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In practice, foundations are settled on the soft layers of soil, so the ground must be designed as well as the structure. Wave propagation and hysteresis damping of soil layers may alter the seismic response of flexible-base design in comparison to controversial fixed-base. Lots of uncertainties about this issue, necessitate most of seismic design standards including Iranian standard No. 2800 to neglect the soil – structure interaction (SSI) effects on seismic response of structures. A simplified finite elements method is proposed in this research and applied according to the Standard No. 2800 criteria on reinforced concrete structures. The accuracy and efficiency of this method is compared with four other similar researches, and the results of time history and modal analyses for descriptive reinforced concrete systems are ilusterated in the form of figurs and charts

Dynamic Soil-Structure Interaction (S-SI) behavior on the seafloor describes the coupling of a structure and the seabed and their combined response to the influence of waves and currents and the material properties of the seafloor. S-SI problems are significant to the Navy when structures placed on the seafloor must be recovered promptly, maintain position (such as no lateral movement), maintain stability (such as not bury or tilt), and not be affected by abrasion and/or sedimentation. This report develops the critical marine geotechnical, geological, and environmental problems of S-SI for structure(s) placed on fine-grained sediments common to coastal areas. Only limited S-SI analysis of sand is presented in this report; however, significant additional work is seriously needed to support various naval operational scenarios requiring reliable predictive models. Detailed future research recommendations are provided herein and the ultimate success of the predictive models and operational strategies will depend critically upon the close integration of research by environmental scientists, geologists, and geotechnical engineers. Keywords: Soil structure interaction; Seafloor sediments; Soil behavior; Geotechniques; Soil properties; Skidding; Lateral motion; Environmental data; Mass movement; Wave-sea bottom interaction; Subseafloor properties; Bearing capacity; Geotechnical engineering.

Dynamic Soil-Structure Interaction (S-SI) behavior on the seafloor describes the coupling of a structure and the seabed and their combined response to the influence of waves and currents and the material properties of the seafloor. S-SI problems are significant to the Navy when structures placed on the seafloor must be recovered promptly, maintain position (such as no lateral movement), maintain stability (such as not bury or tilt), and not be affected by abrasion and/or sedimentation. This report develops the critical marine geotechnical, geological, and environmental problems of S-SI for structure(s) placed on fine-grained sediments common to coastal areas. Only limited S-SI analysis of sand is presented in this report; however, significant additional work is seriously needed to support various naval operational scenarios requiring reliable predictive models. Detailed future research recommendations are provided herein and the ultimate success of the predictive models and operational strategies will depend critically upon the close integration of research by environmental scientists, geologists, and geotechnical engineers. Keywords: Soil structure interaction; Seafloor sediments; Soil behavior; Geotechniques; Soil properties; Skidding; Lateral motion; Environmental data; Mass movement; Wave-sea bottom interaction; Subseafloor properties; Bearing capacity; Geotechnical engineering.

Accurate model tests of problems in soil mechanics may be carried out by the technique of centrifugal modelling, which preserves the correct magnitude and distribution of stress in the soil. There is a consistent set of rules to relate the behaviour of a full-size prototype to the behaviour of a model, not only for static tests, but also for dynamic events. The object of this investigation was, firstly, to show that dynamic modelling was possible, and secondly, to use the technique for some initial studies of soil-structure dynamic interaction and earthquake motion. The project used the geotechnical centrifuge at Cambridge University, England, and this will accept packages of almost one tonne in mass at a maximum acceleration of 155 g.

Soil-Structure interaction under blast loading was investigated both experimentally in 10 g-ton centrifuge and analytically by finite element simulation. In the centrifuge experiments, circular pipes made of micro-concrete were buried in a dry sand and tested in the centrifuge to simulate the effects of gravity-induced overburden stresses which played a major role in controlling the soil stiffness and, subsequently, the response of the pipe. The blast loading was simulated by a pressure pulse generated by rupturing a burst disc in an impact generator. Surface stress gages and contact stress gages both made of polyvinylidene fluoride were built and calibrated to measure air blast magnitudes and contact pressures. The centrifuge experiments provided insight into the dynamic response of buried pipes and a data base for the verification of numerical results. These results were obtained by linear and non-linear finite element analyses of the experiments duplicating the surface overpressure loading. The suitability of constitutive relations for both soil and micro-concrete were verified by comparing test results and analysis. The effects of soil arching around the buried pipe was also delineated from both experiment and analysis.

This report describes a doubly asymptotic (DA), boundary-element (BE) treatment of a surrounding soil medium that offers considerable promise for dynamic soil-structure interaction analysis. The soil-structure interaction is reduced to a surface relationship that is asymptotically exact at both high and low frequencies. Governing equations for linear problems are developed in matrix form for application to complex structures. Numerical results are presented for a two-dimensional problem for which analytical solutions have appeared in the literature. Good agreement between the DA/BE and analytical results is observed. (Author)

THe dynamic response of flexible surface strip-foundations allowed to uplift is numerically obtained for externally applied forces of a transient time variation. The soil medium is represented by an isotropic, homogeneous and linear half-space. The soil is treated by a time domain boundary element method, while the flexible foundation is treated by the finite element method. It was concluded that intermediate relative stiffness leads to moderate deformations when uplift is permitted. Very flexible footings produce higher deformations in unilateral contact compared to bilateral contact, and thus should be considered in their design. Unilateral contact does not significantly increase deformations for stiff footings subjected to concentrated central loading. However, relatively large deformation differences occur when the loading is eccentric, necessitating consideration of uplift in their design.

1Other Things Being Equal

By Emma Wolf

Ruth Levice, the daughter of a rich San Francisco Jewish merchant, meats Dr. Herbert Kemp, and they slowly fall in love. However, she is Jewish and he is not. Can love overcome such an obstacle? And what is more important, duty or love? (Summary by Stav Nisser)

2Apis Mellifica

By C. W. Wolf

Wolf's essay considers the homeopathic medicine Apis Mellifica, or the poison of the honey bee, as a therapeutic agent based on his experience as a practicing physician. (Summary by Marie Daum)

Johann Wilhelm Wolf war Germanist und Schriftsteller, sein Schwager Wilhelm von Ploennies war Leutnant, Militärschriftsteller und Übersetzer. Gemeinsam ließen sie sich auf Streifzügen durch den Odenwald von den Menschen, die sie trafen und von den Soldaten der Kompanie des Ludwig Ploennies Sagen, Märchen und Mythen erzählen, die sie aufschrieben und veröffentlichten. (Summary by seito)