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Aquest estudi consisteix en la caracterització mecànica del formigó projectat reforçat amb fibres i formigó reforçat amb fibres buidat als motlles mitjançant assaigs de compressió, mòdul assecant dʻelasticitat en compressió, assaig Barcelona, ​​assaig a flexió en bigues i en panells quadrats. Compara els resultats, analitza la resistència residual dels dos formigons i mitjançant l'assaig inductiu determina un 37% de rebot de fibres metàl·liques. Segueix els lineaments de la normativa UNE-EN 14651, proposada a la normativa prEN 14488-3 mètode B i del Model Code for Concrete Structures es determina que el tipus de fibres metàl·liques i la dosificació emprada compleix els requeriments per ser considerat estructural i poder reemplaçar lús de malles electrosoldades. La proposta a la normativa prEN 14488-3 fa referència a assaigs de formigó projectat utilitzant panells quadrats, mentre que la normativa UNE-EN 14651 fa referència a formigó reforçat amb fibres utilitzant bigues de secció transversal 150 x 150 mm. Dins la caracterització mecànica emprada en aquest estudi després d'assajar els panells quadrats aquests elements són tallats en bigues de secció transversal 100 x 100 mm i són assajades seguint les configuracions de la normativa UNE-EN 14651 per comparar els resultats de panells – bigues de 100 x 100 mm i bigues de 150 x 150 mm – bigues de 100 x 100 mm., Este estudio consiste en la caracterización mecánica del hormigón proyectado reforzado con fibras y hormigón reforzado con fibras vaciado en los moldes mediante ensayos de compresión, módulo secante de elasticidad en compresión, ensayo Barcelona, ensayo a flexión en vigas y en paneles cuadrados. Compara sus resultados, analiza la resistencia residual de ambos hormigones y mediante el ensayo inductivo determina un 37% de rebote de fibras metálicas. Sigue los lineamientos de la normativa UNE-EN 14651, propuesta a la normativa prEN 14488- 3 método B y del Model Code for Concrete Structures se determina que el tipo de fibras metálicas y la dosificación empleada cumple con los requerimientos para ser considerado estructural y poder reemplazar el uso de mallas electrosoldadas. La propuesta a la normativa prEN 14488-3 hace referencia a ensayos de hormigón proyectado utilizando paneles cuadrados, mientras que la normativa UNE-EN 14651 se refiere a hormigón reforzado con fibras utilizando vigas de sección transversal 150 x 150 mm. Dentro de la caracterización mecánica empleada en este estudio después de ensayar los paneles cuadrados estos elementos son cortados en vigas de sección transversal 100 x 100 mm y son ensayadas siguiendo las configuraciones de la normativa UNE-EN 14651 para comparar los resultados de paneles – vigas de 100 x 100 mm y vigas de 150 x 150 mm – vigas de 100 x 100 mm., This study consists of the mechanical characterization of the fiber-reinforced shotcrete and fiber-reinforced cast concrete in the molds by compression tests, secant modulus of elasticity in compression, Barcelona test, flexural test on beams and square panels. It compares the results, analyzes the residual resistance of both concretes and through the inductive test determines a 37% rebound of steel fibers. It follows the guidelines of the UNE-EN 14651 standard, proposed to the prEN 14488-3 method B standard and the Model Code for Concrete Structures, it is determined that the type of steel fibers and the dosage used meet the requirements to be considered structural and power replace the use of electro-welded mesh. The proposal to the prEN 14488-3 standard refers to shotcrete tests using square panels, while the UNE-EN 14651 standard refers to fiber-reinforced concrete using beams with a cross section of 150 x 150 mm. Within the mechanical characterization used in this study, after testing the square panels, these elements are cut into beams with a cross section of 100 x 100 mm and are tested following the configurations of the UNE-EN 14651 standard to compare the results of panels - steel beams. 100 x 100 mm and 150 x 150 mm beams – 100 x 100 mm beams.

