Modelling Isolators on Lusas

[AdRo777]

Hi, I am a student tasked with an assignment on "the response analysis of base isolated bridges under seismic loads" and I am using LUSAS to carry out this task which I have some experience with. For it I have to model a bridge with and without isolation and apply seismic loading then compare the responses from each model. The bridge model does not particularly matter so long as it shows a different effect with and without the isolator so can be relatively simple. I have tried using the joint function with the lead rubber bearing option but cannot get my model working with it. Alternatively my lecturer has suggested modelling isolator properties on to a line element but i also cannot figure out how best to define isolator properties without using the bearing functions. Would anyone know what my best way to approach this would be? Any tips would be a great help.

 

[bkal]

I do not know much about Lusas, but generally you could model a bearing with three springs (one for each orthogonal translational direction). Hopefully, bearing manufacturer can provide their stiffness and damping properties. Unless they are large on plan, I would imagine that stiffness for rotation is important.