A powerful computer program should be founded on advanced theory and be verified by tests and practice. The DYNAN program follows these guidelines. DYNAN is based on the improved Novak\’s method where a non-reflective boundary is formed between the near field and the far field to account for the mass of soil in the boundary. The program yields the dynamic response of both shallow and deep foundations under harmonic, transient, and random loadings. Such loadings can be produced by rotating or reciprocating machines, earthquake, wind, blast, sea waves, and other sources.
The foundations (or caps on piles) are assumed to be rigid, and all six degrees of freedom are considered as coupled. The foundation stiffness and damping constants are also returned for possible use in soil-structure interaction analysis.
The stiffness of the supporting soil along with damping constants needed for the analysis and evaluated in the program for surface foundations, embedded foundations, and pile foundations. Soil layering, a possible weakened zone around a foundation, and pile-soil-pile interaction are all taken into account.
The computational method has been applied to important engineering practice (Han, 1987, and Han, et al, 1999). To investigate soil-structure interaction, a series of dynamic experiments were performed on full-scale mat foundations (Han, 1989) and on full-scale piles (Han and Novak, 1989, 1992). The elastic wave energy from foundation vibration was dissipated in three dimensions as radiation damping. The soil is not a perfect elastic medium as assumed in the theory and the experiments showed that damping is overestimated in the computation. For practical purposes, the damping is reduced in DYNAN based on experimental results.
DYNAN can be used for the dynamic analysis under transient and random loading in the time domain. It also can be used for harmonic loading in the frequency domain. By means of a substructure method, the dynamic response of superstructure is calculated using a finite element program, such as SAP2000, and the stiffness and damping of foundation are generated using the DYNAN program.
LIST OF FEATURES
The program employed well-established analytical solutions for soil-structure interaction under dynamic loading condition.
The program can analyze four types of foundations: (1) footing on homogeneous half-space (half-space option); (2) footing on homogeneous layer (stratum option); (3) footing embedded in layered medium (multilayer option); and (4) deep foundation (pile option).
The program was developed based on the improved Novak\’s method and a non-reflective boundary is formed between the near field and the far field to account for the mass of soil in the boundary zone.
For practical design purposes, the foundations (or caps on piles) are assumed to be rigid, and all six degrees of freedom are considered as coupled.
The group effect of piles is accounted for by using the method of interaction factors in the DYNAN program.
In DYNAN, the harmonic excitation can be of two types: constant amplitude excitation, and frequency dependent (quadratic excitation).
The program accepts either S.I. units or English units.
DYNAN can be used for the dynamic analysis under transient and random loading in the time domain (see Han and Cathro, 1997). It also can be used for harmonic loading in the frequency domain.
The program generates the output data for each frequency of harmonic loads on the foundation.
The graphics menu allows quick observations of results contained in the output file.
The files of input data and output data are text based and may be directly accessed from within the DYNAN program, employing the user\’s preferred text editor or word processor.
A well-documented manual is provided with the relevant theoretical background and guidance to input screens.