Structural Analysis - Science topic

Dear Eftekhar,

I have a suggestion, you can simply write OpenSees outputs to a text file using TCL commands, and then your MATLAB code can read the inputs written in that text file, doing it's processes and finally send back output by writing it in another text file,

Now you have to write a while loop in your TCL script that check Matlab output file for every n second (Based on the time that MATLAB prepares the results), if the MATLAB output for that specific time step exists, OpenSees can proceed to the next time step, and this process can continue until the end of analysis.

I hope this can work for you.

Regards

Abolfazl Najafi

Ken Wilber's Integral Psychological Maps are the most comprehensive

Please select all the nodes.

Dear Sir,

supervision consultant needs to verify the scaffolding design which considers all loads of concrete and labors, usually the scaffolding specialist to provide full calculations, this specialist works under the contractor umbrella, both of contractor and supervision consultant did not perform well

Invariably the loading on one storey building roof with access is only `1.5 to 2 kN/m2 . and this is uni-formally distributed load. But if you pile up load in a small area more than the failure load of slab with concentrated load then the failure is imminent. this failure load can be calculated using yield line theory or by Hillerborg Strip method.

If you have this kind of loading then keep your props intact before you finish roof top work

Get your data into excel and see if there will be marked inputs that show wrong annotations, which will not allow computing interface to run. Just a comma in place of a dot can through you off the rail. If this pulls through, then follow with Dr Emmanuel Arinze"s suggestion. I'm sure by the time you walk through these steps, you will overcome your challenge.

Good luck

It is not true that stress is not transmitting across the body. The results show a max von Mises stress of 1694 MPa, which is a sign of very localised stress singularity, perhaps at a sharp notch or edge. Such a high max value in the color band makes your whole body appear in blue color. Simply change the maximum scale value in your color band (e.g. 500 MPa).

Anoop Pillai

I think one way to do that is to get the results from the 2D model and assign them as the initial conditions to the nodes having the exact coordinates( in just two directions (x and y)).

En mi pais, hay material especial para tratar estos casos y otros mas; por ejemplo selladores, alquitranes, y otros.

You can write a APDL script to do that. You need to write a loop (*DO) on your nodes, read coordinates and apply your desired load as a displacement.

Rossana Fernandes Can you share the two Nastran models (.bdf)?

Long Chen first I tried to transfer the load directly to the structural solver yet the problem was that the feedback does not match with the input force, I had only one point, so I tried external data but I had a weighting error as I think I should also export the pressure coordinate but in that case we can not as I could not find any way how to export the pressure profile so I thought I may have an error in the simulation, I am doing it again.

I suppose something like that would be a future:

So its all about local materials, somehow tranformed in structural elements.

Its probably not, what you are looking for, but I m working on several ideas, how to construct partially underground cities. Let me know, if you are interesting in such stuff. best regards. J.

You can download the trial version and read user manual to practice the software.There are various online platforms offering a shirt term course for beginners like CAD Academy

Hi Murana Awad

Is it possible for you to share your data with me? I have some idea to solve your problem but I need your data.

I'm in touch by : ahmadi.v.1380@gmail.com

This blog may help

Perhaps this is due to the fact that the graphical method makes it possible to "see" the calculation. Psychological factor in choosing a method.

Dear Jatin,

Not always does a finer mesh result in a more exact solution. A mesh convergence study should always be performed to guarantee the descending trend of the error as the mesh size gets smaller.

Having this verified, yes, a finer mesh reduces the stiffness of the model. Because FE approximates the the PDE solution by forcing the element into specific modes of displacement which yields a stiffer element. But as the element size decreases, the FE solution converges to the analytical solution of PDE.

Eigenvalue can be physically interpreted as how stiff the structure is in the eigenvector direction. So it follows the same pattern as stiffness.

Is the data provided by Al Mouayed Bellah Nafeh of aluminum or stainless steel? As per the above draft, the yield stress is very high.

What would be the plastic strain-stress of structural steel ( Fe345, S275, S355)? Can I use the plastic stress-strain curve from material data provided by software SAP2000? Please make it clear. Thank you.

Dear Mostafa Shabani

Kindly check these papers:

we can write the minimum eccentricity = 12D/500 + D/30 = 0.057D, which has been taken as 0.05D or 0.05b as the maximum amount of eccentricity of a short column.

Typically chi^2 is expected to decrease upon refining further parameters, if the refinement is well-behaved. As chi^2 increases, this suggests that the refinement is NOT well behaved at that point. This suggests high correlation of the refined paramaters push the refinement into a direction where everything is even poorer (you should see than in the visible quality of the fit, which should get poorer.). It is typically a sign for high correlation of the refined parameters, which can well be for uvw. This is in particular the case, if other parameters are being refined which do the same on the calculated profile as uvw. This depends, of course, on the details of you profile function and its refined parameters, and the history of your refinement. Based on this, and in view of the quality of your refinement do YOU have the feeling that you should touch u, v, w? I do not mean chi^2 (The way how people deal with their counting statistics frequently makes this number meaningless, unfortunately), but I refer to the agreement between observed and calculated profile!

