Pushover direction

[simonkey]

If I enter values for both the x(dof 1) and y(dof 2) directions of the load command when defining the lateral pattern for pushover analysis on a 3d model, what exactly happens in opensees?

ie if I put x(dof1) direction in the integrator command after defining the lateral pattern, do the y values in the pattern get factored?

is there a way to put dofs 1 and 2 in integrator command?

[hugo_esquivel]

I think you cannot at this moment... However a solution to this is to try to rotate the model... Hint: define the nodes as function of the angle of rotation so you can applied the load pattern in one of the global axes.

Hope it helps.

PS: According to your post, I presume you are using loadcontrol as the integrator to perform the pushover... to go further in the analysis is recommended to use displacementcontrol instead.

[simonkey]

Thanks Hugo,

I agree with your idea of rotating the coordinate system for the model.

To clarify my earlier post, I was referring to the displacement control integrator.

I believe that, for this integrator, one must first define a lateral load pattern using the pattern and load commands. At this stage, my question was regarding the difference between "load nodetag Hx Hy 0 0 0 0" vs "load nodetag Hx 0 0 0 0 0".

For the latter case, if I analyze with x-dof in integrator command, I understand that the Hx pattern is factored until the desired max displacement is reached - but for the former load command, do "Hy" values also get factored?

The second issue I wanted to see if anyone can help me clarify is that, after performing a pushover with, say, lateral load pattern defined in both directions and x-dof in integrator command, I obtain displacement values in both x and y directions for the master node because it is a 3d model. In this situation, do you think it's a good idea or not to plot the pushover curve by using SRSS of x and y comp of disp and total reactions considering the fact that I used x-dof in the integrator command?

[hugo_esquivel]

[quote="simonkey"] For the latter case, if I analyze with x-dof in integrator command, I understand that the Hx pattern is factored until the desired max displacement is reached - but for the former load command, do "Hy" values also get factored?[/quote]

It depends on your model... the load patterns are only factored if they are required to maintain the displacement increment at that value specified by the integrator.

[quote="simonkey"] The second issue I wanted to see if anyone can help me clarify is that, after performing a pushover with, say, lateral load pattern defined in both directions and x-dof in integrator command, I obtain displacement values in both x and y directions for the master node because it is a 3d model. In this situation, do you think it's a good idea or not to plot the pushover curve by using SRSS of x and y comp of disp and total reactions considering the fact that I used x-dof in the integrator command? [/quote]

It depends on what you really want to do with the info... I think it will be ok.

[simonkey]

Do you know how to keep track/record the load factors that are applied to the load pattern when using the displacement control integrator?

[hugo_esquivel]

All load patterns are factored with the same value... so use the base shear as a reference.

[simonkey]

Thanks for your help