Time History Method

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ADVANCED

ADVANCED TIME TIME HISTORY HISTORY ANALANALYSIS YSIS METHODMETHOD

******

Time History Analysis

Time histo

Time history analysis is an advanced method of dynamry analysis is an advanced method of dynamic analysis. It has anic analysis. It has an

ability to incor

ability to incorporate porate harmonic forharmonic forcing functions that can be cing functions that can be described bydescribed by

sinusoidal curves with a

sinusoidal curves with a specied arrival time, frequency, amplitude andspecied arrival time, frequency, amplitude and

duration. duration.

Dene Time History Dialog: Dene Time History Dialog:

sed to dene the !orcing !uncti

sed to dene the !orcing !unction of a on of a time varying load.time varying load.

"lic#

"lic# Commands Commands→→ Loading Loading→→ Defnitions Defnitions→→ Time History Time History→→ or!ing or!ing

"n!tions

"n!tions is selected or The is selected or The $dd% button is clic#ed in the &oad ' Denition$dd% button is clic#ed in the &oad ' Denition dialog found on the (eneral ) &oad ' Denition page.

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Integration Time Ste#$

*olution time step used in the step+by+step integration of the uncoupled equations.

Ty#e$

This refers to the number of the type of functions.

Loading ty#e$

*elect the $cceleration, !orce or oment option to dene the type of functions being input.

Sa%e$

*elect this option to create an e-ternal le containing the history of displacements of every node of the structure at every time step.

"n!tion O#tions$

Dene Time * /loading type0

sed to specify a time history forcing function, where the loading type is that selected above. *pecify the values Time and corresponding !orce or

$cceleration. The time history function is plotted on the bottom of the dialog as data pairs are entered.

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C"r%e S&a#e$

*pecify if the harmonic function is a *I12 or "3*I12 curve.

re'"en!y or R(M$

"hoose !requency and enter circular frequency in cycles per second or 45 and enter revolutions per minute.

Am#lit"de$

a-. $mplitude forcing function in current units.

(&ase$

5hase angle in degrees.

Cy!les$

1o.of cycles of loading.

Ste# o) S" Di%$

"hoose the step option to time step of loading *ubDiv to sub divide a 678 cycle into this many integer time steps.

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*elect this !unction 3ption to provide spectrum parameters for your time history loading.

Time History 5arameters Dialog:

Time Ste#$

*pecify a solution time step to be used in the step+by+step integration of the uncoupled equations.

Dam#ing$

The following options are available for specifying damping:

Dam#ing+this is to be used for specifying a single model damping ratio which will be applied to all mode. The default value is 9.9.

CDAM( ; if a damping ratio has already been specied under "31*T$1T* based on the type of material in the structure, the value may be used

directly in time history analysis. "hec# this option for that purpose.

MDAM( ; we wish to utilise individual damping ratios for individual modes, that is achieved through the means of the D$5 option. The rst step to doing this is the specication of those individual damping ratios, as

e-plained under section .<= .> of the *T$$D technical reference manual and is done graphically from the command+dene damping menu. If this rst step has been completed, the instruction to utilise D$5 done by selecting this option shown above.

Arri%al time$

*pecify values of possible arrival times of the various dynamic load types. The arrival time is the time at which the load type begins to act at a ?oint or

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at the base of the structure. The same load may have di@erent arrival times for di@erent ?oint and hence all these values must be specied here. The

arrival time and time force pairs for the load types are used to create the load vector

needed for each time step of the analysis.

TIME HISTORY METHOD

Data:

*iAe of Building : 6<m - 6<m C> Bays each 8.9m Height of Building: 6=m C8 Bays each 8.9 m "olumn ' Beam siAe : 9.89m - 9.>9m

"oncrete >9 *teel !e86 4 . 0 0 4 . 0 0 4 . 0 0 4.00 4.00 4.00 PLAN

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ELEVATION 4 . 0 0 4 . 0 0 4 . 0 0 4 . 0 0 0.40 X0.3 0.40 X0.3 0.40 X0.3 0.40 X0.3 1 6 . 0 0 +,Creation o) -eometry:

1ew 5ro?ect *pace !ile: Time history method nit : &engthEmetre :

!orceEF1 1e-t 3pen structure wiAard !inish.

"hange to !rame odels from Truss models  *elect Bay !rame and

double clic# on it.

&ength C$long G DirectionE 6<m. 1o. of bays E> 2ach bayE8.9m Height C$long  Direction E6=.9m. 1o. of bays E8 2ach bayE8.9m

idth C$long J Direction E 6<.9m. 1o. of bays E> 2ach bayE8.9m 

$pply 

Transfer model  "lic# yes  3F.

