Civil Engineering Reference
In-Depth Information
Figure 9.13
Implementation of PCPlaneStress module into OpenSees
uniaxial steel and tendon objects, respectively, and receive the tangent stiffness and stress from
the related uniaxial steel and tendon objects. After receiving the uniaxial stiffness and stress
of each of concrete, tendon and steel, the tangent stiffness matrix can be evaluated and the
stress vector calculated.
Meanwhile, the displacement control scheme in the OpenSees was modified for an arbitrary
displacement path. The user can define the displacement paths of the degree-of-freedom of
the node whose response controls the solution. Or, the displacement increment for each path
of the displacement scheme may be varied. Changes in the size of the displacement increment
make it possible to overcome some numerical problems in the nonlinear analysis.
In addition, some classes are modified to overcome or bypass the numerical problems
occurring in the analysis of nonlinear problems. For example, the analytical models about
the convergence check are modified. Instead of giving one maximum iterative number for
all increments, the user can decide different maximum iterative numbers for different paths
in the displacement control history. Users can increase the maximum iterative number in the
specified path that may have numerical problems. Lower iterative numbers in the rest of the
displacement paths are defined to save computing time.
After implementing the new material models and modifying relevant existing classes in
OpenSees, a finite element program named SCS (Simulation of Concrete Structures) was
developed by adopting the OpenSees as the finite element framework. This program is able to
perform nonlinear finite element analysis of concrete structures under static, reversed cyclic,
or dynamic loading. Chapter 10 supports the application of SCS to reinforced/prestressed
