Thread: Verification of modal analysis Results

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Re: Verification of modal analysis Results

Originally Posted by mecheil.edward.hanna
Hi Troy
Hi Z.G
this file show u step by step seismic load by ubc
But still scale factor without solution by robot
as I told before we can generate a new combination and multiply the seismic load by the required scale factor
Hoping it will be useful
http://www.4shared.com/file/QoEHcxiR/ToTroyAndZG.html

many thanks edward brother,

I will first review. I write again later. bye

ps: you have a big archive in 4shared. its suppper.. thanks.

best regards

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Re: Verification of modal analysis Results

Hi edward,

You've done a great work. was very surprised. Thank you very much. I now understand more clearly what they want to say.nobody could tell that so well. into the hands of health care.

1- my question is floor analiz method is rigid diaphram or only shell?
2- in our seismic standart have a criteria for peryot. N= number story of building
peryot not greater than Tx,Ty < 0.1N ( sample number story 40 then T max = 4 second.) this criteria at UBC yet? and why your bulding restraint simple restraint, not fixed. if fixed this base nodes then your period itself will decrease.

and you are lucky mans. cuz your code and standart exist in Robot and etabs. We are assigning for static lateral load shell is rigid. we are doing rigidity center lateral load. with hands calculate and define value for fx,fy. look we areuse turkish standart but not exist etabs and robot these. :/

many many thanks

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Re: Verification of modal analysis Results

Originally Posted by mecheil.edward.hanna
Hi Troy
Hi Z.G
this file show u step by step seismic load by ubc
But still scale factor without solution by robot
as I told before we can generate a new combination and multiply the seismic load by the required scale factor
Hoping it will be useful
http://www.4shared.com/file/QoEHcxiR/ToTroyAndZG.html

dear brother,

I want to say a few things.

first ..
we use scale factor in units ton.meter., but your definition is kip.in. is it mistake?
second...
we doing seismic loads analysis, if Vspec > Vstatic never reduce scale factor. because it will be wrong. but seismic (response analysis) are essentially. therefore we cant response spectrum scale factor in etabs and other programs. why do you this reduce? i m not understand, brother. is it right?

see later

best regards

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Re: Verification of modal analysis Results

Originally Posted by troy_the.best
dear brother,

I want to say a few things.

first ..
we use scale factor in units ton.meter., but your definition is kip.in. is it mistake?
second...
we doing seismic loads analysis, if Vspec > Vstatic never reduce scale factor. because it will be wrong. but seismic (response analysis) are essentially. therefore we cant response spectrum scale factor in etabs and other programs. why do you this reduce? i m not understand, brother. is it right?

see later

best regards
See,
when you open Etabs by default units will be kpi and you have to change to KN-M
when we run the model as a first time we put an accelarion of Spectrum diagram 9.81 m/s2
you can select any value you can put 1 2 or 3 as you want
We will say this is first scale factor Say FS1 ok
when we run analysis and we will know the natural period of building then we can get a static shear force
simply static shear force means the building is rigid i.e the the full energy of seismic will transfere to the building ok

Last step we have to callibrate the accelarion of seismic for response spec
this is what we say scale Factor
so the dinal scale factor of response diagram say SF2= SF1 x Vstatic/Vdyanmic
ok
But now you will be confiused and you ask how Vstatic< vdynaimc
it is not like that just we adjust the accelarion of spectrum curve
you get my point
Hoping it is clear

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Re: Verification of modal analysis Results

Originally Posted by mecheil.edward.hanna
See,
when you open Etabs by default units will be kpi and you have to change to KN-M
when we run the model as a first time we put an accelarion of Spectrum diagram 9.81 m/s2
you can select any value you can put 1 2 or 3 as you want
We will say this is first scale factor Say FS1 ok
when we run analysis and we will know the natural period of building then we can get a static shear force
simply static shear force means the building is rigid i.e the the full energy of seismic will transfere to the building ok

Last step we have to callibrate the accelarion of seismic for response spec
this is what we say scale Factor
so the dinal scale factor of response diagram say SF2= SF1 x Vstatic/Vdyanmic
ok
But now you will be confiused and you ask how Vstatic< vdynaimc
it is not like that just we adjust the accelarion of spectrum curve
you get my point
Hoping it is clear

edward,

if Vspec > Vstatic ( Vspec too large then Vstatic) then probably a mistake your model or specrtum analysis. values are usually very close. Please pay attention to this point. Have very different results, if the model is broken or not stabil. and dont reduce spec factor (if Vspec is great) absolutely. I know this very well.. please check again this point edward. usually spectrum analysis is essentialy in our solutions. equal lateral static loads for comparison. and have any period restrictions in your Code.

To use this equation. SF2= SF1 x Vstatic/Vdyanmic (have to be Vstatic>Vspec)

sorry my english.

best regards

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Re: Verification of modal analysis Results

hi friends,

i have a question. please look this screenshoot. whats the mean main mode number in seismic case.?

regards.
A.S.C.

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Re: Verification of modal analysis Results

troy_the.best,
Run modal analysis, then go to Results--Advanced--Modal Analysis. Look at columns name as Cur.mass UX, UY & UZ. Find maximum value in each column and look at number of mode for this value. And now you have main modes for X, Y & Z direction! Just type it in Combination Sign menu (your screenshot).

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Re: Verification of modal analysis Results

Originally Posted by romanich
troy_the.best,
Run modal analysis, then go to Results--Advanced--Modal Analysis. Look at columns name as Cur.mass UX, UY & UZ. Find maximum value in each column and look at number of mode for this value. And now you have main modes for X, Y & Z direction! Just type it in Combination Sign menu (your screenshot).
thanks romanich,

I had already guessed. then what we do? typing mode number and again analysis???? or what? in results will change anything ;??? i can understand this point.

best regards
falcoando_turkey
ASC

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Re: Verification of modal analysis Results

Yes, we run analysis again!

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Re: Verification of modal analysis Results

Originally Posted by troy_the.best
hi friends,

i have a question. please look this screenshoot. whats the mean main mode number in seismic case.?

regards.