Thank you very much Mr. Nihesh
Response spectrum analysis gives absolute values of forces and moments. that is ok.
The BMD for response spectrum case does not change the sign at the
midspan of beam as all the values are positive. Thus, beam and column support moments
are obtained correctly by using + and - sign in load combinations but the values at
midspan of beams can not be directly used in design as it is also getting added and
subtracted. In reality, for lateral load case, the midspan moment in beams is nearly zero. How to take care of this during the combination of loads, to obtain actual span moments.
awaiting your reply
with warmest regards