Seismosoft | Earthquake Engineering Solutions

How Can I apply load on the middle of the beam?

One way would be to subdivide the beam into an even number of elements. On the "Element Connectivity" tab, first select the element in question and then click on the "Subdivide" button, at which point you'll be asked into how many elements you wish to divide the beam. Select 2, 4, or 6. You will then have a node at the center of the beam to which you may apply loads.

Best of luck with your work.