Dear Ghanshyam

Obviously in order to consider seismic load you should assign masses to nodes and then you can use nonlinear time history method to analyze. Also you can use equivalent seismic load based on standards.

I. Hajirasouliha, K. Pilakoutas, H. Moghaddam, “Topology optimization for the seismic design of truss-like structures”, Computers and Structures, vol. 89, pp. 702-711, 2011.

In aforementioned article you can find some examples. 

Hi,

One of the simplest ways you can do this is by assigning the seismic loads at your truss joints as concentrated forces. The truss members and connections, like any other member, shall also be capable of resisting seismic forces and transfer them to the supporting members.

A truss analysis in SAP2000 with seismic forces assigned, will give you a good picture of how the members of trusses act when subjected to seismic forces.

Hope it helps. 

Dear Ali,

Thank you very much for your answer. 

Would you please share some research paper or material related to this. As I don't get exact meaning of "assigning the seismic loads at your truss joints as concentrated forces" Because seismic load is nonlinear load which change with time. 

Is it possible to solve this in MATLAB, as I don't have SAP2000 software  

Dear Ghanashyam Tejani sir,

Instead of SAP 2000, I have worked on the STRAP and MATLAB software for frequency, weight and deflection optimization of 25 bar 3d-truss problem. I had solved this problem using method of differential evolution. But, instead of seismic load, I had applied concentrated point load. But, I can suggest you, while assigning point load, assign it as a seismic load using weight module.

Yes it's possible to solve this problem in MATLAB. I am sharing my MATLAB file also. Have a look. But, its solved for concentrated point load. By doing some changes in it, that is applying some more conditions to loading, you will get your results.  

Also, sharing some useful papers. Have a look. Thank you.

Dear Mandar Pandurang Ganbavale ,

Thanks for your valuable suggestions and coding,

I have solved many truss optimization problems for size, shape and topology optimization with static and dynamic constraints under buckling. In all cases we are assuming static load at node but in seismic analysis load is changing with time. 

I would like to appreciate your answer, which will help me a lot.

If you got any research paper related to this kindly share.  And kindly share this Q to your group 

Thank you 

Dear  Ghanshyam ,

point forces applied statically in the hinges of the truss should simulate the maximum forces coming from the seismic oscillation of the truss. This could easily be obtained by means of a dynamical analysis of truss.

It would be useful if you would show a simple sketch of the truss and the dead loads (masses) applied, in order to  simply simulating the seismic forces: than It will be simple to give you more suggestions.

Sincerely, L.Nunziante.

Dear sir,

I could help you in the same but by using STRAP software only. I'll try to get in and will let you know till this weekend. 

Respected Sir,

Thank you very much for your valuable suggestions Dr. Nunziante. 

I think: Seismic oscillation is random vibration (highly nonlinear) and If we consider only highest magnitude at node to convert dynamic load to static load. I don't think assumption will show correct result. 

Yes Sir, I will upload some sketches to visualize this problem and with more detail.

I  like to appreciate your suggestions,

Thank you very much ones again 

Respected Sir,

Kindly see attached file, Here I tried to explain some of important points. 

Thank you

Dear Mandar Pandurang Ganbavale,

Thanks for you support. Please try 

If you are going to do a nonlinear time history seismic analysis of the truss, then your input loading is a time-history of the earthquake record acting at the 'base' of the truss (time vs acceleration). And the response of the truss is computed every second (or time step defined by the user) for the duration of the earthquake. I am not sure if MATLAB has this capability of analysis, or if it can incorporate nonlinearities for the nonlinear time-history analysis?

To do nonlinear time-history analysis, you need to use special  analysis software which can include nonlinear models and hysteresis models (e.g DRAIN-2D, ANSYS, etc).

Good luck.

Maybe you should formulate your question in a different form.

How to include accelerations and what reference frame choose?.

Earth (soil) is a massive object that controls de dynamic of the problem.

So, you can define your structure and and then force displacement in the supports as you can expect in a real cism. Even more. You can include a portion of soil in your model and contemplate shear and liquefaction.

In a FEM (displacements) model you do not need to introduce the forces (unknowns) but directly introduce the displacements.

I expect this will be helpful to you and. In spite of my English.

Dear Lisandro Rodriguez,

I am new to seismic analysis, so currently I can't formulate exact problem definition. I will consider your suggestions.