., (ro#erty$

"lic# (eneral  5roperty  Dene  4ectangular DE9.89m JDE9.>9m

$dd "lose. Highlight 9.89 -9.>9 and select entire structure   $ssign

to selected beam  $ssign  es.

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!ront view "lic# support "reate 5inned $dd. Highlight support < 

*elect

node cursor and select bottom most nodes by windowing  $ssign to

selected nodes

 $ssign  es "lose.

De select the nodes and change to beam cursor.

0,Loading $

"lic# &oads ' Denitions Denitions  Time History Denitions  $dd.

Time history denition screen will appear. *elect Dene Time History 

Integration

Time stepE9.996>KK sec. Type 6 &oading Type  $cceleration

!unction option  !rom e-ternal le. !ile 1ame: 2L Data.t-t  $dd.

1ote: The 2L data.t-t le should be in the Time History problem folder only. 3therwise *taad pro will show error.

"lic# Dene 5arameter Time step : 9.9<  Damping : 9.9

M "D$5 M D$5

$rrival time Time Csec

6 9

< 6

> <

8 >  $dd.

"lic# &oad case details  $dd.

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Title: D&*  $dd.

1umber < &oading Type: Dead

Title: D&!&  $dd.

1umber > &oading Type: *eismic

Title: Dynamic  $dd  "lose.

"lic# 1umber6 D&*  $dd.

*elfweight   !actor E+6  $dd.

High light selfweight   $ssign to view  $ssign.

"lic# 1o.< D&!&  $dd.

!loor load pE+6< F17m< _{ range : ini.E8.9m a-E6=.9m}

 $dd.

"lic# Dynamic  $dd. *elfweight  G !actor: 6  $dd.

  !actor: 6  $dd.

 J !actor: 6  $dd.

!loor load pE6<F17m< _{ range : ini.E8.9m a-E6=.9m}

G range : ini.E9.9m a-E6<.9m J range : ini.E9.9m a-E6<.9m

(lobal G  $dd.

(lobal    $dd.

(lobal J  $dd.

Highlight *elfweight G  $ssign to view  $ssign  es.

Highlight *elfweight    $ssign to view  $ssign  es.

Highlight *elfweight J  $ssign to view  $ssign  es.

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(round motion $rrival Time :< sec Dened Types : 6.$cceleration

*elect direction G !orce $mplitude !actor : 6.<  $dd "lose.

"lic# &oad case details $dd $uto &oad "omb *elect &oad comb code:

Indian

code. *elect &oad comb category: (eneral structure (enerate loads $dd.

*elect &oad comb : 8,,=

&oad comb 8 6 6.< < 6.<9 &oad comb  6 6.< < 6.< > 6.<

&oad comb = 6 6. < 6. > 6. $dd.

"ommands iscellaneous  "ut o@ ode shape .

a-. 1o. of ode shapes: >9 C vary from < to >9 3#.

1, Analysis Ty#e:

5age control $nalysis75rint   ode shape  $dd.

"lic# post printDene "ommands $nalysis 4esults$dd"lose.

2,(er)orm Analysis:

$nalysis  4un $nalysis   view output le  Done.

3, Res"lt :

"lic# output icon. "lic# result.

• 2igen solution

• 5articipation !actors.

• $nalysis 4esults

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"alculated !requencies for &oad casesE>

5articipating factors ;4esult more than O9P 3#.

Time step E9.9< sec

1o. of ode shapes contribution is consideredE>9 Time Duration of Time history analysis E>8.6=9 sec. 1umber of Time steps in the solution processE6Q9K

a-. Base *hear G E+6.8<68K2R9.9< E+Q.=<O>O2+9=

JE+<.>=8=K=2+69 "lic# post processing. *elect &oad "omb 8,,= ode shapes ; odes 6,<,>

*elect Dene (roup name: 4oof

*elect Type: ode 3#.

1ow select the roof nodes. ou can see the Time+ $cceleration for various nodes on

data area.

(o to !ront view and select roof nodes. (o to side view ' see . (o to isometric view

select roof nodes ' see Time+$cceleration. Then select $ssociate 3#.

*elect (roups (6S4oof N (6  3pen. *elect the particular node. ou can

see the

Time+ $cceleration . then clic# time+ Displacement. *elect group (6S4oof

3pen.

*elect the node ' see the Time+ Displacement on data area .*elect deection node '

small scale ' view.

4esults Displacement  *elect scale select $cceleration  *ection

displacement

$pply.

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