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# Civil Engineering/vertical component?

Question
thanks for past guidance
in the time history analysis
should we scale the vertical component as a horizontal component?is it necessary to do?
can you describe it for me?
regards

It is not common/usual to provide your study with vertical time history analysis simultaneously with horizontal analysis because in conventional building the effect of vertical component of ground motion is not very critical. But it is clear that when the vertical component get important you cant negelect it. For example if the building you are studying has long span cantilever components you are obligated to perform total multidirectional dynamic analysis. Then it depends on the study you are following.

Regards
BEH

---------- FOLLOW-UP ----------

thanks a lot
if we porpose which my building have above conditions(for scale of vertical component),in the seismic cods says which vertical component should Consideration by static load(Centralized force). how can i scale of the vertical component acc. in the time history analysis? is it as the same(horizontal component)? because in the seismic cods dont say about how to scale of vertical component in the T.H.A
regards

For sure you must use 3 or 7 set of accelerogram which can be adopted from PEER site. If so you would scale the horizontal accelerograms and the vertical so as to keep the proportionality of the PGAs similar to their real status. For example:

you choose manjil, tabas, naghan for your study. you should consider manjil x ,manjil y and manjil z suppose the manjil PGa in x direction is 0.75 g , y direction, 0.8 g and z direction .4g. After you scale the accelerogram set you must have for x direction a pga of alpha x 0.75 g , for y direction alpha x .8g and for z direction alpha x o.4 g . You must keep the aspect ratio of the accelerogram set.

Doing so help you to scale the vertical component in a realistic way.

Regards
BEH

---------- FOLLOW-UP ----------

thanks a lot .
to answer you says which the vertical component its non common or critical!
but in the near field Earthquakes it is important.you know which in this case vertical component is 1.5*horizontal!!
thanks a lot
regards

Near field situation is rare , but if it happens you should be more focused on it. Anyway the vertical time history analysis same time as horizontal one is not common because of the complicated situation in analysis but for research purposes you can try it.

Regards
BEH

Civil Engineering

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