1,721,114 research outputs found
Plain and Fiber Reinforced Concrete Beams under Shear Loading: Structural Behavior and Design Aspects
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Shear strength of FRC members with little or no shear reinforcement: a new analytical model
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Un nuovo modello analitico per il progetto a taglio di elementi in calcestruzzo fibrorinforzato privi di armatura trasversale
No full textHigh strength full-scale beams under flexure and shear: an experimental study
No full textPrefabrication is generally intended as a way to optimize production, handling and placing of structural elements with time and cost savings. Moreover, any plant production guarantees a rather improved quality control in terms of material and structural details with respect to in-situ construction. While combining also pre or post-tensioning techniques, it is possible to produce structural elements having quite high bearing capacity, such as bridge girders, long spanning principal or secondary beams and roof elements. The recent technological advancements in the production of High Strength Concrete (HSC), partially recognized by many international Standards, have focused the interest on the structural behavior of members made of high strength or high performance concrete. Five tests of full-scale precast elements, carried out at the University of Brescia, will be presented in this paper. One flexure test and four shear tests were performed on inverse T beams. The efficiency of HSC, the collapse modes, the post-cracking stiffness, the crack pattern and its evolution were monitored and will be herein discussed. Lastly, some comments related to shear and flexure requirements included in the recent new Italian Standard will be supplied
Fiber reinforced concrete characterization through round panel test - Part II: analytical and numerical study
No full textA new round panel test for the characterization of fiber reinforced concrete: a broad experimental study
No full textStandard test methods for determining the mechanical properties of Fiber Reinforced Concrete (FRC) are properly defined if they reproduce the actual structural behavior. Among many proposals, a round panel test seems to have all potentials to become an easy-to-use tool and, at the same time, a reliable procedure for the characterization of FRC, in terms of toughness and the post-cracking constitutive cohesive law. A new geometry for the round panel test is herein proposed and discussed in order to make the panel easier to place, handle, and test, therefore avoiding one of the major drawbacks that limit an extensive utilization of the panel test.A comparison between different test typologies for characterizing FRC is reported and discussed in the present paper, with special emphasis on the different scatter that each test produces. Tests are performed on beams as well as on panels. All specimens herein compared have the same concrete mechanical properties and fiber content. The aim of the experimental investigation is to critically discuss the advantages and disadvantages of each testing procedure, focusing on the applicability of the method and on the reliability of results toward a consistent characterization of the structural behavior. Suitable correlations among the different fracture and energy parameters defined in the standards considered are finally reported, and the results are very useful for harmonizing the available standards
Compression field modelling of fibre reinforced concrete shear critical deep beams: a numerical study
No full textNumerical analyses represent an important way to study the behaviour of both reinforced concrete and fibre reinforced concrete (FRC) structural elements under different loading conditions. Even though advanced computer codes able to model concrete fracture phenomena were developed in the past decades, numerical and analytical tools still require improvements and verifications against new experimental evidences, especially with respects to non-standard or quite critical structures. The present paper focuses on the numerical modelling of the shear behaviour of deep beams whether with fibres (FRC) or no shear reinforcement (PC), by means of a suitable implementation of the modified compression field theory (MCFT) and the disturbed stress field model (DSFM). After a numerical validation against some new available experimental results, specific numerical analyses were performed in order to study the size effect influence on the shear behaviour of FRC elements. These analyses were conducted considering a broad variety of beams, from 250 to 1500 mm high and with different amount of fibres. In the modelling, particular attention was devoted to the nonlinear behaviour of materials, especially with regard to the tension softening of FRC. The latter was modelled through inverse analysis on 3PBTs (EN14651) and by using the recently published Model Code 2010 linear model (MC2010). Refined nonlinear constitutive models and relationships for describing crack spacing and crack width, both in case of PC and FRC, were utilized as well. The numerical results show the reliability of the MCFT and DSFM in modelling both PC and FRC deep beams critical in shear. Moreover, the positive influence of fibres in reducing and significant altering the size effect trend is clearly confirmed by a broad parametric study herein reported
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