Ductilityof fiber-reinforcedself-consolidatingconcreteundermulti-axial compression

The results of 12 multi-axial compression tests performed on cylinders made of self-consolidating concrete, plain (SCC) and reinforced with steel fibers (FR-SCC), are presented. In the experimental campaign, four ‘‘reference'' confining pressures (0, 1, 3 and 10 MPa) were applied on the lateral surface of the specimens. After the first stage of loading, when a hydraulic stress was applied to the cylinders, and progressively increased up to the value of a pre-established confining pressure, a longitudinal compressive load was used to generate crushing of concrete. During this failure, the post-peak behavior of SCC and FR-SCC can be defined by a non-dimensional function that relates the inelastic displacement and the relative stress during softening. Such a function also reveals the ductility of SCC, which increases with the confinement stress and with the fiber volume fraction. In particular, by adding 0.9% in volume of steel fibers, FR-SCC can show practically the same ductility measured in unreinforced SCC with 1MPa of confining pressure. Thus, the presence of an adequate amount of fibers in SCC columns is sufficient to create a sort of distributed confinement

Sismabeton: a new frontier for ductile concrete

The high ductility of Fiber Reinforced Self-consolidating concrete (called Sismabeton) can be developed not only in tension but also in compression. This aspect is evidenced in the present paper by measuring the mechanical response of normal concrete (NC), plain self-compacting concrete (SC) and Sismabeton cylindrical specimens under uniaxial and triaxial compression. The post-peak behaviour of these specimens is defined by a non-dimensional function that relates the inelastic displacement and the relative stress during softening. Both for NC and SC, the increase of the fracture toughness with the confinement stress is observed. Conversely, Sismabeton shows, even in absence of confinement, practically the same ductility measured in normal and self-compacting concretes with a confining pressure. Thus, the presence of Sismabeton in compressed columns is itself sufficient to create a sort of active distributed confinement

Growth rates and age at adult size of loggerhead sea turtles (<em>Caretta caretta</em>) in the Mediterranean Sea, estimated through capture-mark-recapture records

A partir de registros de capturamarcaje- recaptura, se estimaron por primera vez en el Mediterráneo las tasas de crecimiento de las fases juveniles de la tortuga boba (Caretta caretta). Se liberaron treinta y ocho tortugas a partir de la costa italiana y se reencontraron después de 1.0-10.9 años en el periodo 1986-2007. El promedio de LCC (longitud curvada del caparazón) varió de 32.5 a 82.0 cm y se observaron tasas de crecimiento variables, de 0 a 5.97 cm/año (promedio: 2.5). La asociación entre la tasa de crecimiento anual y tres covariables (año promedio, talla promedio e intervalo de tiempo) se investigó a través de un modelo no-paramétrico. Solamente la talla media mostró un claro efecto en la tasa de crecimiento, descrito por una curva monotónica descendente. La variabilidad observada indica que factores no incluidos en el modelo, probablemente relacionados con el individuo, tienen un importante efecto en las tasas de crecimiento. En base a la función de crecimiento monotónicamente decreciente que indica que no hay esfuerzo en el crecimiento, se uso una función de crecimiento de von Bertalanffy para estimar el tiempo requerido por las tortugas para crecer dentro del rango de tallas observado. Los resultados indican que las tortugas necesitarán de 16-28 años para alcanzar 66.5-84.7 cm LCC, la talla promedio de anidación observada en las más importantes áreas de anidación del Mediterráneo, lo que puede ser considerado como una aproximación a la talla de madurez

Sismabeton: a new frontier for ductile concrete

The high ductility of Fiber Reinforced Self-consolidating concrete (called Sismabeton) can be developed not only in tension but also in compression. This aspect is evidenced in the present paper by measuring the mechanical response of normal concrete (NC), plain self-compacting concrete (SC) and Sismabeton cylindrical specimens under uniaxial and triaxial compression. The post-peak behaviour of these specimens is defined by a non-dimensional function that relates the inelastic displacement and the relative stress during softening. Both for NC and SC, the increase of the fracture toughness with the confinement stress is observed. Conversely, Sismabeton shows, even in absence of confinement, practically the same ductility measured in normal and self-compacting concretes with a confining pressure. Thus, the presence of Sismabeton in compressed columns is itself sufficient to create a sort of active distributed confinement

Applicazioni della teoria delle linee d'influenza in strutture viscoelastiche

Atti dell'Istituto di Scienza delle Costruzioni del Politecnico di Torin

Analisi approssimata dello stato di tensione in sezioni precompresse composte da più frazioni viscoelastiche

Atti dell'Istituto di Scienza delle Costruzioni del Politecnico di Torin

Considerazioni sulle deformazioni differite di corpi viscoelastici in coazione

Atti dell'Istituto di Scienza delle Costruzioni del Politecnico di Torin