Hi All,

I am currently modelling a Steel Plated Concrete (infill) Composite Wall under Earthquake loading (Ground motion data) using ABAQUS at the moment. I have got a natural period of my structure is 0.009 seconds as it is just a 1.2m x 1.2m wall with 0.2m thickness(190mm concrete and two 5mm steel plates). 

I have been advised to model the wall as a part of a low rise structure without physically modelling the complete structure and the way to do this I have been advised is to increase the period of the structure to match that of a low rise structure which is around 0.3seconds. 

As the natural period of the structure is:

T = 2Pi/w

as w = (k/m)0.5

I had tried to increasing the density of the materials to get the natural period of the structure to increase. This actually works and the job runs, but my supervisor had advised that this is not a good way to simulate these conditions. 

I have been advised that most FEM programs have an option to add masses to the nodes. Does Abaqus have a similar option?As I have not been able to find such an option thus far.