1,721,005 research outputs found
The role of concrete substrate roughness on externally bonded Fabric-Reinforced Cementitious Matrix (FRCM) layers
Full text linkFabric-Reinforced Cementitious Matrix composites represent a promising solution for the strengthening and the upgrading of existing concrete structures. The bond-slip behavior of the FRCM-substrate interface plays an important role in the effectiveness of the reinforcement application. This paper is devoted to understanding the effect of the substrate roughness – obtained in this case by means of a hydroscarification of concrete surfaces with different water pressure stages – on the bond behavior at the interface level, by performing single lap shear tests with a very limited anchorage length. A proper surface machining can increase the roughness of the substrate, ensuring a better interaction at the interface layer, thus preventing premature delamination failures
The Aemodogryllinae cave crickets from Guizhou, Southern China (Orthoptera, Rhaphidophoridae).
No full textMemorie del Museo Civico di Storia Naturale di Verona – 2. Serie, Monografie Naturalistiche 3 -
ISSN 1724-7357
Mechanical behaviour of TRC composites: Experimental and analytical approaches
Full text linkTextile reinforced concrete (TRC) is a promising high-performance material that has been employed with success in new constructions, as well as a strengthening layer of existing structural components. In this work, we document the optimisation procedure of textile-based composites for new construction and for the seismic retrofitting of under-reinforced concrete elements and masonry buildings. The study, aimed at maximising the material performances avoiding waste of economic resources, was addressed by means of a series of uniaxial tensile tests conducted on a wide set of alkali-resistant (AR) glass fabrics and TRCs. The samples differed in terms of cement-based matrices, embedded textiles and addition of dispersed microfibers. The results highlight the effects of fabric characteristics and introduction of short fibres on the mechanical behaviour, proposing novel comparison parameters based upon the load bearing capacity and the deformation response of the composites. The application of simplified analytical models borrowed from the literature finally revealed the limitations of the available predictive approaches, suggesting future lines of investigation
Stiffness Degradation of Textile-Reinforced Mortar under Unloading-Reloading Tensile Cycles
No full textTextile-reinforced mortar (TRM) has proved to be a valid engineering material for the upgrading and retrofitting of existing masonry and concrete structures subject to seismic actions, because it can be applied in thin layers that can increase load-bearing capacity while providing significant durability. However, characterization activities at the composite scale have mainly focused on the material's monotonic behavior and few studies have so far addressed the material's performance in the presence of cyclic actions. In this work, we set ourselves the goal of investigating the uniaxial tensile behavior of a series of cement-based matrix composites reinforced with alkali-resistant (AR) glass fabrics, also considering the possible inclusion of short dispersed polyvinyl alcohol (PVA) fibers. Quantification of the stiffness degradation accumulated by the composites during unloading-reloading cycles allowed us to evaluate the damage evolution in uniaxial tension through data interpolation, providing analytical formulations that may represent a benchmark for the validation of advanced nonlinear simulations
Dolichopoda muceddai Rampini & Di Russo, nuova specie di una famiglia di Ortotteri nuova per la Sardegna (Orthoptera Rhaphidophoridae)
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A Unidirectional Ribbed Slab System with Prefabricated Textile-Reinforced Concrete Shells
No full textThe use of innovative high-performance cementitious materials enables the development of advanced structural systems characterized by enhanced lightness, durability, sustainability, and mechanical performance. In this paper, we propose a partially precast unidirectional ribbed floor system consisting of very high-performance fiber-reinforced concrete (VHPFRC) I-beams, textile reinforced concrete (TRC) stay-in-place formworks, and ordinary fiber-reinforced concrete (FRC) finishes. A description of the conceptual design underlying the proposed building system is followed by a depiction of the materials and construction procedures used. Special emphasis is placed on the mechanical behavior of the TRC, both at the material and structural scales. Within this context, the membrane and flexural responses of thin beam specimens are discussed and followed by the experimental analysis of the movable prefabricated shells inspired by Pier Luigi Nervi’s ferrocement constructions, subject to transient actions associated with typical construction stages
Pull-Out Tests on AR-Glass Fabrics Embedded in Plain and Fibre-Reinforced Cementitious Mortars
No full textAs reflected in recent literature, the use of fabric-reinforced concrete (TRC) composites is growing both for the fabrication of new lightweight components (e.g., sandwich roof panels) and the strengthening/retrofitting of underperforming masonry or reinforced concrete structures. Given the wide variability of commercially available matrices and fabrics, a general requirement for the structural application of these materials is the experimental characterization of the composite mechanical properties. Such investigation, which generally includes characterization of the base materials (concrete/mortar and fabrics) and uniaxial tensile tests on composite coupons, should also include identification of the bond-slip properties at the fabric-to-matrix interface, if a proper design of the TRC application is to be achieved. In addition, the bond behavior is a key parameter to effectively simulate the composite response in nonlinear finite element numerical simulations. In this paper, a novel and rather simple test setup is proposed to determine the pull-out properties of glass fabric strips embedded into a cement-based matrix. The experimental campaign included a first series of twelve TRC specimens, in which both the total anchorage length and the fabric orientation (warp and weft) were varied. Subsequently, a second set of TRC coupons was tested, to investigate the effect of the addition of short polyvinyl alcohol (PVA) fibres to the mortar
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