I am trying to define hinge properties for steel columns according to FEMA 273 Table 5-6 in SAP2000. Calculating yield moment, yield rotation and other needed paremeters under changing axial load levels are understandable. But when it comes to defining moment-rotation relationship (considering different angles) i have some questions.
In FEMA it is explanied how to caluculate a,b and c points of backbone for principal axis. But when we consider biaxial bending it seems SAP uses a different approach. For example if we consider a column with point "a" of backbone curve for major axis (rmajor) is 9xyield rotation and 6xyield rotation for minor axis (rminor). If we want to determine the same value of the curve rotated 30 degrees, should we be doing r = rmajor x sin30 + rminor x cos30 (neglecting effects of lateral torsional buckling, local flange buckling etc.)? When i compare the values obtained by using the abovementioned formulation it does not match with SAP auto-hinge values.
Any help regarding to this question will me much appreciated.
In FEMA it is explanied how to caluculate a,b and c points of backbone for principal axis. But when we consider biaxial bending it seems SAP uses a different approach. For example if we consider a column with point "a" of backbone curve for major axis (rmajor) is 9xyield rotation and 6xyield rotation for minor axis (rminor). If we want to determine the same value of the curve rotated 30 degrees, should we be doing r = rmajor x sin30 + rminor x cos30 (neglecting effects of lateral torsional buckling, local flange buckling etc.)? When i compare the values obtained by using the abovementioned formulation it does not match with SAP auto-hinge values.
Any help regarding to this question will me much appreciated.
