The Mesh Merge has stitched all the meshes together. You can see this using Edge Coloring and set it to By Connection.
I added Remote Displacements to the end of each arm and moved them down 100 mm.
Since you have Plasticity in your model, you must make some adjustments to the Analysis Settings.
I broke the analysis into 2 steps so that few substeps could be made in the first step and more substeps could be taken in the second step.
Below is the Reaction Force vs Displacement of the end of the arm.