Moving load analysis in Abaqus

[Error.n.n]

hello everyone,

I am new to abaqus and from most of the tutorials I have seen, Abaqus is mostly used for modelling sections of elements, like one beam. I would like to model a full bridge in Abaqus and apply a set of moving loads obtained from real traffic data. is that possible or should I consider using another software. I chose abaqus because it has the capability of using python scipts and my assumption was I could define the traffic in python and apply it the bridge model in Abaqus. Please let me know if there is another way too.

 

[FEA way]

Well, Abaqus can analyze much more than one beam ;-)

You could try modeling a bridge (with some simplifications) but moving loads will be problematic since Abaqus doesn’t have a dedicated feature for them. You would have to use a subroutine, scripting or some workarounds but it won’t be easy go apply a moving load from traffic data.

However, there’s a separate software named BRIGADE. It’s based on Abaqus and meant specifically for bridge analyses. Of course it features easy definitions of moving loads. Check it out if it seems to be helpful for you. Unfortunately, you would need a separate license for this software.

 

[Error.n.n]

Thank you for your quick response @FEA way. So the aim of my model is pretty simple and not what is commonly used for Abaqus software. Unfortunately, the school software only has a paid subscription for Abaqus. I guess I will have to learn how to use the d-load subroutine and Python scripting. I will ask for a free trial of the recommended software, Brigade, but I don't know how long they provide it for.

I am remodelling a constructed steel-composite girder bridge, and I would like to check if there is any yielding occurring in the critical components of the bridge known to be prone to fatigue damage when i apply the traffic data set that i have.

In the meantime, where can I find reasonable tutorials on modelling steel and composite bridges in Abaqus?

Or better yet, can you assist me in solving a number of errors I am getting in the model that I have setup? I have used shell elements to model the deck and main girder with stiffeners, and beam elements for the secondary bracing. I used tie constraints to model the interaction between the girder top surface and composite bridge top surface and tie constraints for the connection between the beam node and the stiffener shell. The analysis keeps aborting after many unsuccessful attempts, despite trying all the fixes on the internet for the following errors.

Error #1: Secondary surface assembly__pickedset420_cns_ is a node-based surface used with a surface-to-surface approach. In order to obtain improved stress accuracy with this approach, an element-based surface should be used instead.

Comment: I believe this error is related to the tie constraint i used for the connection i used for the secondary beam nodes to the stiffener shell. I tried to remove the constraints and merge the nodes but now I have an error about unconnected regions. How can i fix it?

Error#2-6:
The system matrix has 3 negative eigenvalues.
The strain increment has exceeded fifty times the strain to cause first yield at 349533 points
The strain increment is so large that the programme will not attempt the plasticity calculation at 459783 points
The plasticity/creep/connector friction algorithm did not converge at 2234 points
Excessive distortion or excessive rotation of the normal in 3 shell elements

Comment: The negative eigenvalues may have been caused by the rotation of the shell elements, which are the stiffeners. If i can solve the connection between those two, i think it will go away.
However, the error for strain increment remains the same at the same exact points even when I change the materials from plastic to elastic. I have only applied gravity loads for this step.