rossparkeruk
Civil/Environmental
- Sep 7, 2011
- 1
Hi,
I am currently modelling a reinforced concrete column in ANSYS, and I am getting some strange results.
I am trying to see the effect of adding more steel links at the bottom of concrete columns, and finding the ultimate load of these columns. To do this I have created several models varying the spacing of the steel links at the bottom of the column.
I was expecting that the more steel I added to the column, the greater the ultimate load. However, I have been finding that the more steel that I add, the earlier the column fails. They tend to fail due to the solution not converging, not due to a large displacement for a small load, which leads me to believe that there is a convergence problem with the model, stopping the solution from progressing before the column reaches its ultimate load.
I am a relatively new ANSYS user, and so I am wondering whether I have missed some key information out of the model. After many internet searches I have tried various things such as increasing/reducing the convergence criteria (reducing to 0.05% of the force and 0.5% of the displacement, and increasing to 0.5% of the force and 5% of the displacement) and increasing the equilibrium iterations (to 50) but to no avail - the solution still has trouble converging. I have also tried playing around with the shear transfer coefficients of the concrete but again this hasn't helped.
I am modelling the concrete as SOLID65 elements and the reinforcement as LINK8 elements. The nodes are shared so there is a perfect bond between the concrete and steel. The base of the column is modelled as an elastic foundation of depth 1m (modelled using springs with stiffness EA/l), and the top of the column has been restrained in the horizontal plane, allowing displacement in the vertical direction only. The column has been loaded with a pure axial load, applied as a surface pressure.
If anyone has any ideas as to what might be going on, I'd really appreciate some help!
Thanks,
Ross
I am currently modelling a reinforced concrete column in ANSYS, and I am getting some strange results.
I am trying to see the effect of adding more steel links at the bottom of concrete columns, and finding the ultimate load of these columns. To do this I have created several models varying the spacing of the steel links at the bottom of the column.
I was expecting that the more steel I added to the column, the greater the ultimate load. However, I have been finding that the more steel that I add, the earlier the column fails. They tend to fail due to the solution not converging, not due to a large displacement for a small load, which leads me to believe that there is a convergence problem with the model, stopping the solution from progressing before the column reaches its ultimate load.
I am a relatively new ANSYS user, and so I am wondering whether I have missed some key information out of the model. After many internet searches I have tried various things such as increasing/reducing the convergence criteria (reducing to 0.05% of the force and 0.5% of the displacement, and increasing to 0.5% of the force and 5% of the displacement) and increasing the equilibrium iterations (to 50) but to no avail - the solution still has trouble converging. I have also tried playing around with the shear transfer coefficients of the concrete but again this hasn't helped.
I am modelling the concrete as SOLID65 elements and the reinforcement as LINK8 elements. The nodes are shared so there is a perfect bond between the concrete and steel. The base of the column is modelled as an elastic foundation of depth 1m (modelled using springs with stiffness EA/l), and the top of the column has been restrained in the horizontal plane, allowing displacement in the vertical direction only. The column has been loaded with a pure axial load, applied as a surface pressure.
If anyone has any ideas as to what might be going on, I'd really appreciate some help!
Thanks,
Ross