PUSHOVER ANALYSIS

[SASO]

Dear huff and zoi
Thank you for replying ,I know that I ask a lot questions?,but excuse me i am new user,i done what are you suggested but still not working with me, but ihave one more question can i run the model without using the performance criteria tab?

[z.gronti]

Dear SASO,

The performance criteria have been inserted in the program for users' convenience in order to be capable of identifying the instants at which different performance limit states are reached. It is not a prerequisite for the analysis. You may successfully run the analysis without any performance criterion assigned.

[SASO]

dear zoi ,
may i didn't clear in the question .
what i meant if you didn't use the performance criteria ,the shape of curve (capacity curve) is different completely if you used
Thanks for following
saso

[huffte]

Hi SASO. In the performance criteria, you can tell the program to stop, pause, or simply give notification when the criteria are met. It sounds as though you have selected the 'stop' option. This would be one explanation of why the appearances of results plots are different. If you change to the 'notify' option an re-run, does the curve look as expected?

[SASO]

dear huff
i didn't use option "stop" i used "notify".
the point of failure didn't show to me ,unless i specify the criteria and sstrut is unable to apply the load
if i didn't use the criteria , i model is run until the end ,but there is no failure point, my supervisor advised me to increase the values of material properties ,where the scope of this work is verification of this results and i didn't seek to be identical, i tried to increase the values step by step ,until i reached to this and i didn't want far from the range that mention in the paper
the material properties i used fcu=42,5 MPA tensile strength in case of concrete =3.31 MPA,fy =530MPA ,E=240000 MPA , taking strain hardening =0.03 ,and fracture/buckling =0.15
so if you can or any body else to check the model and run it to achieve a desired result and tell me
i will be grateful ,i must delivered this result the next week so i needed it so badly
saso ,

[SASO]

the link of model
https://www.dropbox.com/s/11nz8p2ym6f3i ... 5.spf?dl=0

[huffte]

Hi SASO.

I am curious as to why you have selected reinforced concrete t-sections for your beams, while the dimensions are such that there are no flanges? Why not just use a rectangular section? I am uncertain as to whether or not a t-section with dimensions specified such that there are no flanges would create problems or not.

I cannot reproduce the behavior you describe. However, if I change the element types to inelastic force based instead of plastic hinge elements, I can get the results to detect the failure criteria.

[SASO]

dear huff
i wonder , if you mean with "get the results to detect the failure criteria." which i specified in the model or that in the paper
,secondly , using infrm FB didn't allow to me to define plastic hinge
Generally, i used rec. sec for beam and change element class to infrmFB ,and model stopped again
if you didn't mind could you resend to me the modified model that you done? and revision if
1- material type is closer to material used in paper
2- the limit of performance criteria is correct , i notice that changing in the values of criteria Significantly affect on the shape of pushover curve
the attached pic . for comparison for analytical(sap) and experimental
thank you
saso

[huffte]

1. If you know the material strengths, you cannot expect to obtain realistic answers by arbitrarily changing them. This is nothing more than playing with numbers. The paper clearly presents the actual strengths and these should be used in your model.

2. As I said previosuly, your beams have no flanges. The paper clearly sates the slab thickness is 100mm. You will have to come up with your own rules for how much of the slab to consider effective as aprt of the beam. I somewhat arbitrarily assigned an effective width equal to 600 mm, which amounts to 225 mm of slab on each side of the beam.

3. With these adjustments I get a load factor of 0.98, which wehn multiplied by your applied load of 292 kN, gives a load of 287 kN.The paper reports a base shear capacity of 291 kN. I would say that is very close.

4. I wonder why you try to push the sttructure to a roof displacement of 300 mm. The capacity in the paper is about 250mm. Maybe 275 mm would be a better target?

[huffte]

5. The displacements also appear to agree in essence with the results in the paper, though I see you are having trouble predicting post-yield behavior all the way back to zero load. I am not sure you could expect to capture this behavior without special modeling strategies such as those adopted in the paper.

6. Are you certain that you have all of the load included in your model? Do you have the frame weight plus the slab weight plus the added 0.54 Tonnes at each floor. You should double-check this becasue the gravity loading on the frame has a lrage effect on column capacities.

7. You have applied your additional loading (permanent) to only the x-direction beams. Certainly this affects the capacity of your beams as they are over-loaded under permanent load.

So, in summary SASO, to match experimental results requires a lot of attention to detail and a lot of hard work up front. I encourage you to continue tweaking some of your modeling assumptions and to abandon trying to match experimental results by arbitrarily changing known parameters.

Best of luck, SASO. It's an interesting project you have.