Learning Forum

[bidhek]

Actually, I am trying to learn time history analysis in Workbench for a nonlinear structure, while applying acceleration in full transient analysis for nonlinear analyses, I am not being able to set boundary conditions while selecting base excitation for application of acceleration time history. Can I get any suggestions or procedures for performing time history analysis for a nonlinear reinforced concrete structure?

[peteroznewman]

You have two choices.

1. Use Fixed Supports on the base and apply an Acceleration load. This will act on the mass of the structure.  All the displacements in the solution will be relative displacements to the base. This is your best choice.

2. Use matlab or other program to perform numerical integration on the acceleration-time history to compute the displacement-time history. Use that in a Displacement boundary condition.  All the displacements in the solution will be absolute.  In order to see the relative displacement of the tip of the model, you have to subtract off the base displacement. This is a pain. If you only care about stress or strain, then you get that without any extra effort.

[bidhek]

Thank you so much Mr.Peter. I will try your suggestions. I may need more suggestions further, so I will not close this discussion. 

thank you..

[bidhek]

respected Mr. Peter,

I have tried to do as you said but I am not being able to select the boundary conditions while I select the base excitation. I have attached the screenshot along with ANSYS workbench model file could you please help me figure it out.

[peteroznewman]

Set Base Acceleration to No to use the Acceleration load.

[bidhek]

actually, I need to apply the base acceleration for seismic analysis of the shear wall to check the time history at different location of the shear wall. Is there any  other way to apply base acceleration for full transient analysis for nonlinear time histories analysis in workbench without the linking transient with modal analysis?

[peteroznewman]

In a Transient Structural, with no Modal, you can apply Displacements to the base supports. 

Use matlab or other program to perform numerical integration on the acceleration-time history to compute the displacement-time history. Use that in a Displacement boundary condition.  All the displacements in the solution will be absolute. 

[bidhek]

thank you Mr peter,  I will try your suggestion.

[mustafas]

Hi Mr.Peter,

For Non-Linear Transient Analysis, if the base excitation is selected YES, boundary conditions can not be selected, a yellow highlight is present. If selected NO, then All Bodies is the only selection.

Hence I am kindly asking how to perform Non Linear Transient Analysis by applying acceleration to a boundary condition ?

Thanks,

[Randel Ilumin]

Hello. I would like to ask how about the weight or effect of gravity load? Is it right to add +9.81 to the vertical acceleration component?