Yes you can

I think that's the best answer

Your interpretation is correct. The lateral loading due to wind and the moments due to rotating blades result in the problem.

use an FEA modeler or external model then connect it to your step

if you have a time-dept simulation, you can create a multiplyiting function with LIST_REEL and DEFI_FONC.

Franco

Dear Ali,

Columns can be broadly classified as short and slender columns based on their slenderness ratio. The slenderness ratio of a concrete column is defined as the ratio of its effective length le to its least lateral dimensions. The effective length is the unsupported length multiplied by a factor usually specified in the design codes depending on the end conditions of the column. Each code has its own criteria for classifying columns as either short or slender.

In this regard, I am attaching a thesis, where all the details have been given in more detail. I hope this will help.

Regards,

Pravin

This is a good question.

Faten Amer, Usually items not loading on their respective constructs are discarded. However, at times discarded items can be combined to make a new construct.

Robert has already given you advice regarding single items.

Can you share a little more information regarding the EFA, so that we could together see what you have done and how could we help you further? Information such as:

- Which extraction method are you using?

- How the number of factors was identified?

- and, which rotation method was employed?

There is a common misconception between PCA and EFA, and at times right parameters (above) not selected. Consider reading the following article, if not already done:

Costello, A. B., & Osborne, J. (2005). Best practices in exploratory factor analysis: Four recommendations for getting the most from your analysis. Practical assessment, research, and evaluation, 10(1), 7.

JASP is one of the latest software and it is free. If you need any assistance you can contact

Christian

thank you

yes i believe this is the problem

However, i am validating the Balanced scorecard which has 5 perspectives, under each perspective i could identify different constructs

actually i find it hard to delete or ignore any perspective

so i thought why not to split items depending on patient real experience items and the patient attitude items then to identify the constructs of each scale alone

the cfa and efa results became much better, also the constructs became more logic

my theory is that the 5 perspectives of balanced scorecard ( financial, customer, internal, external, and innovation and knowledge) experiences have effect on the balanced scorecard 5 perspectives images, which lead to patient satisfaction and loyalty.

so do you think it is not a good idea to plit the item based on dependent and independent items then to perform the construct validation for each separately?

Faten Amer , sample size it is not a problem at al in Bayesian Factor Analysis, see for example:

After the survey is completed..but it is better to increase the number of studied samples..so that the result will be bette

Rayleigh damping is defined as a linear combination, i.e.

D ='alpha M + beta K

also known as "Bequemlichkeitshypothese".

The mode shapes of the undamped system simultaneously decouples M, D and K. That means that all modes are damped by using this approach.

You might consider modal damping if only a subset of modes should be damped.

It should be rigid joint. However, it all depends on structure designer.

Steel

Yes we have to consider factor of safety depending on standards we are following and type of material and structure.

Which code are u using, this will assist in recommending suitable books and materials

Qamar Ul Islam Thanks, but that covers the first step, what I'm after is automatically insert these eigenvalues as a load in Riks which the second step

Hello Ophélie Martinie ,

Yes you should correct your T1 images before doing anything with your DWI. Here are my recommendations, please keep in mind that this varies from person to person but the below mentioned steps I have seen most common in diffusion imaging papers.

1. Fixing the orientation i.e. Moving into standard space or center your brain to (0,0,0). You can use FSL's fslorient2std command to re-orient.

2. Denoising

3. Gibbs ringing correction

4. Bias field correction

5. Skull stripping

In case if your T1 data is not in isotropic voxel you may also need to resample it too.

Dear Navin Ramroop

In general, ABAQUS is finite element analysis based software and generally used in research. However, STAAD and Etabs are used in analyze and design of structures in industry. So it depends on purpose.

Regards

I am sharing the one of the best article related to ABAQUS published in Elsevier. It might be help all.

Genikomsou AS, Polak MA. Finite Element Analysis of Punching Shear of Concrete Slabs Using Damaged Plasticity Model in ABAQUS. Eng Struct 2015; vol. 98: pp.38-48.

Regards

Dear Mohammed Lamine Mekhalfia

The only way to find the correct mesh size is by doing sensitivity analysis. In which we decrease the mesh size and point where results will not change by further decreasing mesh size is correct or optimum mesh size. All researchers follows this method. You can find many research articles of FEM.

I hope this will helps you.

Regards

I think Etabs, SAP, STAAD Pro, SCIA Engineer are best for analyse and design. However, Abaqus, Ansys, ATENA are best for research.

Here is a tutorial on eigenmode imperfections and newton raphson which may be helpful:

here is a tutorial on extracting the load displacement curve via python:

Dear Nithin Reddy Narala ,

I realized that you mentioned this question to Dr. , I haven't seen any answers or comment from him for about a year and half, I hope he is doing well. He got many experience in Ansys specifically Ansys APDL. We miss him a lot here in RG. Thank you so much for your kind email, it is my pleasure that my answers here in RG helped you in the past.

Going back to your question, I think Dr. Victor J. Аdlucky already provided a very good guideline and this is the only thing you can do, if you don't want to use any kind of coding for that.