Thanks a lot 

Dear Dr Abbes Berrais,

Thank you very much, 

You are absolutely correct, Input loading should a time-history of the earthquake.

I have seen a research paper in which this matter is discussed, but This paper does not included how to assign this to structure.

If you have related materials kindly share.

Thank you ones again  

Article Topology optimization for the seismic design of truss-like structures

The input loading will depend on the method and software to be used in your analysis.

For example if you are going to use the SAP2000 program,  the ground motion (earthquake record) is  applied to all support restraints. SAP2000 uses d’Alembert’s principle to translate the time history into acceleration loads which are applied to structural joints. During formulation, since acceleration couples with mass, it is important that joints have mass. More info about time-history analysis and how to input acceleration loads are explained in the following link:

 https://wiki.csiamerica.com/display/kb/Displacement+time-history+record

https://wiki.csiamerica.com/display/kb/Displacement+time-history+record

Sir,

I just tried it. I don't know but It may work. Here I am attaching gmail link which includes some calculations in excels and STRAP model I made. Download it and just edit the forces in dynamic module as per you want. If possible mail me on [email protected], so that I can send you details whenever I will do the same in detail. Now I am working on other topics, so will not have time to do this lengthy process. Sorry. Please find attached files.

https://drive.google.com/folderview?id=0ByfUef9d0KQ7QU03WkZHZWo4cFU&usp=sharing https://drive.google.com/folderview?id=0ByfUef9d0KQ7RUNpMFN5bDRPZ28&usp=sharing https://drive.google.com/folderview?id=0ByfUef9d0KQ7dTlULXNGY3d3Qkk&usp=sharing

Dear Mandar Pandurang Ganbavale,

You can email on [email protected]

Thanks for your help

In my opinion, if you want perform elastic analysis, probably time history can be used in the optimization process, on the contrary it becomes an expensive method.

I suggest you to introduce static forces simulating seismic loads obtained by accounting the modes of vibration of the structure updated during the optimization process. Indeed, this is a widely used method for simulating in a more refined manner seismic loads through static forces.

Dear Sir,

I am new to seismic, if possible kindly share material related to static forces simulating seismic loads. 

Thanks for your valuable suggestions 

You can found many papers concerning "Adaptive Pushover Analysis", a method of seismic analysis of structures where, during a static analysis, lateral applied forces are changed on the basis of the modes of vibration of structures which change due to the inelastic behaviour.

In your case, the variation of the modes, which influence the distribution of internal forces in the members due to seismic loads, is mainly due to the variation of the shape of the structure in the optimization process.

Thanks prof. Grande Ernesto

Dear Ghanshyam

if you have the model , please send it to me  then I will do it for you.....but for your information my ABAQUS  version is 6.11  , so  6.12 and 6.13 can not be worked on  in my version.  my email is (  [email protected])

Dear Ghanshyam

Obviously in order to consider seismic load you should assign masses to nodes and then you can use nonlinear time history method to analyze. Also you can use equivalent seismic load based on standards.

I. Hajirasouliha, K. Pilakoutas, H. Moghaddam, “Topology optimization for the seismic design of truss-like structures”, Computers and Structures, vol. 89, pp. 702-711, 2011.

In aforementioned article you can find some examples. 

Dear Mohammad Reza Garoosi,

Thank you very much for your valuable suggestions.

I have done dynamic analysis of truss successfully in which I considered masses at the node. but I could not get how to do nonlinear time history method to analyze this. Please share more information about it.

Thanks for research paper, I started my investigation with this paper. This is good paper but I could not get how to assign equivalent seismic load.

Thanks ones again 

Dear Nazim Nariman,

I have model in MATLAB, Would it be OK

Dear Sadjad Gharehbaghi,

Would you please expand your Q?

Dear Dr Abbes Berrais,

Is it possible to do this in MATLAB?

Dear Sadjad Gharehbaghi,

Thanks dear, I will follow your suggestions.  

https://www.researchgate.net/post/Where_to_find_structure_analysis_for_Benchmark_Problems_in_Structural_Optimization

Dear Ghanshyam,

Its possible in MATLAB. STAAD Pro Graphical user interface(easy to user interface) would have been much better for topology, size and shape optimization. Not only dynamic load, dead load, live load and wind load must considered in optimization.

Ashish