Hi there,
Is incremental dynamic analysis linear or nonlinear?
Sincerely,
Abu
Incremental Dynamic Analysis
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- Posts: 24
- Joined: 11 Sep 2023, 14:24
Re: Incremental Dynamic Analysis
hello
I have two questions regarding NLTHA/IDA Parameters:
1) what is logic behind assigning the curve multiplier value in NLTHA OR IDA. As I have seen 4 to 5 sample models in seismosoft forum having dynamic analysis containing value of curve multiplier=0,1.0,0.4,1.2695,9.81 etc.so can you explain the basic criteria or logic behind in selection of this value.by the way curve multiplier option lies at NLTHA/IDA==>Applied Load==>Nodal Load==>curve multiplier/value?
2)what is criteria in assigning the scaling factor values(start scaling factor, end scaling factor, scaling factor steps) in START-END-STEP in IDA?
I have two questions regarding NLTHA/IDA Parameters:
1) what is logic behind assigning the curve multiplier value in NLTHA OR IDA. As I have seen 4 to 5 sample models in seismosoft forum having dynamic analysis containing value of curve multiplier=0,1.0,0.4,1.2695,9.81 etc.so can you explain the basic criteria or logic behind in selection of this value.by the way curve multiplier option lies at NLTHA/IDA==>Applied Load==>Nodal Load==>curve multiplier/value?
2)what is criteria in assigning the scaling factor values(start scaling factor, end scaling factor, scaling factor steps) in START-END-STEP in IDA?
Re: Incremental Dynamic Analysis
The curve multiplier depends on the units used in your accelerogram input and the units valid in SeismoStruct. Typically, an accelerogram is input with units of g. A typical unit in SeismStruct is cm/sec/sec. For this example, the curve multiplier would need to be 981 to convert the input accelerations in the input file from g to cm/sec/sec. You will need to determine the appropriate multiplier for your case.
Also note that many times, you will want to scale the accelerogram in accordance with governing specification modification to match the design response spectrum at a particular project site. This provides another factor by which the curve multiplier needs to be adjusted, in addition to the unit compatibility multiplier.
For IDA, the scale factors are determined by you, the user. It depends on the analysis you are doing. If the input curves are design curves, then you might want to use, just as an example, values ranging from 0.25 to 1.25 to examine the structural behavior at increasing levels of input. If you were only interested in behavior up to the design loading, then your upper limit would be 1.0. So the range of scale factor is up to you the user and depends on the goal of your analysis.
Also note that many times, you will want to scale the accelerogram in accordance with governing specification modification to match the design response spectrum at a particular project site. This provides another factor by which the curve multiplier needs to be adjusted, in addition to the unit compatibility multiplier.
For IDA, the scale factors are determined by you, the user. It depends on the analysis you are doing. If the input curves are design curves, then you might want to use, just as an example, values ranging from 0.25 to 1.25 to examine the structural behavior at increasing levels of input. If you were only interested in behavior up to the design loading, then your upper limit would be 1.0. So the range of scale factor is up to you the user and depends on the goal of your analysis.
Tim Huff
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- Posts: 24
- Joined: 11 Sep 2023, 14:24
Re: Incremental Dynamic Analysis
hello
can any one can guide me about how to apply time history nodal loading...bcz i have to apply total of 11 ground motion files, each file containing 2 GM which will be apply in both (X,Y) direction so total of 44.but after defining load curves and Time-History stages in time-History Curves section, when i go for Applied loads section and define nodal load for each and every GM file in both x and y direction, and then go for run the analysis software gives error that "nodal load already define in x,y direction"....its mean software is taking nodal load only for 1st file not for others.so now how i can apply my total of 22 GM in both x and y directions in nodal loads category.
can any one can guide me about how to apply time history nodal loading...bcz i have to apply total of 11 ground motion files, each file containing 2 GM which will be apply in both (X,Y) direction so total of 44.but after defining load curves and Time-History stages in time-History Curves section, when i go for Applied loads section and define nodal load for each and every GM file in both x and y direction, and then go for run the analysis software gives error that "nodal load already define in x,y direction"....its mean software is taking nodal load only for 1st file not for others.so now how i can apply my total of 22 GM in both x and y directions in nodal loads category.
Re: Incremental Dynamic Analysis
Dear obaidullah khan,
You should create different SeismoStruct projects to assign the different ground motions you want to.
You should create different SeismoStruct projects to assign the different ground motions you want to.
Zoi Gronti
Seismosoft Srl.
Seismosoft Srl.