model of lumped mass out of the frames

[abazvand]

hi all;
i want to model the lumped mass out of the frame in time hystory analysis so as to it is applyed on the structure non directly;so how can i model it?

[seismosoft]

We are not sure we understand what do you mean by "mass is applied to structure indirectly". In any case, we note two things:

- if you do not wish your mass to be transformed into structural loads, you need simply to disable the 'Automatically Transform Masses into Gravity Loads' option in the program settings

- if you really wish not to apply the mass on the structure, just assign it to a separate column by the side of your structure, and then connect the two using pinned links

Seismosoft Support

[abazvand]

hi seismo;
exactly,i want your "second note",but what properties and restraints do i have to apply in the case of column support and pinned links?

[seismosoft]

It all depends on exactly what you are trying to achieve, but, as we have stated already, we would imagine that you would pin such "external column" to the ground, and then would also pin the frame-column connecting arms.

Seismosoft Support

[abazvand]

hi;
i want to calculate the over strength factor of columns so we have to ignore the weigth of the structure in order to acheive 'Vmax','Vy' while doing the dynamic time-hystory analysis;
what kind of elements do i have to use for external column and connector element?

[seismosoft]

abazvand,

We have responded twice already to your question, and will do it one third time: we feel you should employ pinned elements.

Pinned frame elements can obviously be modelled in a myriad of ways, as described in the Help System/User Manual, and as discussed in many past posts in this Forum:

- truss elements
- elfrm elements with rotational end-releases
- infrm elements with rotational end-releases
- elfrm elements connected to link elements with zero rotational stiffness
- infrm elements connected to link elements with zero rotational stiffness

Seismosoft Support

[abazvand]

hi seisosoft;
excuse me for repetitive questions,i didnt know that.

[jackrussel]

Hi seismosoft,
I want to know about the situation of leaning column and beams that linked to it. in the below publication beams are rigid:

Hsiao, P., Lehman, D., and Roeder, C. (2013) Evaluation of the response modification coefficient and collapse potential of special concentrically braced frames. Earthquake Engineering & Structural Dynamics: Volume 42, Issue 10, August 2013, Pages: 1547–1564

which kind of modeling is true? with truss element... or a rigid pinned element?
thanks for your attention

[seismosoft]

Hi jackrussel,

As you will have imagined, it is not necessarily feasible for us to find the time to read and study scientific publications recommended by our users.

We also feel that it would probably be inappropriate for Seismosoft's Discussion Forum to feature reviews/critic of scientific publications.

We hence prefer to leave it to individual users to carry out such literature reviews and formulate their own opinions about the modelling options made by other researchers, as described in their papers.

Seismosoft Support

[jackrussel]

hi seismosoft,
thank you. I understand limitations. but I believe this is very important to classify the true methods for 2D analysis with seismostruct. you can find subject like this in opensees site.
http://opensees.berkeley.edu/wiki/index ... ment_Frame