Computers and
Structures, Inc. (CSI), leader in software tools for structural and
earthquake engineering, has released 5.0.1 version of PERFORM-3D is a
structural-engineering software useful for the performance assessment of
structural systems.
Traditionally, earthquake-resistant design has been strength-based,
using linear elastic analysis. Since inelastic behavior is usually
allowed for strong earthquakes, this is not entirely rational.
Strength-based design considers inelastic behavior only implicitly.
Displacement-based (or deformation-based) design considers inelastic
behavior explicitly, using nonlinear inelastic analysis.
Displacement-based design recognizes that in a strong earthquake,
inelastic deformation (or ductility) can be more important than
strength. PERFORM-3D allows you to use displacement-based design.
Procedures for displacement-based design using inelastic analysis are
specified in ASCE 41, 鈥淪eismic Rehabilitation of Existing Buildings鈥.
ASCE 41 applies to the retrofit of existing buildings, but the
procedures can be applied to the design of new buildings. PERFORM-3D
implements the procedures in ASCE 41. However, PERFORM-3D is a general
tool for implementing displacement-based design. It is not limited to
ASCE 41.
The response of a structure to earthquake ground motion, whether
elastic or inelastic, is highly uncertain. Capacity design is a rational
way to improve the response of a structure in a strong earthquake, by
deliberately controlling its behavior. Capacity design controls the
inelastic behavior of a structure, by allowing inelastic behavior only
in locations chosen by the designer. In these locations the structural
components are designed to be ductile. The rest of the structure remains
essentially elastic, and can be less ductile. Controlling the behavior
in this way improves reliability, reduces the amount of damage, and can
reduce construction costs. PERFORM-3D allows you to apply capacity
design principles.
PERFORM-3D has powerful capabilities for inelastic analysis, but it
is not intended for general purpose nonlinear analysis. If you have no
idea how your structure will behave when it becomes inelastic in a
strong earthquake, PERFORM-3D can probably help you to identify the weak
points, and hence can guide you in improving the design. However,
PERFORM-3D is not intended for 鈥渄esign by analysis鈥, where the engineer
expects the analysis to determine exactly how a structure will behave.
PERFORM-3D is a powerful tool for implementing displacement-based design
and capacity design. It will help you to produce better designs, but it
will not do the engineering for you. |