simdesign.rcmrf.bnsm.cp03

BNSM CP03 Library

This package provides an instantiable lumped-plasticity modelling strategy within the Building Nonlinear Structural Model (BNSM), suitable for performance-based seismic assessment of existing reinforced concrete (RC) moment-resisting frame buildings. It extends CP01 by explicitly introducing plastic hinges via zeroLength elements for beams and columns. Furthermore, rigid joint offsets are defined using rigid-like elements rather than geometric transformations.

The classes defined here inherit from the abstract modelling interfaces in bnsm.baselib and extend the CP01 implementations where required, providing instantiable component implementations.

Model Characteristics

  • Beam: Concentrated plasticity (CP) with explicit zeroLength end hinges placed in series with an elastic interior beam element. Hinge moment-rotation behaviour follows CP01, with elastic stiffness modification according to Ibarra & Krawinkler (2005).

  • Column: Concentrated plasticity with explicit zeroLengthSection end hinges and an elastic interior column element. Flexural hinge behaviour follows CP01, with elastic stiffness modification according to Ibarra & Krawinkler (2005) and optional degrading shear hinges supported through the inherited CP01 Column.

  • Joints: Rigid joint offsets are modelled explicitly using rigid-like elasticBeamColumn elements, rather than through geometric transformations applied to beam-column elements. Beam-column joint springs may be defined as rigid, elastic, or inelastic, consistent with CP01.

  • Infill: Equivalent diagonal strut macro-model for masonry infills (identical to CP01).

  • Floor Diaphragm: Rigid diaphragm modelling via retained node and multi-point constraints (identical to the base implementation).

  • Foundation: Lumped fixed support node (identical to the base implementation).

  • Building: Aggregator class assembling all nonlinear components into a unified OpenSees domain. Extends base implementation by introducing auxiliary plastic hinge nodes, rigid-like offset elements, and configurable series or parallel infill-column shear interaction.

References

Ibarra, L. F., & Krawinkler, H. (2005). Global collapse of frame structures under seismic excitations. Technical Report 152, Stanford University.