I am doing a research on simulating the behavior concrete member reinforced with FRP.

I behavior of FRP material was defined by multilinear curve consisted of three points: (0,0), (Strain at rupture, stress at rupture), (Strain at rupture + 0.0001, 0).

After running the model, I found that some strain readings in FRP exceeded the strain at rupture, while the stress value did not exceed rupture stress.

I expected that the reinforcement bars will rupture when the rupture strain is reached, according, strain readings should not exceed rupture strain. However, this is not happening.

I am missing something or doing something wrong?

Thank you.

]]>I'm currently trying to reconstruct the example 1Dbeam_middleforced from Tutorial.Static3D. Can there be found a handwritten step by step tutorial for this example, or a similar example?

I'm not sure about the required steps to model this beam.

Thank you

]]>I am modeling adjacent beams with shear key in-between. after generating the mesh and during preparing running, I received

an error of " you don't have assigned Material 0 at Element xx".

I have checked for any orphan entity (line or surface not belonging to higher entity) and still no change. I have checked the materials assignment as well and made sure everything was assigned to a material, but still gives this error.

Thanks in advance.

]]>I am trying to model a beam with a notch (or a dapped end beam) and I'm modelling it as three separate macro-elements:

One macro-element for the section above the notch, one macro-element adjacent to that macro-element, and then one macro-element beneath that one. However, when analyzing the beam then viewing the principal strains in the post-processor, the strain appears to be discontinuous between the macro-elements as opposed to flowing continuously between them. For example, right at the interface of the two macro-elements, macro-element 1 might have a strain of -0.002, but macro-element 2 might have a strain closer to 0.

The contact is set to perfect connection between the macro-elements. Is there a specific reason this is happening?

Thank you!

]]>(i) I am using Atena 3D for modelling concrete composite slabs. I am using CC3Dnonlinear material model for modelling concrete. I would like to know the constitutive modelling adopted for CC3Dnonlinear material model under compression. In this regard, I referred Atene Theory manual section 2.2.4. It was mentioned in theory manual that the elliptical ascending part is given by equation 2.57. The notations used in the equation are not clear and it does not matches with Fig.2.21. Kindly clarify the same and also provide any published reference for the same.

(ii) Whether the material model CC3Dnonlinear uses equivalent uniaxial stress-strain law similar to sbeta model?. The notation used in Fig.2.4 are not matching with Fig. 2.21. Please clarify the same.

]]>I got an error: internal error during analysis monitoring: unspecified error

Internal error while reading results: Access violation at address 04CE50F0 in module 'A3Run_1.dll', Read of address 00000058.

Could you plz explain this error and suggest me a solution to solve it?

Thanks

I am currently using ATENA v5.6.1 and I would like to support a beam in only the negative z-direction, but allow it to be free in the positive z-direction. What is the best way to go about doing this?

Thank you in advance!

m

]]>This would help a lot for example for a parametric study.

Thanks in advance for your help!

Kind regards,

sizi

]]>I read in the Documentation that one can manually change the distance of master/slave connection and that this would be helpful to model a periodic boundary.

Still I dont quite know how to exactly model a periodic boundary. What are the steps?

Thank you in advance for your help!

Regards,

sizi

]]>I have several questions regarding this topic

1) First of all ragarding the modelling approach. As for one-way spanning slab a 2D moddeling approach over the height is appropiate, I wonder where the difference lies between the approach of using the material concrete and reinforcement for discrete bars and afterwards quadrilateral elements or using the 2D shell material (and discrete bars)?

2) At the beginning I am trying to model experimental tests from the literature to obtain some comparison possibilities. In some these not only the horizontal displacement was restraint but also the ends of the testing slab were fixed ends which means that the rotation was blocked. Within "define boundary conditions" there is the "rotation constraint for point/line" option, which is only applicable to 2D Shell or 1D beam elements. If I dont use the 2D shell material/element how can I block the roatation of the vertical line representing the height of my slab? Is it enough to block the hoirzontal displacement of the top and bottom ?

In addition I need to model a spring (horizontal displacement) in order to consider a neighbourfield (either point spring or line spring... depending on the results)

Are the conditions concering the same line for rotation and spring compatible?

Thank you in advance for your help!

]]>I am using ATENA 3D.

I read ATENA documentations and I did not find clear explanation on the spring definition.

