Slip or permanent displacement during Earthquake Excitation
Slip or permanent displacement during Earthquake Excitation
(OP)
Hello everybody
I am doing dynamic analysis of a rocking wall. In the first step i applied the self weight and post-tensioning and base of the foundation was fixed in all DOF. In the 2nd step i have to apply dynamic loading. So i free the horizontal DOF of foundation base (EQ will be applied in Horizontal DOF) and then acceleration is applied at the wall base in horizontal direction. After running analysis when i check the Horizontal displacement of foundation it shows that there is some slip occured during the dynamic loading. Actually this displacement should be like a sine wave along the zero displacement line but it shows permanent displacement of whole structure (Like slip). At the end of the analysis structure has 250mm of permanent lateral displacement in the lateral direction. You guys have any idea abt this problem? am i applying EQ in the right way?
Regards
Irshad
I am doing dynamic analysis of a rocking wall. In the first step i applied the self weight and post-tensioning and base of the foundation was fixed in all DOF. In the 2nd step i have to apply dynamic loading. So i free the horizontal DOF of foundation base (EQ will be applied in Horizontal DOF) and then acceleration is applied at the wall base in horizontal direction. After running analysis when i check the Horizontal displacement of foundation it shows that there is some slip occured during the dynamic loading. Actually this displacement should be like a sine wave along the zero displacement line but it shows permanent displacement of whole structure (Like slip). At the end of the analysis structure has 250mm of permanent lateral displacement in the lateral direction. You guys have any idea abt this problem? am i applying EQ in the right way?
Regards
Irshad





RE: Slip or permanent displacement during Earthquake Excitation
RE: Slip or permanent displacement during Earthquake Excitation
Contact is established between the wall and the foundation with both normal and tangential behavior. Behavior of the structure is non-linear. There is a chance of slip movement between wall and foundation but it was observed to be zero rather foundation was slipping. For more information kindly take a look at this video.
http://www.youtube.com/watch?v=Xc0zeI2Qtio&fea...
Thx for ur reply
Regards
Irshad
RE: Slip or permanent displacement during Earthquake Excitation
I think that what you want to do is as follows:
- have a proper contact model between the base of the wall and the foundation, including friction.
- apply input motion to the foundation, not the wall.
RE: Slip or permanent displacement during Earthquake Excitation
RE: Slip or permanent displacement during Earthquake Excitation
RE: Slip or permanent displacement during Earthquake Excitation
Thx alot :)
RE: Slip or permanent displacement during Earthquake Excitation
RE: Slip or permanent displacement during Earthquake Excitation
http://www.flickr.com/photos/93814781@N03/87193161...
http://www.flickr.com/photos/93814781@N03/87204391...
First one is the acc, velocity and displacement history of excitation.
Second one is the top displacement history of rocking wall.
RE: Slip or permanent displacement during Earthquake Excitation
RE: Slip or permanent displacement during Earthquake Excitation
This result is for a node at the top of the wall.
Actually i got this time history from the results of acceleromete in the shake table test of this wall. May be i need to do some kind of base correction for my excitation. Because this one is just raw result from accelerometer. What do u suggest?