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.