Incremental Dynamic Analysis

03-Analytical/modelling capabilities
Post Reply
AObayedC
Posts: 1
Joined: 10 Apr 2021, 10:06

Incremental Dynamic Analysis

Post by AObayedC »

Hi there,

Is incremental dynamic analysis linear or nonlinear?

Sincerely,

Abu
huffte
Posts: 978
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
Contact:

Re: Incremental Dynamic Analysis

Post by huffte »

Nonlinear.
Tim Huff
obaidullah khan
Posts: 21
Joined: 11 Sep 2023, 14:24

Re: Incremental Dynamic Analysis

Post by obaidullah khan »

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?
huffte
Posts: 978
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
Contact:

Re: Incremental Dynamic Analysis

Post by huffte »

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.
Tim Huff
obaidullah khan
Posts: 21
Joined: 11 Sep 2023, 14:24

Re: Incremental Dynamic Analysis

Post by obaidullah khan »

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.
User avatar
z.gronti
Posts: 824
Joined: 16 Oct 2013, 08:14

Re: Incremental Dynamic Analysis

Post by z.gronti »

Dear obaidullah khan,

You should create different SeismoStruct projects to assign the different ground motions you want to.
Zoi Gronti
Seismosoft Srl.
Post Reply

Return to “03-Analytical/modelling capabilities”