. pikku14

    Heat of Hydration of Mass Concrete

    Get your hands on a copy of Ciria C660. Covers temperature rise/fall and differentials in a lot of depth The 20 deg is a temperature differential value above which cracking will occur in thick members due to internal restraint. In your case you also have external restraint due to it being...
  15. pikku14

    Soil spring stiffness

    I'd recommend having a read of this presentation which has some really good practical tips on using soil springs: http://australiangeomechanics.org/pdf/20130814-UseAndAbuseOfSpringsToModelFoundations.pdf KootK: Yeah I think it would. The 400kPa is the "real" value, although I've always varied...
  16. pikku14

    Shear Friction: Where and When?

    I think that the situation illustrated in this slide would be a case to check shear friction with monolithic concrete http://files.engineering.com/getfile.aspx?folder=041fe9b6-dfa5-4194-a075-e689c5c88449&file=Detailing.pdf
  17. pikku14

    Cross-Frame Design Questions!!!

    Gwynn/RHTPE, Interesting comments Are most contracts design only in the US? Down under there's a lot more Design and Construct or Alliance projects so the designers have to work closely with the contractor and account for their construction methods etc. (well that's how it's supposed to work...
  18. pikku14

    Spread Footing Extension Due to Column Eccentricity

    KootK, I was looking through the Hilti document you attached and was wondering if you knew why the minimum anchorage length is greater for a bar in compression than tension? (See page 6) Cheers
  19. pikku14

    Vortex Shedding in Eurocode

    The ratio to be used is the length/height to the diameter so 150/13.2 or 150/3.6 both of which > 6, therefore vortex shedding should be investigated
  20. pikku14

    Keeping drain pipes.... draining.

    Coming at it from a different angle: the other option if feasible/acceptable, is to restrict the flow width within the shoulder and collect using off-structure drainage

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