06-09-2010, 01:18 PM
For Capacity Design (weak beam strong column), in design you can take beam stiffness 50% of its full stiffness while still maintaining column stiffness to 100% of its full stiffness or :
Beam, I design = 50% I gross beam
Column, I design = 100% I gross beam
ACI uses :
Beam, I design = 35% I gross beam
Column, I design = 70% I gross column
or in general, I beam reduction factor is half of that I column reduction factor.
These apply to Ix, Iy & J (Torsional constant; - not polar moment of inertia).
Reinforcement detailing is also important provide this mechanism.
Beam, I design = 50% I gross beam
Column, I design = 100% I gross beam
ACI uses :
Beam, I design = 35% I gross beam
Column, I design = 70% I gross column
or in general, I beam reduction factor is half of that I column reduction factor.
These apply to Ix, Iy & J (Torsional constant; - not polar moment of inertia).
Reinforcement detailing is also important provide this mechanism.