i have modeled the RC beam with simply supported BC and used concrete damaged plasticity model to account for the nonlinearities in concrete, i have got the frequency value for the case of beam under its own weight only, i want to add loads to it to get values of frequencies for cases.
i have used a static general step to define the added load, knowing that this step is before the frequency step, but the results of frequency are not even close to literature!
i'm attaching two models one without load which has a first frequency of 43.79 cycle/sec which is equal to 267 rad/sec , that is close to the value in literature, my problem is when i add the load in the other model, i added here for example 800lb =3558.577 on each hanger of the beam , cause the loading is applied on two hangers as shown below, the frequency is not even close, it's almost the same as the case without loading.
i have attached the paper "by Jerath and shibai" i'm getting information from to model
i have also attached the beam scheme noting i have used the reinforcment as in series 1
i have used a CDP model based on a python code attached here that is based on a paper by carriera and chu also attached !
can anyone help, please?
Hi Yasmeen
As far as I understood ur question, once u wanna do the modal analysis using Frequency option, the external loads are not assisted in the analysis and only the weight of the beam is playing the role.
If u wanna add external loads, the Modal Dynamic option is an appropriate case to chase ur target.
for more information see the link below.
plz let me know if further question is persisted.
Best Lucks
https://www.youtube.com/watch?v=PghCyHjViEk
Dear Yasmeen
can you send me your abaqus model to check it and do some trials.
best regards
Dear Khaled,
thank you for sharing, it is a good video! yes it is as you said.
but my loads are just static, do i have to use the dynamic modal analysis, i've seen the video , he has used this step to apply an impulse which is considered as a dynamic load, can i apply static loads in this step?
Regards,
Yasmeen
Dear Prof Rafaat,
i will send to you through email.
thank you so much :)
Regards,
Yasmeen
Dear Yasmeen,
As I recall, in Abaqus, adding loads on a structure would not affect the natural frequency of the structure. I am not sure but I think if you place a mass point on the structure equal to the load you ought to apply to the structure, the results will be more sensible. Since the added load belongs to the structure itself this time. Hope this would help you.
Good Luck!
well, thank you for your answer
it's good! but what you're talking about is if the stiffness of the beam was constant.
what i wanted to do is that when i added loads beam stiffness decreaseed because of damage and so on the frequency
i made it !
thanks to God and everyone who helped me :)
Regards
- Badges
- Science topic