How do I solve the BMD of a fixed beam with the load at midpoint?

 

How do I solve the BMD of a fixed beam with the load at midpoint?

BMD of a fixed beam

Read any book on indeterminate structures.

You must know

Fixity moment or fixed end moment when point load acts at midspan is=PL/8

Maximum bending moment due to point load on simply supported beam is at midspan and is equal to PL/4.

So draw BMD for fixed end moment as negative and for loading as positive.

You see the final BMD in third figure.

In softwares like Staad Pro you will see they have made different BMD, because these softwares always shows the net Bending moment in BMD. So they just cancel equal positive and negative area and hence they get BMD as follows