8. P-D
effects may be more important than you think.
•The P-D effects become increasingly significant with larger lateral displacements and larger axial column forces.
•Strong column - weak girder design strategy commonly deals with the moment capacity of columns in the undeformed state.
•In a substantially deformed state, the moment capacity of columns may be sufficiently reduced to counteract the strong column - weak girder behavior envisioned by the design.
•Cases of plastic hinge formations during a push-over analysis in columns "designed" to be stronger
than the girders are not rare.
