it is actually economization of material. normally, for
fixed ended beams positive (sagging) moments are present at
the mid span and negative (hogging) moments at the supports.
so bottom steel is required at the mid span and top steel
resists negative moments at the supports. a bent-up is
provided to take the steel on the top at supports as bottom
steel is not normally required at at the supports (only
nominal steel is sufficient). hope it'd help!

the bars are needed to avoide the bending moment,so the
cover provided is very large in some spans,the shears
double its speed as its age carries beyound 28 days causing
cracks in many beams, columns, so on, it is purely needed
for the negative + moment on the ends to crack it like a
crack jack biscuit, you have a jig and puzz to solve the
pozzle, the 40mm and 90mm low waist jeans type hanging is
what required for the howay beam when Formula of

Beam depth = 30mm* (F*ck + root of 149 carrot inside the
asshole is emerging ,that moment the carrot rises to 90
degree shot with a temperature of 70 degrees celcius ),the
bending moment sags as soon as the juice is over...
negative bending moment happens.

Now, yield strength of steel rod... when its hot then it is
highly hot ..strength reches beyond
aaaaaaaaaaaahhhhhhhhh uuuuuuuuuuumuuuuuuuuuuuhaaaaaaaaa

so team members avoid learning frm net use your own brains
n live happily...