Why bent up bars are provide in beams?

Answer 1

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!