Dear paladin,
First things first. If your structure is old, therefore analyzed using old design codes, then there are more variables to consider on the form and properties of the hinge type you will use. If the structure is studied using relatively new codes, then the hinge will probably have ductile properties (bending failure at beam end) instead of shear resistance incapacity (brittle failure). Then you use M type hinge.
Answering your question, you need to estimate how much more reinforcement (shear and bending) was used by the first engineer than necessary. If they are close in percentage, see if there are solutions to prevent shear failure at the end of your beams, such as shorter distance between shear reinforcement compared to the mid-span of the beam. If this is the case, then I would use M type plastic hinge. Besides, in FEMA356 (Prestandard and commentary for the seismic rehabilitation of buildings), which I recommended earlier, you do take into consideration the shear reinforcement in an M type hinge. Pushover is relatively new, so what you do is an evaluation of the method itself.
FEMA 356 (2000)
First things first. If your structure is old, therefore analyzed using old design codes, then there are more variables to consider on the form and properties of the hinge type you will use. If the structure is studied using relatively new codes, then the hinge will probably have ductile properties (bending failure at beam end) instead of shear resistance incapacity (brittle failure). Then you use M type hinge.
Answering your question, you need to estimate how much more reinforcement (shear and bending) was used by the first engineer than necessary. If they are close in percentage, see if there are solutions to prevent shear failure at the end of your beams, such as shorter distance between shear reinforcement compared to the mid-span of the beam. If this is the case, then I would use M type plastic hinge. Besides, in FEMA356 (Prestandard and commentary for the seismic rehabilitation of buildings), which I recommended earlier, you do take into consideration the shear reinforcement in an M type hinge. Pushover is relatively new, so what you do is an evaluation of the method itself.
Code:
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Sometimes, less is more