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FEM Analysis

FEM Analysis

FEM Analysis

(OP)
Hello all,

I've a problem with the definition of a uniform torque load on a simple beam element. The element type is the b31os (the one that consider warping).
It's possible to define a line load but only on displacements degrees of freedom.But I'm trying to apply a rotational force per unit length in torsion analysis of open section.

The section is an I-SECTION and is not defined with shell elements.

Thanks

RE: FEM Analysis

It would be helpful if you would post the FEA program you are using.  Different programs treat applications in different ways.

RE: FEM Analysis

(OP)
Well,i'm sorry: the message was not so clear.

I'm using Abaqus/Standard, creating the structure by ABAQUS/CAE.
Is a clamped beam of 1m length and i want to apply an uniform torque.It's an open section, so warping effect on the cross-section has to be considered: the element type is the b31os.

In attachment the .cae file that I'm using.

The problem is really simple but i've difficulting with setting this kind of load (eccentric line load or uniformly distributed torque).

RE: FEM Analysis

Not familiar with Abaqus, but you could model outriggers off of the tube shape with point loads applied to the outriggers to mimic a torsion.

RE: FEM Analysis

(OP)
Yes I know, but the structural model that I need has to be loaded with a uniform torque, becaue my goal is to compare it with a model that I realized with Matlab.Point loads aproximations are not so useful to compare.

RE: FEM Analysis

I am using the LUSAS to model the behaviour of RC concrete beams with its Concrete Model 94 and Von-Mises applied for concrete and rebar elements, respectively.
From the results I have got so far, it has been found that, for the under-reinforced beams with small amount of tensile bars yielded, the LUSAS can give a reasonable result. For the over-reinforced beams with a great amount of rebar not yield, the LUSAS always generates a beam strength that is much smaller than the measured ones in the test.
Your advice on the causes for the above difference and how to minimise the gap between the LUSAS and tested results will be much appreciated

Regards

Ian   
 

RE: FEM Analysis

If you want to apply a uniform torque... you wouldn't want to apply a torque-per-unit-length, would you? Rather, you'd want to apply a torque at one end and constrain the other.

That said, I'm sure that ABAQUS is able to apply a torque-per-unit-length, but you may want to check in the ABAQUS forum if you need details on the methodology for applying the load (it's been a while since I've used ABAQUS, so I can't help you there).

Good luck.

RE: FEM Analysis

(OP)
Thanks,

I know is possible. M.Okeil and Sherif El Tawil, from Louisiana and Michigan, presented a paper in wich 18 curved box girder bridges have been analyzed by this kind of element. The problem is understanding how it works.

 

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