We would like to ask a PMM non-linear spring for modeling Plastic Hinges for reinforced-concrete Columns. This PMM springs are used for modeling the Moment-Rotation (M-R) behavior for different axial loads (P). The PMM spring should be able to capture the M-R curve for each (considered) axial load (in compression and tension). Like in any reinforced-concrete column interaction diagram, an elastic-perfectly-plastic moment-rotation behavior will create a "yield" surface describing the all possible combinations of axial and moment along each principal axis. This PMM Hinge should also be capable of using the TAKEDA hysteresis rules for reinforced concrete in a NLTHA.

In a pushover analysis, as well as in a NLTH analysis, when we have the plastic hinge located in a multi-column bent, the level of axial load varies (due to the frame action for transverse demands). In consequence, the PPM shall recognize these axial load variations, and adjust the Moment-Rotation to be used in the analysis. In general, a column with high axial load has higher moment capacity, but less rotational capacity, than a column of lower axial load. This structural behavior is key in seismic design.