Recommendations on seismic actions on bridges

The paper describes the main features of a technical Recommendation first draft on Seismic Actions on Bridges, promoted by the Spanish Ministry of Public Works (MOPT). Although much more research is needed to clarify the seismic behaviour of the vast class of problems present in port structures the current state of the art allows at least a classificaton of subjects and the establishment of minimum requirements to guide the design. Also the use of more refined methods for specially dangerous situations needs some general guidelines that contribute to mantein the design under reasonable safety margins. The Recommendations of the Spanish MOPT are a first try in those directions

Numerical analysis of axisymmetric shells by one-dimensional continuum elements suitable for high frequency excitations

Axisymmetric shells are analyzed by means of one-dimensional continuum elements by using the analogy between the bending of shells and the bending of beams on elastic foundation. The mathematical model is formulated in the frequency domain. Because the solution of the governing equations of vibration of beams are exact, the spatial discretization only depends on geometrical or material considerations. For some kind of situations, for example, for high frequency excitations, this approach may be more convenient than other conventional ones such as the finite element method

Cálculo sísmico de puentes. Estudio comparativo

Se presenta un estudio comparativo del cálculo sísmico de cinco puentes diferentes, utilizando diversos procedimientos. El objetivo es establecer la validez de los métodos sencillos, habitualmente utilizados, en función del tipo estructural del puente. El desarrollo se centra en el estudio de la importancia de las cargas dinámicas producidas en un puente situado en una zona sísmica intermedia, respecto a las cargas elásticas exigidas por las Norma de Cálculo de Puentes de Carreteras, haciendo especial mención de las diferencias que aparecen cuando la estructura está realizada en hormigón pretensado

Modelado de láminas ortotrópicas axisimétricas para excitaciones con alto contenido en frecuencia

El propósito de este artículo es el análisis lineal de estructuras laminares sometidas a excitaciones dinámicas con alto contenido en frecuencia. El método numérico propuesto utiliza para el modelado elementos continuos monodimensionales. La respuesta exacta de este tipo de elementos es conocida, y por lo tanto el método es más conveniente para este tipo de problemas que otros métodos convencionales basados en discretización espacial, por ejemplo el método de los elementos finitos (MEF), que precisarían de una malla muy fina para recoger adecuadamente los fenómenos de interés. El estudio aquí descrito se limita a estructuras axisimétricas con formas cilíndricas o cónicas. Se presentan criterios para modelar dichas estructuras mediante vigas sobre apoyo elástico

Recommendations on seismic actions on port structures

The paper describes the main features of a Technical Recommendation first draft on Seismic Action on port structures promoted recently by the Spanish Ministry of Public Works (MOPT). Although much more research is needed to clarify the seismic behaviour of the vast class of problems present in port structures the current state of the art allows at least a classification of subjects and the establishment of minimum requirements to guide the design. Also the use of more refined methods for specially dangerous situations needs some general guidelines that contribute to mantein the design under reasonable safety margins. The Recommendations of the Spanish MOPT are a first try in those directions

Seafloor environments on Madrid and El Cid mud volcanoes (Moroccan continental margin of the Gulf of Cádiz)

Simposio sobre el Margen Ibérico Atlántico (9º. 2018. Coimbra, Portugal)More than 70 mud volcanoes (MVs) are identified along the continental margin of the Gulf of Cadiz,,although only a few have been thoroughly sampled and direct observed. This work is a contribution to the knowledge of the Gulf of Cadiz MVs Madrid and El Cid, located in the continental slope known as Western Moroccan Field over 1300 m water depth. On Madrid MV extensive crusts and mud breccia were observed. Nevertheless in El Cid MV, the rocky fragments are of smaller size and mud breccia has not been sampled/observed on the surface. In both MVs, coral reefs colonizing rocky fragments and covering seafloor of metric size have been observed.Departamento de Ciencias de la Tierrra, Universidad de Cádiz, EspañaCentro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaCentro oceanográfico de Cádiz, Instituto Español de Oceanografía, EspañaInstituto Geológico y Minero de España, EspañaEstrutura de Missão para a Extensão da Plataforma Continental, Portuga

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A comparison of the relations of adolescent's own and their peers' academic motivation within different peer relationships

The present study compares the relation of early adolescents’ academic self-concept, effort regulation and task value with their peer of three distinct relationships, which named as mutual friendships, frequent interactive pairs and social groups. Data was collected from a secondary school in Hong Kong with 135 form 1 students and 176 form 3 students. Moderating effect of adolescents’ own motivation on help-seeking and peer-learning in each type of peer relationship and developmental difference were also explored. Different correlation found in academic self-concept and effort regulation across forms proves the existence of three distinct types of peer relationship. Result shows that social group’s academic characteristic is most predictable for early adolescent’s own academic motivation. Result also suggests that motivation on help-seeking and peer-learning moderate the relation of adolescents’ academic effort regulation and task value mainly in dyadic relationships, such as mutual friendships and frequent interactive pairs.published_or_final_versionEducational PsychologyMasterMaster of Social Science

Modelado de láminas ototrópicas axisimétricas para excitaciones con alto contenido en frecuencia

El propósito de este artículo es el análisis lineal de estructuras laminares sometidas a excitaciones dinámicas con alto contenido en frecuencia. El método numérico propuesto utiliza para el modelado elementos continuos monodimensionales. La respuesta exacta de este tipo de elementos es conocida, y por lo tanto el método es más conveniente para este tipo de problemas que otros métodos convencionales basados en discretización espacial, por ejemplo el método de los elementos finitos (MEF), que precisarían de una malla muy fina para recoger adecuadamente los fenómenos de interés. El estudio aquí descrito se limita a estructuras axisimétricas con formas cilíndricas o cónicas. Se presentan criterios para modelar dichas estructuras mediante vigas sobre apoyo elástico.Peer Reviewe

Effect of Thermal Ageing on the Impact and Flexural Damage Behaviour of Carbon Fibre-Reinforced Epoxy Laminates

Most of the composite materials that are used in aerospace structures have been manufactured using a thermostable matrix, as epoxy resin. The region of stability of these polymers is defined by the glass transition temperature (Tg). However, operating temperatures close and above the Tg can cause a variation in the properties of the polymer and consequently, modify the mechanical properties of the composite material. Therefore, it is necessary to understand the failure mechanisms that occur in the material in order to ensure stability and durability. The effect of temperature and time of exposure on the impact and flexural mechanical responses of carbon/epoxy composites are studied in this work. For that purpose, ageing treatments at temperatures below and above the Tg have been considered and then, impact and flexural tests have been performed. It was observed that thermal ageing cause two different effects: at temperatures below the Tg, there is an increase of the maximum strength because of a post-curing effect; however, the mechanical properties decrease at higher temperatures of thermal ageing due to the thermo-oxidation of the epoxy resin and the loss of adhesion in the matrix/fibre interface