Picture shows a prefabricated concrete staircase landing supported on a steel angle.  The concrete is vulnerable to stretching stresses.  In this case they were concentrated in a small area.  This kind of fracture may lead to the corrosion of reinforcement inside concrete. The supportive shelf shall be covered with a pad distributing stress uniformly to prevent stress concentration. The thick steel angle has been welded to a surprisingly lightgage sheet metal wall frame which does not look reliably enough.