The characteristics of earthquake ground motion have great influences on the response of structures to the earthquakes. Peak ground MOTIONS, duration of strong MOTIONS and frequency content are important characteristics of earthquakes, which are studied in this paper. The relation between peak ground acceleration, velocity and displacement have been taken into account and the effects of magnitude, epicentral distance and recorded duration of earthquakes on peak ground acceleration have been presented as graphs. The frequency content of ground motion can be examined by power spectral density of accelerograms. In this study the power spectral density of the records have been determined and normalized power spectral densities are compared. There are different formulas for the smoothed power spectral density function such as Kanai-Tajimi's model. In this study, comparing with Kanai- Tajim s formula, the extreme value model is suggested for the spectral density function. This model is evaluated for accelerograms on different soil conditions and the smoothed mean power spectral density function are determined for each soil groups. The central frequency and predominant period of earthquakes are also estimated. .

In this paper, an integrated computational procedure for the simulation of a two-phase flow, as well as floating and submerged body MOTIONS, is presented, based on a Volume of Fluid (VoF) - fractional step coupling. Two fluids are modeled as a single continuum, with a fluid property jump at the interface, by solving a scalar transport equation for the volume fraction. In addition, the conservation equations for mass and momentum. Are solved using the fractional step method. Based on the integration of stresses over a body, acting forces and moments are calculated. The strategy of non-orthogonal body-attached mesh and calculation of the MOTIONS at each time step, result in the time history of floating or submerged body MOTIONS. The motion simulation strategy is evaluated by using a cylinder water entry test case. To demonstrate the capability of the simulation, barge resistance is also calculated in two cases of fixed and free motion (2-DoF).All of the results are in good concordance with experimental data. and the present method can be extended for the full nonlinear-motion of ships in waves.

In specified limits of weather and sea conditions, the term optimum transportation is used to address maximum safety and crew comfort, minimum fuel consumption, minimum time underway, or any desired combination of these factors. Before defining such a goal function to optimize the transportation, one has to know about the ship reaction in waves. In other words, ship MOTIONS evaluation in different sea conditions is the base of ship routing.In this paper slamming rules as an important criterion in ship MOTIONS and its probability is investigated and predicted. By applying different motion's constraints, evaluation of ship MOTIONS is also applicable. Limitations in maximum vertical acceleration of bridge and maximum roll angle are considered as the main criteria and speed polar diagram is plotted according to such restrictions. This yields the regions with minimum risk of damage and maximum safety. It must be remembered that the general method presented here, is also applicable for other sea keeping criteria and all types of floating bodies.

In this paper, we study cyclic surfaces in E15 generated by homothetic MOTIONS of a Lorentzian circle. The properties of these cyclic surfaces up to first order are investigated. We show that, as it is shown in E5, cyclic 2-surfaces in E15, in general, are contained in canal hypersurfaces. Finally, we give an example.

The effect of near-field earthquake records on the strain input energy of structures is investigated in this paper. Near-field records differ from other types of record by special characteristics. Long-period pulses, which are added to background records, are examples of those special features that are studied in this paper. Although both pulses and background records are statistical objects, the pulses usually behave more deterministically than underlying records. Considering this point, it is reasonable to compute the response of a structure to such earthquakes in two steps (i.e. deterministic and probabilistic phases) and, then, superimpose the results. Handling responses to near-field records in this way leads to more accurate response evaluations, because of extracting the deterministic part of the results from the statistical procedure. For this purpose, the response of different structures to near-field records is evaluated and the results are proposed in the form of energy spectra. The findings show that, in near-fault zones, an increase in ground motion magnitude results in higher spectral peak strain energy and, also, a higher period of occurrence, respectively. It is found that, close to the fault, the response is primarily governed by the pulse characteristic rather than by the background record. This trend inverts gradually as the distance to the fault increases. In intermediate regions, the energy spectra experience two major peaks, which correspond to the site dominant period and the pulse period, correspondingly.