Dyna5 Section 7.1

7.1 General Keywords

Data are input into the DYNA System using a keyword-oriented procedure. A keyword is used to indicate that a particular collection of data is being input. The DYNA system is quite flexible on its data format on input. The user selects the keyword by clicking on the appropriate box then inputs the data associated with keyword. The only limitation on the input that exponential format must not have a blank space between the 'E' and exponent. Examples 1.0E9 correct 1.0E09 correct 1.0E 9 incorrect PROBLEM DESCRIPTION The following pages outline the various keywords used to describe the problem to the DYNA system. PROBLEM TITLE The problem may be given a title using the TITLE keyword as follows: TITLE problem title (80) character maximum) The title is used on the printed output of DYNA. The limitations on the title are: (1) The first character of the title must be alphabetic (i.e. no digits) (2) The title must not contain equals (=), commas (.) or dollar sign ($). DATA ECHO DYNA will generate an echo indicating the interpretation of the input data. This echo may be terminated by the keyword: NOECHO GRAVITATIONAL CONSTANT The gravitational constant is entered using the keyword: GRAVITY The dimension of the gravitational constant must be consistent with the dimensions of the other input data and determines the dimensions of the output, e.g., with gravity = 32.2 ft/sec2 the displacement amplitudes of the response are returned in ft; with gravity = 9.81 m/s2 the displacement amplitudes are returned in m. Amplitudes of rotations are always in radians. FREQUENCY UNITS The default units for frequency are rad/s. The program also supports the use of input and output frequencies in Hertz (cycles per second) and rpm (revolutions per minutes). To indicate to the program the units of input and output frequencies the optional keyword FREQUENCY may be used as follows: FREQUENCY=RAD/S (DEFAULT) OR

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FREQUENCY=HERTZ OR FREQUENCY=RPM Notes: 1. The LOAD option RANDOM (SEE SECTION 7.4.3) IS ONLY ALLOWED UNITS OF rad/s. 2. The plots of the stiffness and damping constants that are produced by the GRAPH utility would always use RAD/S for the frequency axis, irrespective of the units used in input and output. The program handles such transformation of units internally. Inclusion of LENGTH, FORCE AND MASS UNITS IN THE OUTPUT FILE By default, DYNA does not include any units in the echo of the input data or the results. To indicate that a given set of units is to be used in the output file the following optional keywords may be used: To include force units use the keyword: LENGTH=length units To include force units use the keyword: FORCE=force units To include mass units use the keyword: IOMASS=mass unit where Length units = characters to be used for length units. The maximum length is 2 characters. Force units = characters to be used for force units. The maximum length is 3 characters. Mass units = characters to be used for mass units. The maximum length is 4 characters. Example: LENGTH=m FORCE=N IOMASS=kg or LENGTH=FT FORCE=lb IOMASS=slug Note: The inclusion of units specification for output purposes has no effect on the numerical values of the results which are governed by the gravity constant. The user must ensure that the input units are consistent and that they correspond to the chosen value for the gravity constant. PLOTTED OUTPUT A line printer plot of the response Curves for Harmonic, Transient, and Impact loading will be generated in the general output file by using the keyword: PLOT The default width of the plots is 70. In order to extend the width of the plots to 120 characters use the keyword: WIDE This keyword also extends the line width of file DYNFLEX to 112 characters in order to reduce the number of



lines in the file. The default length of the plots is 101 lines. In order to limit the length to 51 lines (1 page) use the keyword: SHORT In addition to the plot on the line printer, the program automatically provides the results of the response to harmonic and transient loading in the file named DYNAPLT. These files may be used with any special plotting software package available to the user to produce higher quality plots. DIMENSIONLESS RESULTS The response amplitudes calculated for Harmonic Loading may be non-dimensioned by using the keyword: DIMENSIONLESS Note : This command will produce dimensionless amplitudes that are equal to dynamic amplification factors and are defined by the following formulae: Constant force amplitude excitation: Dimensionless translations A= u0(w)/(u0(min)

Dimensionless rotations A = F0(w)/(F0(min))

Quadratic excitation: Dimensionless translations A = m/meexu0 =u0(w)/u0(8)

Dimensionless rotations A = I/(meeMi/Pi)F0

In the above formulae u0, f0 indicate true amplitudes of translation and rotation, respectively and min is the minimum frequency for which the response is calculated. For constant amplitude harmonic excitation, a zero frequency should be entered as the minimum in order to get the static displacements and the correct dynamic amplifications. For the flexible mat (option MATF) and the flexible cap (option CAPFLEXIBLE), the dimensionless vertical translations returned are calculated as the actual dynamic displacements divided by the static displacement of the circular rigid mat due to the sum of the vertical loads, EPi:

Ustat= Epi/((4Gr0/(1-v)) where r0 = squr(area/pi)

(for the CAPFLEXIBLE option , G and v are the value at the pile tip.) Note: If the dimensionless amplitude can not be evaluated because Ust is zero, true amplitude can not be evaluated because Ust is zero, true amplitudes are returned.

