I am Doing project on scale factor. i.e. base shear scale factor. in the manually calculation we dident use any type of 1st scale factor but in etanb 16 we use 1st scale factor as the Ig/2R. also i want to know that why matching is done in static and dynamic analysis.
depending on the code you are following; I.e. the IBC code, look at the equation for calculating the base shear, most probably the factor for base shear that will be multiplied by the weight W. In the scale you mentioned I is the importance facto, g is gravitaFiona’s acceleratio, R is the response modification factor. So, it seems that the ETABS wheb you enter the seismic parameters performs its computation for the full W, then multiply by the scale factor based on the input parameters.
In the case you define the seismic forces after calculating the story forces based on the equations, you put the scale to be 1.
thank you Mohammad Alhassan sir .. it is helpful for me. if you found any research papers on scale factor please send me it will be helpful for my research project.
First let us define the response spectrum curve. RS curve represents the plot of response acceleration with period. So if we have a SDOf system, simply we calculate the period of it and from the RS curve we can find the response acceleration. When we get the acceleration we can multiply it with the mass to get the base shear. But the problem if we do this without scaling, is that we design on the real values of the RS curve which is not economical. Therefore we rely on the structural ductility and accept a certain level of damage and this is why we divide on R. The more ductile the structure, the larger R we will get and the lower base shear to design for. On the other hand for "I", it represents the importance, the more important the structure, the lower damage we accept and therefore we magnify the base shear. Lastly, "g" factor, this one depends on the RS curve, as engineers -when creating the RS curves- they divide the acceleration on the ground acceleration "g". So the RS curve acceleration is normalized to the ground acceleration. But when we want to design we just multiply it with the ground acceleration to get the real value. However, if your RS curve is not normalized, you do not have to use "g".
Scale factor is Ig/R, not Ig/2R.
As we input values of I and R while defining load patterns for equivalent lateral load procedure(ELF). Unlike ELF in response spectrum analysis u should input these parameters(I & R) by using scale fctor to get inelastic demands.
Hello all dears
To do time history analysis in ETABS
I downloaded 7 acceleration records from the Peer site
and then I made the spectrum according to the rules and got the scale factors
I introduced it to Etabs software and did a time history analysis
but does not occur nonlinear hinges in beams and columns
I'm likely to make a mistake in scaling
when I Multiplied the acceleration in an extra g(=9.81) I find my goal. But I have to have a reason for my work
If I get a scaled acceleration that is correct and ready to use in Etabs
I can compare and find the problem.
please send me the scaled acceleration record that you used for time history analysis in Etbas.
Sincere thanks
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