Time History Method

ADVANCED TIME HISTORY ANALYSIS ANALYSIS METHOD  

******

Time History Analysis  Time history history analysis is an advanced method of dynamic dynamic analysis. It has an ability to incorporate incorporate harmonic forcing forcing functions that can be described by sinusoidal curves with a specied arrival time, frequency, amplitude and duration. Dene Time History Dialog: sed to dene the !orcing !unction !unction of a time varying load. "lic# Commands  Loading  Defnitions  Time History  or!ing "n!tions is selected or The $dd% button is clic#ed in the &oad ' Denition dialog found on the (eneral ) &oad ' Denition page. →

→

→

→

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

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. S#e!tr"m$

*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

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 : 69 *teel !e86

           0            0   .            4

           0            0   .            4

           0            0   .            4

4.00

4.00

PLAN

4.00

         0          0   .          4

         0          0   .          4

         0          0   .          6          1

         0          0   .          4

         0          0   .          4

0.40 X0.3

0.40 X0.3

0.40 X0.3

0.40 X0.3

ELEVATION

+,Creation o) -eometry:

1ew 5ro?ect !orceEF1

*pace !ile:

1e-t 3pen

Time history method

structure wiAard

nit

: &engthEmetre :

!inish.

"hange to !rame odels from Truss models



*elect Bay !rame and

double clic# on it. &ength C$long G DirectionE 6 2ach bayE8.9m Height C$long  Direction E6=.9m. 1o. of bays E8 2ach bayE8.9m idth C$long J Direction E 6 2ach bayE8.9m





 Transfer model ., (ro#erty$ "lic# (eneral

 "lic#

yes

 3F.

 5roperty  Dene 

$dd "lose.

Highlight 9.89 -9.>9 and select entire structure

to selected beam  /, S"##orts :

4ectangular DE9.89m JDE9.>9m

 $ssign  es.

  $ssign

 !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< M "D$5 M D$5 $rrival time

Time Csec

6

9

<

6

>

<

8

>

"lic# &oad case details 1umber 6

 $dd.  $dd.

&oading Type: Dead

 Damping

: 9.9

 Title: D&*

 $dd.

1umber <  Title: D&!&

&oading Type: Dead  $dd.

1umber >

&oading Type: *eismic

 Title: Dynamic

 $dd  "lose.

"lic# 1umber6 D&* *elfweight





!actor E+6

High light selfweight "lic# 1o.< D&!& !loor load

 $dd.  $dd.

  $ssign

to view

 $ssign.

 $dd.

pE+6< F17m<  range : ini.E8.9m a-E6=.9m  $dd.

"lic# Dynamic



$dd. *elfweight



 !actor: 6  $dd.



J !actor: 6



G !actor: 6  $dd.

 $dd.

!loor load pE6 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