STIFFNESS AND DAMPING CONSTANTS The stiffness and damping constants are intermediate items in the DYNA solution of the response of rigid bodies but can be useful for separate analysis of elastic superstructures such as buildings supported by any of the foundations shown in Figs.1 to 4. A printout of the footing stiffness and damping constants is possible with the following keyword: MATRIX This keyword will instruct the DYNA system to output the constants stored in the Foundation Stiffness and Damping Matrices. These constants are refereed to the C.G. of the footing specified in the input and incorporate the mass of soil and piles. Because of the inertia effect of these masses, the stiffness constants can be negative, particularly for higher frequencies, soil Poison's ratio ->0.5 and massive piles. For the option RIGID-BODY, the



mass of the embedded footing is also incorporated in the stiffness and damping constants. NOTE: For the flexible mat (MATF option) and the flexible cap (CAPFLEXIBLE option), the keyword MATRIX is not applicable. TABULATION AND PLOTTING OF STIFFNESS AND DAMPING CONSTANTS For convenience, the stiffness and damping constants may be tabulated vs. Frequency and this also facilitates the input of data for any special plotting software available to the user. The tabulated stiffness and damping constants may be written to the general output file and/or to a separate file using the following keywords: TABULATE DYNSTIF The keyword TABULATE writes the tabulated values to the general output file. The keyword DYNSTIF writes the tabulated values to a file named DYNSTIF in the current directory. File for Plotting Stiffness and Damping using GRAPH Utility For the PC version of the program, the post-processing utility GRAPH may be used for plotting stiffness and damping constants vs. Frequency. At the end of a run the program echoed the following message: Generate files for plotting stiffnesses using GRAPH? (Y/N): If the user response with y, the program generates 10 specially formatted files with extensions .DGR (e.g. KVERTICL.DGR) in the current directory. These files are used by the GRAPH utility to produce plots of the stiffness and damping constants. For an explanation of the contents of each of these files refer to section 11.2. See section 10 of this manual for instructions on using the GRAPH utility. The generation of such plotting files is independent of the use of keywords TABULATE and DYNSTIF in the input file. NOTES: 1. The keywords TABULATE and DYNSTIF are not applicable for the flexible mat (MATF) option or the flexible cap on piles option (CAPFLEXIBLE). 2. If the file DYNSTIF or any of the (.DGR) files already exists under the same name in the current directory, it will be overwritten in the most recent run where the generation of such a file (or files) was requested. To save the tabulated stiffness results from a given run, copy the DYNSTIF file into a file under any other name of your choice. To save a stiffness or damping plotting file from a given run, use the post-processor utility option Save to save the data and the associated axes description. Damping Safety Factor If the applied frequency is close to the resonant frequency of the foundation or, in the case of foundations supporting a superstructure, close to the superstructure resonant frequency, the response strongly depends on the magnitude of the damping constants. To reduce the possibility of damping overestimation and thus response underestimation, an optional user specified safety factor may be applied to the damping constants using the keyword: SAFETY = S Where S is any positive number greater than 1.0 defined by S= C (calculated) / C (used) C (calculated) is the damping constant calculated from theory and C (used) is the damping constant given in the output and used in response calculation. The default value for S is 1.0.



Example SAFETY = 2.0 will divide the damping constant by 2.0. A value of s between 1.0 and 2.0 is recommended, with 2.0 suitable especially for pile foundations and deeply embedded foundations. Notes 1. The damping safety factor is not applicable to the flexible mat (MATF) and the CAPFLEXIBLE options. 2. The damping safety factor is not incorporated in the pile group stiffness matrices at the pile heads printed using the keywords FLEXIBLE, DYNFLEX, LATERAL OR DYNLAT (see Section 7.2.1). It is incorporated in the rigid pile cap matrix printed using keywords MATRIX, TABULATE and DYNSTIF. Figure 7.1: Notations for Pile Foundation Option with Rigid Cap (CAPRIGID)



Figure 7.2: Notations for Half Space Option a) Surface b) Embedded

Figure 7.3: Notations for Stratum Option

a) Surface b) Embedded

Figure 7.4: Notations for Rigid Body Option

Figure 7.5a: Notations for Composite Medium a) Surface b) Embedded



Figure 7.5b: Soil Profile and Notations for Composite Medium

i) Uniform Layer ii) Non-uniform Layer

Figure 7.6: Notations for Flexible Mat on Halfspace (Option MATf) and Pile Foundation with Flexible Cap

(CAPFLEXIBLE Option) Elevation

Plan



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Dyna5 Section 7.1