Thanks Brother. Lots of love. You helped us, we will help to grow your youtube channel more.

@Eng.tarekyoussef

Жыл бұрын

So nice of you! Thank you for your kind words and support.

really appreciate !

How is the process for the rotacional mode?, I mean mass matrix have the rotacional mass that's (a^2+b^2)*m/12 but if you use these values the magnitude diference between rotacional and traslational mass is too much, how i can compute de mass participation in rotacional if is that the case?

Thanks! Very helpful!

@Eng.tarekyoussef

Жыл бұрын

Glad it helped!

When you calculate the numerator of the participation factor (gamma_n in equation 8) at 0:26, it's not just mode shape transpose * mass; it's mode shape transpose * mass * influence vector. I didn't see you multiply by the influence vector in excel. You just calculated phi*m. How did you account for the influence vector? Also, one reason you might not be getting the same results from the software is bc a lot of the commercial software normalize the phi with respect of mass so phi^T*m*phi^1. You normalized it so that the largest magnitude is 1. I believe the participation factor is dependent on how you normalize the phi. Thanks!!

Hello, what means if the sum of effective modal mass calculated from Participation Factors table by ETABS is higher than rotational mass system?

excellent.

@Eng.tarekyoussef

Жыл бұрын

Thanks!

how can I check the Modal participation ratio output of ETABS in v 21.1?

Very Nice tutorial. But I want to know the very basic. Can you tell me, how can i calculate the lumped mass matrix and consistent mass matrix and stiffness matrix for a 3d space frame? Should i apply the gravitational load(such as dead load, live load, partition wall load etc) for calculating lumped modal mass matrix and consistent mass matrix? can you give me any link or anythng else that solved a full example ? Thanks.

@Eng.tarekyoussef

5 күн бұрын

To calculate the lumped mass matrix, consistent mass matrix, and stiffness matrix for a 3D space frame, you'll need to follow a systematic approach that involves understanding the physical properties of the frame and applying the principles of structural dynamics. Here's an overview that might help: 1. Lumped Mass Matrix Definition: The lumped mass matrix assumes that the mass is concentrated at the nodes. Calculation: - Identify the nodal points of the structure. - Sum the masses (such as dead load, live load, partition wall load, etc.) that are associated with each node. - Construct a diagonal matrix where the diagonal entries represent the lumped masses at each node. 2. Consistent Mass Matrix Definition: The consistent mass matrix distributes the mass over the entire structure, taking into account the shape functions used in the finite element method (FEM). Calculation: - Use the shape functions for the elements to distribute the mass. - Integrate these shape functions over the volume of the elements to construct the mass matrix. - This matrix is typically more complex and requires numerical integration. 3. Stiffness Matrix Definition: The stiffness matrix represents the relationship between the nodal displacements and the forces in the structure. Calculation: - Derive the element stiffness matrix using the material properties (Young’s modulus, Poisson’s ratio) and geometric properties (length, cross-sectional area). - Assemble the global stiffness matrix from the element stiffness matrices using the connectivity of the nodes. Applying Gravitational Loads For the lumped modal mass matrix and consistent mass matrix: - Gravitational loads (such as dead load, live load, partition wall load) are considered when determining the masses to be lumped at the nodes or distributed over the elements. - These loads influence the inertial properties of the structure and should be included in the mass calculations. #Resources • Structural Analysis by R.C. Hibbeler • McGuire, Gallagher, Ziemian, “Matrix Structural Analysis,” 2nd Edition, Wiley. • Ghali, A., Neville, A.M., Structural Analysis - a Unified Classical and Matrix Approach, Second edition, Chapman and Hall, London, 1978. • Sack, R.L., “Matrix Structural Analysis,” PWS-KENT, Boston, 1989. • McCormac, J.C., Nelson, J.K., “Structural Analysis-A Classical and Matrix Approach,” Second Edition, Addison-Wesley, 1996.

Thank you very much

@Eng.tarekyoussef

Жыл бұрын

You are welcome

Crack!!!

I do not understand the physical meaning of the negative participation factors in the Modal Analysis. I am confused the "modal" participation factor that often using on the force response analysis (or Harmonic in ANSYS). The M(odal) PF is related to the excitation location while the M(ass) PF is independent of the excitation location since it is only Modal Ansys. Can someone explain it to me?

What is the basis of taking square of model shape ( Mode shape (Sqr) * Mass matrix is done ). Its actually Mode shape transpose * mass matrix * mode shape isn't it .

wow this is the best i sub to you

@Eng.tarekyoussef

3 жыл бұрын

Thank you

Excellent videos, does modal mass participation ratio different between nonlinear and linear analysis,does sheet "nonlinear" have video? , thanks

@Eng.tarekyoussef

2 жыл бұрын

Yes, the modal mass participation ratio of linear and nonlinear model are different because the stiffness of structure is different in both models

Please in tables extracting from etabs of modal participating factor how i can control in modal mass ??

@Eng.tarekyoussef

3 жыл бұрын

In order to obtain the same value of the modal participation factor as ETABS you need to normalize the modal mass to be equal to one (Mn=1). Please check the book of dynamics to know how to normalize the modal mass.

@aliwael8126

3 жыл бұрын

@@Eng.tarekyoussef please i want to contact with U can i get your FB acc ?

@aliwael8126

3 жыл бұрын

@@Eng.tarekyoussef ???

@Eng.tarekyoussef

3 жыл бұрын

facebook.com/tarek.youssef.1481

OW TO COMPUTE IF THER IS COUPLE TRANSLATION CONTRIUTION IN MODE SHAPE

@Eng.tarekyoussef

Жыл бұрын

When we have a translational-rotational coupling in one of the modes, we need to multiply the modal quantities obtained from that mode (modal participation factor, modal mass participation ratio) by the "Modal Direction Factors". The Modal Direction Factors can be obtained from ETABS from Display ==> Show Tables ==> Structure Output ==> Modal Information ==> Modal Direction Factors. Check this link for more info regarding The Modal Direction Factors wiki.csiamerica.com/display/etabs/Direction+factor#:~:text=Answer%3A%20For%20each%20mode%2C%20modal,factors%20therefore%20sum%20to%20100.

Tarek I really love this. Can you comment when you see a participation factor (PF) less than zero, can you say what does that physically mean? Perhaps we don't care, and just look at the magnitude, right? I understand the Modal Effective Mass is the PF^2 so perhaps that is correct. Can you comment for me?

@Eng.tarekyoussef

3 жыл бұрын

The values of the participation factor (PF) depend mainly on how the mode shapes are normalized. Therefore it does not matter if you get a small or large value of PF because it is based on how mode shapes are normalized. Also, I believe that PF does not have a physical meaning, and we just need PF to compute other response quantities like the modal mass participation ratio (MMPR). The MMPR shows the participation of each mode in the total response which is important to know. Lastly, the Effective Modal Mass (Mn*) = (PF)^2 if the modal mass (Mn) is normalized to be equal to one. I hope I have answered your question.

Great work, Can you provide an email address in order to contact ? Thank you in advance.

@Eng.tarekyoussef

3 жыл бұрын

tarek.y.m1@gmail.com