The OpenSees Community

Hi Vesna, Thanks for notifying me this. Is it because the zerolengthsection element doesn't output disp but curvature instead? I tried zerolengthsection since some of the researchers used zerolengthsection element to model Strain penetration effect. It actually makes sense that the a "section" can o...

Hi Vesna, I observed an interesting result when recording global and local forces. In a 2D cantilever model, I used one beam column element. Global force and local force are the same since I applied the default orientation of the section that local coordinate coincide with global coordinate. When I ...

Hi Hidemasa, I am working on rotational spring, too. The element I used is zerolength element. Are you using this element also? Thanks. Yuhao Hidemasa KAIHARA wrote: > Hi, > > I have a question. > Generally, the performance of rotational spring gives Moment-angle > relation. > According to the Comma...

Hi Vesna, I wrote a static analysis script for rotational spring. Though I specified integrator to be displacement control, OpenSees kept showing me warning " no Integrator specified". I checked a lot of times and failed to find the problem. Can you take a look at it? Thanks # unit is in ksi kips # ...

Vesna,
The way to assign moment-rotation ralation is to play with the material in the element, right?
Thank you.

Yuhao

vesna wrote:
> You can use zeroLength element and assign moment-rotation relation in direction 6.
> Do not forget to equlDOF all other dofs.

Hi all,
What is the best way to model a nonlinear rotational spring? The spring should have a flexible force displacement response (moment_rotation) that can be specified.
Does anyone have some experience on that?
Thank you.

Yuhao

Nice. Let me try your method and see what I get. Thank you. Yuhao vesna wrote: > What I do is the following: > since I know position of the last two integration points (e.g., if #IP=5, > one point is going to be at location 0, and another point is going to be at > 0.173L, where L is the length of th...

Vesna, With one beam with hinge element, I imposed the calculated plastic hinge length to the weight of the base integration point which is at the fix end. I also tried one nonlinear beam column element to mode the column. For this case, I used 5 integration points along the element that the weight ...

Hi Vesna, Yes, I recorded the strain at plastic hinge region. In the experiment, cracks were all over the length of the whole column and concentrates in plastic hinge region. We block out the cover concrete of our column and put a series of LED sensors along the bar to cover the whole plastic hinge ...

Hi Vesna, I am using a beamcolumn element to model a RC cantilever. I tried beam with hinge element, nonlinear beam column element and displacement based element. The material constitutive model is calibrated also based on material test result. Meanwhile, we are doing some experimental tests in the ...

Frank, Yes. I am using force based Beam with hinge element. But acturally, I am reducing the time step and the result varies. Do you have any suggestion on selecting the time step? Yuhao [quote="fmk"]a problem with increasing time step is that the changes in the response get larger at each step (dU)...

Vesna,
Yes, my tolerance is 10^-8.

Yuhao

[quote="vesna"]Yuhao,
What is the tolerance for the test? For EnergyIncr convergence test (residual force)*(incr disp)<tol. This would mean that your tolerance is on the order of 10^4. Please check on this one.[/quote]

Vesna, I have significant deviations. I reduced the time step because model cant converge at a specific time during dynamic analysis. I also checked the norm unbalance force and incremental displacement at the point which fail to converge(i am using EnergyIncr convergence test). Interestingly, resid...

Hi Vesna, We said analytical time step is ok as long as it is less than 1/10-1/20 of natural period. Most of the examples in OpenSee example manual is making DtAnalysis equate to ground motion time step. And myself used the time step of ground motion as the analytical time step also. It works pretty...

Hi all,
Can the velocity time history be the input ground motion for dynamic analysis? Or can we use UniformExcitation Pattern with velocity or displacement?


Thank you.

Yuhao