Last Updated August 17, 2017
In PERFORM-3D, most elements are made up of a number of components. For example, a beam element might consist of several components.
All inelastic components have essentially the same force-deformation relationship. This is a basic tri-linear relationship, with optional strength loss that can be captured in PERFORM-3D.
The hysteresis loop for an inelastic component can be varied to account for stiffness degradation. The loop can be plotted to check that it has the expected shape.
PERFORM-3D includes a large number of components, both inelastic and elastic. During an analysis, D/C ratios are calculated as follows:
Deformation capacities can be specified for inelastic components, for calculating deformation demand/capacity ratios. Deformation capacities can be specified for up to 5 performance levels.
The number of components with D/C ratios can be very large. To simplify decision making, components that have similar D/C measures can be grouped into Limit States. An example D/C measure is the concrete tension strain in a shear wall. Each limit state has a “usage ratio”, which is the maximum D/C ratio for any component in the limit state. For a structure to satisfy the performance requirements, the usage ratios for all limit states should not exceed 1.0.
Simple frame structures consist of beam and column elements. Beam and column elements can be made up of a variety of components, and may be elastic or inelastic. P-delta effects can be considered or ignored.
Shear walls are modeled using plane wall elements. Complex shear cores are made up of plane elements. Wall elements can have inelastic behavior in bending and shear. Coupling beams are usually modeled using beam elements, with inelastic behavior in either bending or shear.