You can do the following steps for calculating radial deformations.

1. Insert a Cylindrical coordinate system in the center of your geometry.

2. Insert a directional deformation contour. Select the surface you are interested in and adjust the coordinate system to the one you just made. Then adjust the Orientation to reflect "X Axis".

3. Extract the result for this contour. Extracted results show you the radial deformation which you can add/subtract it to/from the original dimension for calculating final dimension.

Also, You can do the same thing with Cartesian coordinate system, however, you need to extract the result for X, Y and Z direction and then calculate the resultant vector.

Hope this answer helps.

Thanks,

Hi Thant Zin Htun,

Some formulas can be found in sect. 20-21 of the book “Theory of Elasticity” by S. P. Timoshenko & J. N. Goodier.

Hi Bharat,

Setting the boundary conditions will only be part of the solution. In the case that the grids are dished, when heated they will expand in the direction they are dished. When they are flat, they could buckle away from the heat, towards the heat, or just become wavy or a saddle shape, depending on which bolt lets the grid slip first.

You should try adding a very shallow dish to your grid model, and make sure that it buckles in the same direction as that dish when heated. (i.e. the radius of curvature of the spherical surface goes down)

-Charles

What exactly is not clear?

WWER - water-water energetic reactor

THE ANSWER BY SPYROS ARVANTIS APPEARS REASONABLE.

Anargyros A. Karakalas Thank you for your reply.Very helpful information

The first one describes a single variable while the second case needs a couple.

Dear Spyros Arvanitis

I would choose solid, although the shell option works too.

Dear Mohsen, there is a rule of Thumb of Upadhyaya & Eryurec that says:

H= I * log2 N, where H is number of weights, I is the size of input vector and N is the number of trainning patterns. If you have 12 trainning patterns, and a input of size 1, you got only 3 weights. So its not possible to have a hidden layer. Hope it helps you.

References:

Hi

Modal analysis outputs can be found in the SM toolbox 6.0.4 instructions in the following sections:

74.29. ModalLoadParticipationRatios

74.30. ModalParticipatingMassRatios

74.31. ModalParticipationFactors

74.32. ModalPeriod

74.33. ModeShape

Best regards

Check this,

Hi Aidin,

Can you explain it very clear? So that I can try this method.

Hello Matheus,

in 2007, there was a whole special issue in Psychological Methods on formative variables that centered around the example of socio-economic status as a latent formative variable. It started with the very critical view by Howland and colleagues:

Howell, R. D., Breivik, E., & Wilcox, J. B. (2007). Reconsidering formative measurement. Psychological Methods, 12(2), 205-218.

The debate continued later with the same folks in the Journal of Business Research:

Wilcox, J. B., Howell, R. D., & Breivik, E. (2008). Questions about formative measurement. Journal of Business Research, 61, 1219-1228.

Best,

--Holger

Hi Spyros Arvanitis

This was my suggestion:

The formulation that you wrote is theta1 – theta2 /z1 – z2

So in your odb, for the theta you can get the rotation with Query/Probe values. Depending on which rotation you want you can extract UR1, UR2 or UR3. Also, for the value of the z1 and z2 you can get the COORD3 for those two points of C1 and C2. (don’t forget to active COORD in the step).

If you want to compute it through the whole cylinder you may need to write a python script to extract these values for all nodes and then compute it or plot it.

For moment formula, you need to take the normal stress component

Good work. I appreciate your research efforts and team work. Congratulations to all authors.

Interesting question!

In general and roughly speaking, for the same object (to be designed and/or tested=, there are many natural frequencies. Not all of them are equally important. Which ones will be important, depends on your problem.

Example 1- Frequency spectrum. If no external excitation are acting, the "free" or "natural" movement of your structure is the linear super-position of all the modes, meaning all modes participate. Generally, the lower the mode, the higher the participation. So you can say, low-frequency modes are "more important" in that sense.

Example 2- Resonance avoiding. Do you want to avoid vibration at a specific frequency? Then make sure your exciting frequency and the nearest natural frequency are sufficiently far from one another. This is called "separation margin" and should be 10-20% to design in a comfort zone, i.e. far from resonance. Resonance is when exciting frequency and natural frequency match. Although design engineers always try to avoid, test engineers know that it's not necessarily the worst-case scenario for your structure. If excitation magnitude is low, or acts close to a nodal point of your mode, or if there is enough damping to dissipate vibrating energy, the structure can operate in a resonant condition without too much pain.

Example 3 - If your problem is to compare natural frequencies on structures of different sizes, than you should define which order are you interested in, e.g. 1st bending mode. In general the smaller the structure, the higher is the mode.

I hope the three examples above help you a little bit.

Regards

Maurizio

Mehran Shahpari thanks, but I want to make a program that can easily check the analyzed structures without exporting the data to excel manually.

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I think in experimental work you measured displacement by millimeters while in program it's too small (may be in meter).

Furthermore, in experiment you had data only for the end of plastic stage while program provides post failure behavior. You need to match every units