Time Hystory Analysis
Time Hystory Analysis
Hello,
I am trying to model a simple plane frame with 3 spans and 5 story under a specific Time History motion.The problem is that the analysis does not finish the number of steps it is required to do.I tried refining the model to discover possible errors in modeling the frame but now i seem to have reached a dead end. Any suggestions?
I am trying to model a simple plane frame with 3 spans and 5 story under a specific Time History motion.The problem is that the analysis does not finish the number of steps it is required to do.I tried refining the model to discover possible errors in modeling the frame but now i seem to have reached a dead end. Any suggestions?
- seismosoft
- Posts: 1271
- Joined: 06 Jul 2007, 04:55
Re: Time Hystory Analysis
Hi,
The reasons could be multiple; error in the model assemblage, mistake in the loading definition, attainment of structure's capacity, etc.
For example:
- have you run eigenvalue analysis to check that the model geometry, mass and stiffness are as expected?
- have you run pushover analysis to check that the horizontal capacity of the model is adequate?
- have you checked for the possibility of the structure being reaching collapse under the earthquake input motion you specified (e.g. activate relevant performance criteria checks, check interstorey drifts, etc)?
- and so on, and so forth..
Seismosoft Support
The reasons could be multiple; error in the model assemblage, mistake in the loading definition, attainment of structure's capacity, etc.
For example:
- have you run eigenvalue analysis to check that the model geometry, mass and stiffness are as expected?
- have you run pushover analysis to check that the horizontal capacity of the model is adequate?
- have you checked for the possibility of the structure being reaching collapse under the earthquake input motion you specified (e.g. activate relevant performance criteria checks, check interstorey drifts, etc)?
- and so on, and so forth..
Seismosoft Support
-
- Posts: 124
- Joined: 06 Jan 2010, 05:34
Re: Time Hystory Analysis
Dear SeismoStruct Developers
I have encountered the same problem regarding to termination of Dynamic time history analysis under KOBE ground motion.
I have two different models:
1) One 8 Storey, 3 Bay RC frame.
2) One 8 Storey, 3 Bay RC frame with retroffited frp confined connections in beam-column joints.
First model (without retroffited joints) goes and finishes finely under Dynamic time History analysis.
But, and unfortunately the second model (with retroffited joints) terminates under Dynamic time History analysis prematurely.
These two models are exactly the same. The only difference is, columns and beams in the second model are wrapped in frp for 50 cm. In order to model the frp wrapped sections I have applied con_frp material and for the remaining beam-column elements I have applied con_cc.
I have already ran adaptive pushover and eigen value analyses on the second model with frp confined joints and it worked fine. But everytime I run Dynamic time History analysis it terminates prematurely.
I have encountered the same problem regarding to termination of Dynamic time history analysis under KOBE ground motion.
I have two different models:
1) One 8 Storey, 3 Bay RC frame.
2) One 8 Storey, 3 Bay RC frame with retroffited frp confined connections in beam-column joints.
First model (without retroffited joints) goes and finishes finely under Dynamic time History analysis.
But, and unfortunately the second model (with retroffited joints) terminates under Dynamic time History analysis prematurely.
These two models are exactly the same. The only difference is, columns and beams in the second model are wrapped in frp for 50 cm. In order to model the frp wrapped sections I have applied con_frp material and for the remaining beam-column elements I have applied con_cc.
I have already ran adaptive pushover and eigen value analyses on the second model with frp confined joints and it worked fine. But everytime I run Dynamic time History analysis it terminates prematurely.
- seismosoft
- Posts: 1271
- Joined: 06 Jul 2007, 04:55
Re: Time Hystory Analysis
quote:Originally posted by fakharifar.mostafa
Dear SeismoStruct Developers
I have encountered the same problem regarding to termination of Dynamic time history analysis under KOBE ground motion.
I have two different models:
1) One 8 Storey, 3 Bay RC frame.
2) One 8 Storey, 3 Bay RC frame with retroffited frp confined connections in beam-column joints.
First model (without retroffited joints) goes and finishes finely under Dynamic time History analysis.
But, and unfortunately the second model (with retroffited joints) terminates under Dynamic time History analysis prematurely.
These two models are exactly the same. The only difference is, columns and beams in the second model are wrapped in frp for 50 cm. In order to model the frp wrapped sections I have applied con_frp material and for the remaining beam-column elements I have applied con_cc.
I have already ran adaptive pushover and eigen value analyses on the second model with frp confined joints and it worked fine. But everytime I run Dynamic time History analysis it terminates prematurely.
Desr Mostafa Fakharifar,
Apologies for the delay in responding. Please send us the models in question so that we can look into the matter (if still pending).
Seismosoft Support
Dear SeismoStruct Developers
I have encountered the same problem regarding to termination of Dynamic time history analysis under KOBE ground motion.
I have two different models:
1) One 8 Storey, 3 Bay RC frame.
2) One 8 Storey, 3 Bay RC frame with retroffited frp confined connections in beam-column joints.
