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