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Elements
- PERFORM-3D includes the following element types:
- Frame element for beams, columns and braces.
- Wall element for shear walls.
- Slab element for floors.
- Bar elements (with only axial stiffness) of various types.
- Buckling restrained brace.
- Gap elements.
- Seismic isolators of rubber and friction pendulum type.
- Fluid damper, with nonlinear relationship between force and deformation rate.
- Connection panel zone, to model shear deformation in beam-to-column connections.
- Infill panel, with only shear strength and stiffness.
- Deformation “gages” of various types. These elements have no stiffness . They are used for calculating deformations, and hence deformation demand/capacity ratios.
Components
- In PERFORM-3D, most elements are made up of a number of components. For example, a beam element might consist of several components.
Component Properties
- All inelastic components have essentially the same force-deformation relationship.
- This is a basic tri-linear relationship, with optional strength loss.
Hysteresis Loops
- 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.
Deformation Capacities
- 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.
Demand/Capacity Ratios
- PERFORM-3D includes a large number of components, both inelastic and elastic. During an analysis, D/C ratios are calculated as follows:
- Deformation D/C ratios are calculated for inelastic components.
- Hence, components that are allowed to become inelastic can be checked to make sure they have sufficient ductility.
- Strength D/C ratios are calculated for elastic components.
- Hence, components that are required to remain essentially elastic can be checked to make sure they have sufficient strength.
Limit States
- 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.
Frame Structures
- 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 Wall Structures
- 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/or shear.
- Coupling beams are usually modeled using beam elements, with inelastic behavior in either bending or shear.
Complex Structures
- Large and complex structures can be analyzed.
Import from SAP2000 and ETABS
- Models can be imported to PERFORM-3D from SAP2000 or ETABS.
- These are partial models, consisting mainly of nodes, elements and loads.
- Component properties are not included, because these properties are different in PERFORM-3D than in SAP2000 and ETABS.
