section recorder

[benliangxiao]

Hi,

I'm running a 3D model and using the following commands to record the responses for a bridge column

recorder Element -file def.txt -time -ele 100 section 10 deformation;
recorder Element -file force.txt -time -ele 100 section 10 force;

The results have 7 columns with the first one as the time. I was wondering what the other six columns are.

Thanks,
Xiao

[benliangxiao]

By the way, it's a circular column.

Thanks,
Xiao

[selimgunay]

They are the six internal forces (2 moments, 2 shears, axial force and torque) and the corresponding sectional deformations. To figure out which column is which force or def, you can run a quick analysis with a low level ground motion that would lead to elastic response and divide the resulting forces by the displacements. For example, M/curvature should be close to EI and axial force/strain should be EA.