As I understand, the spring materiel is defined by the stress vs relative displacement, and the slop is the stiffness of the spring. I hope that this is true.

could anyone tell me how the spring behavior is effected by its length and area or thickness. What would be the reference in practical application to define these values (length, area, thickness)?

Thank you.

]]>I'm trying simulate a reinforced concrete frame in atena GID (2D) with lateral displacement and vertical load.

I obtained any results similar with experimental tests. Now, i changed my model for fine mesh with the aim of obtain better the crack pattern, but my model stop before finish the simulation. Guess, that with fine mesh the stiffness is higher and maybe the convergence isn't very good. How could help this case.

Regards

Ingrid

I have some problems understanding the results / finding the error in the modelling for a simply supported RC-beam.

Structure: Simply supported beam with one load (modelled as displacement) in mid span (3-Point-Bending-Test). The beam has one reinforcement bar.

Element types: The Concrete is modelled as CCIsoBrick<xxxxxxxx> and the reinforcement bar as CCBarWithBond (as CCDiscreteReinforcementME defined/generated through nodes and embedded in the brick elements)

Load: The structure is analysed until the first two/three cracks due to bending appear (load equals then approx. 1.3-1.4 x Load_crack and is less than half of the ultimate limit load).

Depending on the mesh size, I get different crack patterns. The load-displacement-relation as well as the total crack width (sum of crack widths in longitudinal direction for the vertical position) follow the same trend (of course with jumps at different positions since cracks appear not at the same time). If I have a uniform mesh size in vertical direction and only one element in transverse direction, I get the expected crack pattern with the expected distance between the cracks. If I discretize the transverse direction with more elements or/and change the vertical coordinates to a non-uniform grid, the crack pattern changes in an unexpected way. Instead of a new second crack (at some distance from the first one in the mid span), the crack in the middle will “continue” cracking (increasing of its width and neighbour elements start cracking, even though the stress at the expected crack position is significantly higher).

The “problem” of the transverse discretisation can sometimes be solved by performing the analysis with more load steps. However, not in all cases: for the “initial” model, 10 load steps after the first crack are sufficient to achieve the expected crack pattern. For some transverse discretisations lead to the same crack pattern using 50-100 load steps, others do not start a new crack even if up to 1000 load steps are used (This depends also on the general size of one element, i.e. number of elements in vertical and longitudinal direction). However, due to having only one reinforcement bar, increasing the number of load steps seems reasonable.

For the problem of the vertical coordinates (e.g. changing [0 0.02 0.04 0.06 0.08 0.12 0.16 0.2] to [0 0.016 0.032 0.05 0.075 0.1 0.125 0.15 0.175 0.2] in the *.inp) I was not able to find a way of obtaining somehow the expected crack pattern. The ELEMENT INCIDENCES are still grouped in one ELEMENT GROUP.

Maybe someone of you saw up to here already the problem. According to previous threads in the forum, my mesh causes - obviously - some trouble, since the results vary a lot. In the documentation (troubleshooting etc.) I couldn’t find a solution, that’s why I have the following questions:

1. Do I have to take something additional into account when discretising the transverse direction?

2. Can elements in one ELEMENT GROUP have different sizes or do different sizes cause problems? (e.g. because of only one Jacobian per group is calculated when IsoBrick elements are used, …)

3. Sometimes I got also different results when the reinforcement bar is going through the element / is at the position where element edges are / is at the position where element vertices are. Can this also cause some problems or is this just some side effects from the problems above?

I am glad for any kind of hint what I can try next.

Best regards,

Marcel

I am trying to model my own simple rectangular prestressed beam (as the one in the examples provided BondCabel_injected), along with applying a surface load instead of a line load. When calculating the model in ATENA Studio the elements get squished or deforms into some crazy thing. Could you possible provide a reason for this?

Also, I cannot seem to figure out:

1. How to correctly apply prestressing to a cable.

2. How to correctly apply a surface load - when do I use a dummy material and when not; applying the dummy material to a surface entity that already belongs to another volume with a different material; deciding to apply Load Force for Surface or Load universally for surface.

3. How to load the support constraints, prestressing and surface load correctly into the interval data to get the correct output.

4. Whether I need to create fixed contact constraints between two concrete volumes. (If I were to model an I beam for example)

I am unable to find any documentation that is able to help me.

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