BARSLIP Material

[aldoshoalv]

Hi everybody!

I am trying to simulate the behaviour of a beam column joint between precast concrete elements for my master thesis. In the OpenSees wiki states that one can specify the units of the material; about this, if I am using MPa, should I use meters for the lengths? Or shall I consider MPa as N/mm2?.

In a first approach, I was working my model with MN and meters, but then, I started to hesitate about the correct units for the BARSLIP. I changed my whole model to N and milimeters and that's when the analysis stopped to converge. I suspect that this could be because the values for the forces and the stiffness are too high in this units (N-mm).

I hope that I made myself understand. Thank you in advance,

Aldo Alonso Lugo Valadez
Structural Engineering Masters Program
Universidad Autónoma Metropolitana
Mexico City

[EricsonEncinaZ]

In OpenSees you have to be consistent with the basic units you are working on. If your basic units are: force in N, length in m and time in seconds, for example, then all the stresses should be given in N/m² = Pa, moments in N·m, kg in N·s²/m, ... etc.

It is important to note that some materials are unit-dependent and therefore they need the whole model to be defined in a specific set of units. As an example Bond_SP01 material require the use of kips and in as the units for forces and lengths, which means that if you use this material your whole model should be defined in those units.

So just be consistent with the set of units you selected, unless something in the model asks you to use a specific set of units.