Experimental Study of the Dynamic Interaction Between the Foundation of the NEES/UCSD Shake Table and the Surrounding Soil

The results of an extensive experimental study of the dynamic interaction between the foundation block for the NEES/UCSD Large High Performance Outdoor Shake Table and the surrounding soil are presented. The vibrations induced by the two large NEES/UCLA eccentric mass shakers were recorded at multiple stations within the reinforced concrete foundation block and on the soil up to distances of 270 m from the block. The results obtained for the deformation pattern of the reaction block, the frequency response at selected stations on the block, and the average rigid-body motion of the foundation and its dependence on frequency for longitudinal (EW) excitation are presented in detail. Comparison of the response during shaker-induced vibrations with that resulting from the much stronger actuator forces shows that linearity holds for the range of forces involved. The attenuation of the ground motion away from the reaction block is also described

The direct boundary element method: 2D site effects assessment on laterally varying layered media (methodology)

The Direct Boundary Element Method (DBEM) is presented to solve the elastodynamic field equations in 2D, and a complete comprehensive implementation is given. The DBEM is a useful approach to obtain reliable numerical estimates of site effects on seismic ground motion due to irregular geological configurations, both of layering and topography. The method is based on the discretization of the classical Somigliana's elastodynamic representation equation which stems from the reciprocity theorem. This equation is given in terms of the Green's function which is the full-space harmonic steady-state fundamental solution. The formulation permits the treatment of viscoelastic media, therefore site models with intrinsic attenuation can be examined. By means of this approach, the calculation of 2D scattering of seismic waves, due to the incidence of P and SV waves on irregular topographical profiles is performed. Sites such as, canyons, mountains and valleys in irregular multilayered media are computed to test the technique. The obtained transfer functions show excellent agreement with already published results

Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes.

8 páginas, 4 tablas, 8 figuras.The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three saltmarsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and managementFinancial support from the Spanish Ministry of the Environment (MMA, project 05/99) and the Junta de Andalucía (research group 4086)enabled us to carry out the present work.Peer reviewe

Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes.

8 páginas, 4 tablas, 8 figuras.The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three saltmarsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and managementFinancial support from the Spanish Ministry of the Environment (MMA, project 05/99) and the Junta de Andalucía (research group 4086)enabled us to carry out the present work.Peer reviewe

Doñana. Acta vertebrata. vol 24(1/2)

Alimentación de la lagartija colilarga Psammodromus algirus (L) (Sauria, Lacertidae), en el litoral de Huelva (SO EspañaLa alimentación de Myotis myotis Borkh, 1791 (Chiroptera, Vespertilionidae) en la cuenca del rio Guadix (sureste de España)Distribución y selección de hábitat de la garduña (Martes foina, Erxleben, 1777) en Vizcaya y Sierra Salvada (Burgos).Nuevo modelo de trampa para reducir el impacto de la pesca de cangrejos sobre los vertebrados en las marismas del GuadalquiviThe functions of song and the spatial pattern of song production in the rufous bush chat (Cercotrichas galactotes)Migración e invernada de las lavanderas cascadena Motacilla cinerea y blanca M. alba en la Penínula Ibérica e Islas BalearesAbundancia y reproducción de Glis glis (Linnaeus, 1766) (Rodentia, Gliridae) en el Pirineo occidental.Estatus de residencia, categorización trófica y abundancia de aves en el zoológico de La Plata, ArgentinaAvifauna reproductora y estructura del hábitat en la campiña y sierras Subbéticas de JaénDispersión de semillas de retama (Retama sphaerocarpa (L.) Boiss por el conejo (Oryctolagus cuniculus L.) en el centro de EspañaGuía para la identificación de restos óseos pertenecientes a algunos peces comunes en las aguas continentales de la Península Ibérica para el estudio de la dieta de depredadores ictiófagosDistribución y abundancia del corzo (Capreolus capreolus L. 1758) en la provincia de JaénAlimentación de las larvas de anuros en ambientes temporales del sistema del rio Paraná, Argentina.Mauremys leprosa como presa de Lutra lutraNota sobre la alimentación del lince ibérico en el Parque Natural de la Sierra de Andújar (Sierra Morena oriental)Presencia de Echinococcus granulosus (Cestoda) en un lobo ibérico (Canis lupusLa orientación de los nidos de paseriformes estepariosComparación de la dieta obtenida a partir de muestras estomacales y fecales del Tuco-tuco, Ctenomys mendocinus, en dos poblaciones de la precordillera de los Andes, ArgentinaEstructura genética y distribución de la variabilidad enzimática en poblaciones naturales de estornino negro (Sturnus unicolor)Estimación de la disponibilidad trófica para el quebrantahuesos (Gypaetus barbatus) en Cataluña (NE España) e implicaciones sobre su conservaciónPeer reviewe

Comprehensive mechanics-based virtual model of NHERI@UCSD shake table-Uniaxial configuration and bare table condition

A mechanics-based virtual model of the NHERI@UCSD large high-performance outdoor shake table (LHPOST) in its uniaxial configuration and under bare table condition is presented. The virtual model includes: (i) a reprogrammed version (i.e., virtual replica) of the actual controller, (ii) a servovalve model including servovalve spool dynamics and two independent servovalve flow nonlinearities for each of the four servovalves of the system, (iii) an actuator model for each of the two single-ended actuators, (iv) two accumulators modeling the average supply pressure drop at the entrance of the servovalves, and (v) a one-degree-of-freedom mechanical subsystem model. Based on forced vibration test results for the foundation block, it was found that the soil-foundation compliance effects do not need to be included in the virtual model of the LHPOST. The virtual model presented is able to predict accurately the actual shake table platen response under narrow and broadband inputs with the controller gains set to the same values as on the actual shake table. Moreover, the fourth stage spool displacements and actuator driving force from actual tests are reproduced accurately by the virtual model. The mechanics-based virtual model presented in this article can be coupled with FE models of specimens to be tested on the LHPOST and can be used to improve the signal reproduction fidelity of the LHPOST and to develop more advanced model-based shake table controllers