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  1. ukbridge

    Book on debugging FE model, do you know any?

    Generally speaking the software support team should provide input over the phone/email for unusual problems like these - its what we pay them a very fair wage for at the end of the day.
  2. ukbridge

    Distribution factor Bridges with multiple girder types

    Use a grillage model.
  3. ukbridge

    Secondary Effects on Integral Bridges

    From experience, the behaviour of the bridge will be quite sensitive to the EI of the piers. In simple terms, make sure you use an appropriate long-term modulus for the piers for SDL, soil ratcheting earth pressures etc. Its not an exact science at the end of the day, play around with the E in...
  4. ukbridge

    Plastic Section Modulus Calculator

    https://pdfs.semanticscholar.org/14d6/f9c2d195c541d855a5789e22022393a09744.pdf This paper gives a method for a (simple) spreadsheet implementation which I've used in the past.
  5. ukbridge

    Unbraced length of Top Flange in Steel Tub Girders

    Word of warning, from UK perspective it is very common to use plan bracing for Open Tub box girder sections even if you can justify it from a ULS perspective the second-order deformations and rotations can be significant...
  6. ukbridge

    Learning FEA

    Despite being an avid self-learner, there's really no experience for working in a consultancy from a talented senior engineer. After all you can't become the worlds best racecar driver through reading a few mechanical engineering textbooks.
  7. ukbridge

    RSA_Piles rotation

    There's not enough information to understand why the rotation is so large, some diagrams showing rotation and a deflected shape would be useful. In general I don't like using "infinitely stiff" supports at pile bases, use springs instead for the pile vertical and horizontal stiffnesses. Even...
  8. ukbridge

    Elastic Resistance to Lateral Buckling (Appendix H - 3404)

    No worries - one other thing that gets often forgotten, dont provide full lateral restraints at the end of the BEF model as this will overestimate the buckling load factors you calculate. Make sure theyre springs not fixed supports.
  9. ukbridge

    Any convention for specifying spacing of metric bars in slabs?

    Increments of 25mm, 98% of the time I always use a 150mm spacing unless its for beams when I'd specify the number of bars in a face instead.
  10. ukbridge

    Elastic Resistance to Lateral Buckling (Appendix H - 3404)

    Agree with everything Agent says If you don't do an eigenvalue buckling analysis, you need to use the BEF method and model the top chord as a beam on springs representing the U-Frame stiffness of the diagonals (I'm assuming theres no plan bracing). EN 1993-2 has a method of doing this, or you...
  11. ukbridge

    Estimate stiffness/drift in a steel moment frame

    I think I can now remember the method. Basically work out the inertia of the column group (i.e. Sum of Ah2 where A is the column area, and h is the distance from the column group centroid to the centre of the column.) Using PL^3/3EI for the bending deflection, and WL/AG for the shear...
  12. ukbridge

    Postbuckling - meaning of LPF vs displacement plots

    I agree with ESPcomposites in terms of observing the global behaviour rather than a single node. Also I agree the way in which you applied the perturbing mode might be a problem - a good software package should allow you to use the scaled deformed mesh of the eigenmode shape which should give...
  13. ukbridge

    Postbuckling - meaning of LPF vs displacement plots

    When you say "linear buckling" does that include allowances for geometric imperfections i.e. using the Perry-Robertston buckling curves? Or is "424870" simply your Pcr? Physically the graph looks more "correct" to me. I'm not sure about your material properties: 1. 200MPa sounds quite low to...
  14. ukbridge

    Estimate stiffness/drift in a steel moment frame

    IIRC theres a method described in Iain MacLeods book "Modern Structural Analysis" that treats the moment frame as an equivelant cantilever based on the number of bays - you can then calculate dx based on PL3/48EI using the value of EI you work out using the method.
  15. ukbridge

    And What's This?

    Theres tons of these for lawyers/solicitors as well - afaik all massive scams.
  16. ukbridge

    Postbuckling - meaning of LPF vs displacement plots

    Hi FEA way, Its hard for me to say without looking at the model. Its up to you to understand whether the graph "looks right" or not. To me, it does not - the transition from geometrically linear to nonlinear behaviour is very sudden and on a feel basis is not right to me. The graph says to...
  17. ukbridge

    Postbuckling - meaning of LPF vs displacement plots

    Im not really familiar with that type of structure but the graph doesn't look right to me. A lot of the time these types of analysis require sitting down with the model and interrogating it but here are some tips: 1. It seems to me that the solution has failed to converge on a "correct" load...
  18. ukbridge

    Future of Connection Design

    Hopefully not! In my opinion its the launch of more comprehensive software - for example design of RHS/CHS joints to EN 1993-1-8. I think theres a lot of scope for a decent developer to come along, create a good application that quickly and efficiently enables designers to sign off connection...
  19. ukbridge

    Cantilever retaining wall design

    Couldnt agree anymore with Hotrod, oldestguy and Fatdad really. In my view designing for k0 earth pressures is a simple, conservative (but not unreasonably) so way of designing relatively stiff RC retaining walls e.g. bridge abutments (obviously more flexibile types are a completely different...
  20. ukbridge

    Shear in concrete T-sections

    Keep it simple and check it as a series of rectangular beams.

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