I am attempting to study the effect of pier settlement of unreinforced masonry arch bridges on the structural health of the bridges. I am using a macro-modelling approach as I am not interested in collapse mechanisms but rather early stages of structural deterioration.
I have modeled a bridge using different bodies with bonded contacts between the structural parts of the bridge (spandrels, arch barrels, foundations, abutments, backwalls and pier), and frictional contact between the fill and the surrounding parts.
I am aiming to get crack plots and so have used APDL commands to make use of Solid65 elements in all of the structural bits (with material properties adjusted accordingly).
I have constrained the model using fixed supports under the foundations and modeled settlement of the pier by defining a transnational and rotational displacement applied to the pier in the middle.
The problem I am facing is the model doesn't converge due to errors in element formulation; I have tried adjusting contact stiffness of contacts I identified using NR Residuals, refining the mesh, increasing steps and substeps to gradually apply the displacement and everything I could find which may help but the model doesn't converge unless I suppress the fill.
The fill is a mohr-coloumb material I defined and I suspect is the issue behind the convergence dilemma.
Any help or insight would be greatly appreciated.