Help Pretensioning of bolt

Dear All,

I have a 2d axisymmetry model of a steel rod embedded in concrete. A 
nut and bearing plate is used to pretension the steel rod. How can i 
best model this. 

At the moment i am using connector elements to connect the nut and 
steel rod. I have specified the connector behaviour based on the 
nonlinear load-displacement characteristics obtained in experiments. 
I have specified the elastic behaviour of the connectors (F1-U1). 
But when i modified the values it has absolutely no effect on the 
model, infact i had to apply 6 connector elements at every node 
along the steel rod/nut interface. I don't think this is the right 
way to model this. Can anyone please help me?

If you need to visualize it kindly go to 
www.geocities.com/ravindran_manoharan/anchor.html 

i hope someone could shed some light on this.

With best regards,
Ravi








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