Forum for OpenSees users to post questions, comments, etc. on the use of the OpenSees interpreter, OpenSees.exe
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- Posts: 43
- Joined: Fri Jan 29, 2016 10:20 pm
Dear Community Members
Could anybody please give me an example to analyze a RC cantilever subjected to reversed cyclic displacement loading, using arc length integrator.
I know this problem is easily solvable using displacement control integrator, I just want to know. How can we solve this problem using Arc Length integrator.
Unlike displacement control integrator (integrator DisplacementControl $node $dof $incr), arclength integrator (integrator ArcLength $s $alpha) does not have any option to specify node and corresponding DOF at which the displacement is applied. Then how can we specify the node and corresponding dof at which the displacement is applied?.
Thanks and regards
- Posts: 3
- Joined: Fri Aug 17, 2018 12:32 am
You don't specify node in arc-length method because at each increment the controlling parameter that is being incremented is <s> (the arc-length) and this parameter is derived by taking into account all displacements at dofs (plus the load parameter in case of spherical arc-length). Instead, you specify the parameter <s> and at each increment an additional constraint has to be satisfied which, when converged, forced the next solution point to a)lie on the equilibrium path and b) satisfy dot(Du,Du) + alpha*lambda^2*dot(Fb,Fb) = s^2. Alpha is the second input for the arc-length. Set it to zero if you don't want to think much about it. This yields the so-called Cylindrical Arc-Length.