Cyclic1D is a nonlinear Finite Element program for one-dimensional (1D) lateral dynamic site-response simulations. The program operates in the time domain, allowing for linear (Hughes 1987) and nonlinear studies. Nonlinearity is simulated by incremental plasticity models to allow for modeling permanent deformation and for generation of hysteretic damping. For analysis of dry as well as saturated strata, the finite elements are defined within a coupled solid-fluid (u-p) formulation (Chan 1988, Ziekiewicz et al. 1990). Dry and/or saturated soil profiles may be studied. In saturated cohesionless soil strata,
liquefaction and its effects on ground acceleration and permanent deformation are modeled. In this regard, the usermay wish to explore the response of a level ground site, or conversely to investigate the response of a mildly-inclined infinite-slope site. The Microsoft Windows-based in terface allows for: 1) convenient pre-processing (i.e., preparation of input data file), 2) initiation and execution of the computations, 3) display of the response (output), and 4) generation of an output report with the desired figures and relevant information. This interface is designed for simplicity, and is intended to be
intuitive and self-explanatory.