On the influence of uplift pressure in concrete gravity dams

Cracks are often present in concrete dams, and may have relevant dimensions. The evaluation of the safety factor of old dams under higher flood levels has been investigated through fracture mechanics in previous years. Crack stability in concrete dams can correctly be predicted when uplift pressures are accurately modelled. Current models consider a uniform uplift pressure distribution, but recent experimental results show that it varies along the crack faces. In the present paper, uplift pressure effects in cracked concrete gravity dams are studied. A parametric study on the influence of uplift pressure on stress intensity factors and crack-propagation angle is performed. Furthermore, uplift pressure effects on the LEFM scale law for the maximum water level carried by cracked gravity dams are examined

Experimental study on the behavior of SFRC columns under seismic loads

Research studies on Steel Fiber Reinforced Concrete (SFRC) elements have been mostly concentrated on the performance under static loading. Few information are available in literature on the behavior, analysis and design under seismic loading. The research work herein presented concerns an experimental investigation on SFRC columns tested under cyclic horizontal loading and constant axial load. Aim of the study is the evaluation of the fibers’ effects on the overall behavior of the columns. The spacing and the diameter of the stirrups were varied in order to verify their influence. Test results indicate that fibers can significantly reduce the level of damage, typically expected in the plastic hinge zone, by preventing the concrete cover to spall out at earlier stages; it follows that the use of fiber, in combination with traditional rebars, seems an optimal solution with special reference for the Damage Limit State. Moreover, fibers increase the ductility and the energy dissipation of the columns

Studio sperimentale sul comportamento dell'impalcato ligneo per il miglioramento sismico del Palazzo della Loggia

Atti del Convegno di studi "Storia e problemi statici del palazzo della Loggia di Brescia" - Università degli Studi di Brescia - Facoltà di Ingengeria - ottobre 200

Steel fibers reinforced concrete for precast tunnel segments

The paper concerns precast tunnel segments for the Line 1 of the Valencia Metro (Venezuela) where the conventional reinforcement (rebars) may be partially substituted by steel fibers. After the experimental determination of the material properties, nonlinear analyses allowed to study the structural behavior of the tunnel segments with different types of reinforcement, according to different loading conditions. Also an optimized reinforcement, based on a combination of rebars and steel fibers, is adopted

Fatigue behavior of SFRC under Bending

The aim of the present work was to investigate the post-peak cyclic behavior of Steel Fiber Reinforced Concrete (SFRC) under bending by means of an experimental campaign. The effects of two different volume fraction of fibers (0.5% and 1.0%) and three different load levels have been considered and the fatigue performances of plain and SFRCs are compared. Static monotonic tests were performed as reference. The results from fatigue tests have been compared in terms of cyclic creep curves and S-N diagrams. Special attention was devoted to the crack opening rate, the material toughness, the energy dissipation and the stiffness degradation. It highlighted that fibers can improve the fatigue life of SFRC for high load levels (low-cycle fatigue), whereas with the high-cycle fatigue fibers don’t seem to be effective. In both cases, however, fibers seem to improve the energy dissipation. Moreover, even though the increase of fiber content improves the fracture properties, it does not seem particularly effective on the fatigue properties

Steel Fibers as Shear Reinforcement for Beams

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