• Registered: 2015-05-19
  • Posts: 15

Topic: Bearing plate material properties

Dear sir,

I am trying to model a prestressed girder at the stage of release. The girder is resting on two base plates that are each restrained along a line on their bottom surfaces. One bearing plate is restrained in all three directions; the other is restrained in all directions except for the direction parallel to the length of the girder (Y). The full length, but only half of the cross-section, of the girder is modeled. Therefore, the plane of symmetry is fully restrained in the X direction.

[X is along the width of the girder, Z is along the height of the girder and Y is along the length of the girder].

The contact surface between the girder and the base plate was automatically defined as "partial." I am having convergence issues that I think may relate to restraint-induced excessive cracking at the base of the girder at the time of release. I was wondering if there is a way to specify a material for the base plate that would only transfer normal stresses and not transverse stresses and would allow the girder to camber up?

In addition, I tried to changed the contact surface properties to "no-contact" assuming that it would then behave as a compression-only support. I got convergence errors at the very first step relating to "slips" in segment 1 of about 25 of the bars. The bar IDs mentioned in the error do not match the bar ID that I have specified for any of my reinforcement, so I could not identify which bars were causing an issue.

[I am using a CEB FIB bond model for the prestressed strands that are located at the top and bottom flanges of the girder. Other shear reinforcement are assumed to have perfect bond].

I would appreciate your input. Many thanks.

Quote Post 1

  • dpryl
  • CC software developer
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  • Registered: 2007-07-13
  • Posts: 1,107

Re: Bearing plate material properties

Dear rabyaneh,
I assume you work with ATENA Engineering 3D.

For general recommendations related to convergence issues, please see ATENA Troubleshooting, 2.1.19 Problems reaching convergence and understanding ATENA convergence parameters, 2.4.2 I get the message "The execution is killed due to violation of stop iteration criteria", what does it mean?, and 2.4.6 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, Warning: Sign of diagonal changed when reducing equation, Floating point exception: Multiple floating points traps, Zero or negative jacobian,  InvertA: zero determinant, CCMaterials Extended AExc: CC5ParamYield F: project_stress_on_f_division by zero, and similar. The current version of the document is available from our web (Products - ATENA - Documentation).

"No connection" means the 2 neighbouring Macroelements are completely separate - not connected at all through the automatically created contact (in other words, the displacements on the 2 surfaces are completely independent from each other).

If you wish to use an Interface Material, please first see Troubleshooting, 2.2.14 I have problems when using the Interface (GAP) material on contacts.

However, I would recommend to follow Troubleshooting, 2.1.11 Unrealistic damage near loading/support plates during shrinkage or pre- or post-tensioning.

With respect to the strands, you may also like to read Troubleshooting, 2.2.5 How to model bonded post-tensioning cables in ATENA?

If you can not solve the problems, you can send us your model (see Troubleshooting, 2.1.1).

dpryl's Website

Quote Post 2