First model (without retroffited joints) goes and finishes finely under Dynamic time History analysis.
But, and unfortunately the second model (with retroffited joints) terminates under Dynamic time History analysis prematurely.
These two models are exactly the same. The only difference is, columns and beams in the second model are wrapped in frp for 50 cm. In order to model the frp wrapped sections I have applied con_frp material and for the remaining beam-column elements I have applied con_cc.
I have already ran adaptive pushover and eigen value analyses on the second model with frp confined joints and it worked fine. But everytime I run Dynamic time History analysis it terminates prematurely.
Desr Mostafa Fakharifar,
Apologies for the delay in responding. Please send us the models in question so that we can look into the matter (if still pending).
Seismosoft Support
-
- Posts: 42
- Joined: 29 Apr 2014, 15:42
Re: Time Hystory Analysis
I've the same problem.
i'm getting the error "Unable to apply the next load step" .
Screenshot of the error message can be found here
https://drive.google.com/file/d/0B1zFr_ ... sp=sharing
Please check my model
https://drive.google.com/file/d/0B1zFr_ ... sp=sharing
i'm getting the error "Unable to apply the next load step" .
Screenshot of the error message can be found here
https://drive.google.com/file/d/0B1zFr_ ... sp=sharing
Please check my model
https://drive.google.com/file/d/0B1zFr_ ... sp=sharing
Re: Time Hystory Analysis
I wonder if you should check your input adeelfaisal. Your column has approximately one-tenth of the minimum allowed reinforcement according to most codes (I calculate 0.1% reinforcement in your column, most codes specify a minimum for columns of 1%) and the transverse reinforcement is also extremely light. I suspect that your column is failing and that is the reason the model stops around 30 seconds into the loading history. The model runs, the inelastic behavior is observed in the column, and your isolation link never enters an inelastic phase.
If I modify the column reinforcing, both longitudinal and transverse, the model runs fine for the entire duration of the applied loading.
I encourage you to examine your results carefully and remember that structural failure is a real possibility in models. Just because a model doesn't withstand the duration of the applied load, don't automatically assume there must be something wrong with the solution algorithm.
Once I get the column to withstand the applied load, I notice that the maximum column force is 85 kN, while the isolator you defined has a yield force equal to 500 kN. So, as modeled, the isolator does not serve the intended purpose. I wonder if you should also check your isolation parameters.
As a final comment, it seems highly unusual, to me at least, to model friction pendulum isolators as a Takeda link. But perhaps you have information which I do not. I am not an expert on this.
Best of luck adeelfaisal.
If I modify the column reinforcing, both longitudinal and transverse, the model runs fine for the entire duration of the applied loading.
I encourage you to examine your results carefully and remember that structural failure is a real possibility in models. Just because a model doesn't withstand the duration of the applied load, don't automatically assume there must be something wrong with the solution algorithm.
Once I get the column to withstand the applied load, I notice that the maximum column force is 85 kN, while the isolator you defined has a yield force equal to 500 kN. So, as modeled, the isolator does not serve the intended purpose. I wonder if you should also check your isolation parameters.
As a final comment, it seems highly unusual, to me at least, to model friction pendulum isolators as a Takeda link. But perhaps you have information which I do not. I am not an expert on this.
Best of luck adeelfaisal.
Tim Huff
Re: Time Hystory Analysis
HI
I have same problem. I am running IDA for 12 story RC 3D structure with 3 bays by 4 bays. When I am running the IDA in the first scale factor (0.1) it does not have any problem but for the second analysis after 5 sec it shows this error (Unable to apply the next load step. Analysis terminated
Total Analysis Time: 4h:4min:21sec)
Can you guys help me?
I have same problem. I am running IDA for 12 story RC 3D structure with 3 bays by 4 bays. When I am running the IDA in the first scale factor (0.1) it does not have any problem but for the second analysis after 5 sec it shows this error (Unable to apply the next load step. Analysis terminated
Total Analysis Time: 4h:4min:21sec)
Can you guys help me?
Re: Time Hystory Analysis
Hi sadraddin. Given the excessive length of time to complete the first analysis, the problem which should not be ruled out is simply that of a structure which is failing. Failure could be somewhere between 0.1 and 0.2 scale factors. I might suggest reducing the load by, say a factor of 5, and seeing if the same problem now occurs somewhere between 0.5 and 1.0.
Best of luck, sadraddin.
Best of luck, sadraddin.
Tim Huff
Re: Time Hystory Analysis
Thanks huftte for your quick reply. Could you tell me how to do that I do not how to reduce the load by a factor?
Thanks huftte
Thanks huftte
Re: Time Hystory Analysis
Well, let's see. When you apply your accelerograms, I assume you specify a factor, usually 386, for example, if the accelerograms is in g and the length units are mm. So, why not specify 193 for this factor instead of 386 to effectively reduce the loading by a factor of 2? That would be one way to do it.
Best of luck, sadraddin.
Best of luck, sadraddin.
Tim Huff