The use of fibre reinforced concrete (FRC) elements without traditional reinforcement is increasing in applications for which the structure is exposed to cyclic loadings, such as pavements, bridge deck overlays and offshore structures. Cyclic loads produce tensile stresses that can lead to crack initiation and propagation, and thus compromising the mechanical performance and durability that may bring about noncompliance with service or limit state requirements. The loss of performance owe to material fatigue-induced strength degradation might be significantly accelerated in cracked cross-sections. This contribution presents the results and outcomes derived from an experimental program on the flexural fatigue behaviour of pre-cracked fibre reinforced concrete carried out on notched 600x150x150 mm beams. The evolution of the crack opening displacement and other design-sensitive parameters were monitored and analysed. The understanding of the damage propagation is the basis for the proposal of a design-oriented constitutive model, which is meant to be used for predicting the fatigue life in cracking-allowed concrete structures designed to be subjected to fatigue-inducing loads. The constitutive model was calibrated for a content (9 kg/m3) of a specific type of macrosynthetic fibre and considering different fatigue load levels., Postprint (author's final draft)

The present paper deals with an experimental study on the flexural fatigue behaviour of pre-cracked polypropylene fibre reinforced concrete with two different volume of fibre. Mechanical response was evaluated through compressive strength, elastic modulus and static bending test. Fatigue test considered an initial crack width accepted in the service limit state and the evolution of the crack opening displacement of the beams subjected to a prescribed number of cycles (1,000,000 or 2,000,000). After the cyclic load, the post-fatigue residual strength was evaluated and compared to the static response. Results suggest that the mechanism of crack development is independent of the adopted fibre content. The post-fatigue strength seems to be unaffected by accumulated damage due to cyclic load and the static load-crack opening displacement curve might be used as a criterion to predict the residual strength. Furthermore, a conceptual model is proposed to predict the crack opening as a function of number of cycles in view of accumulated fatigue damage. The equation was validated for different fibre content and polypropylene fibres., The first author thanks the Brazilian National Council for Scientific and Technological Development for the scholarship granted (233980/2014-8). This research was enabled by funds provided by the SAES project (BIA2016-78742-C2-1-R) of Spanish Ministerio de Economía, Industria y Competitividad., Peer Reviewed, Postprint (published version)

This paper presents an experimental investigation on the post-crack flexural fatigue behaviour of a steel macrofiber reinforced concrete (SFRC) and a high performance steel microfiber reinforced concrete (HPFRC), on notched beams considering the crack opening for serviceability condition. Different load levels were applied by means of three-point bending tests in order to verify the fatigue life. Performance of SFRC and HPFRC was compared under cyclic dynamic tests. Higher load levels seem to lead to failure through a continuous pull-out of the fibres, generating a more ductile response. Smaller load levels can be responsible for the progressive weakening of the fibre-matrix interface through micro-cracks. The conducted probabilistic approach has demonstrated to be suitable to predict the flexural fatigue life of pre-cracked SFRC and HPFRC for a desired probability of failure. From the experimental intrinsic scatter of the fatigue phenomenon, in particular for high levels of applied fatigue load, the amount of fibres in the cracked cross section seems to play an important role in withstanding the fatigue load., The first author would like to thank the Brazilian National Council for Scientific and Technological Development for the scholarship granted (233980/2014-8). This research has been possible owe to the economic funds provided by the SAES project (BIA2016-78742-C2-1-R) of Spanish Ministerio de Economía, Industria y Competitividad., Peer Reviewed, Postprint (published version)

The objective of this paper is to analyse the mechanical behaviour of polypropylene fibre reinforced concrete subjected to load cycles and propose a model to predict the crack-opening increase and mechanical performance evolution over the cycles. Fatigue tests were performed in pre-cracked specimens with two fibre types and contents to assess the evolution of the crack-opening for prescribed numbers of load cycles. The residual flexural tensile strength was assessed before and after these tests to estimate the impact of the cycles in the remaining resistant capacity of the specimens. Results suggest that the mechanism of crack propagation is independent of the fibre type and content. The accumulated damage due to the cycles produces an offset in the quasi-static residual tensile strength curve. These findings underpin the proposal of a model to predict the evolution of the crack-opening and the remaining resistant capacity. An optimisation procedure is proposed to derive the model parameters using a limited number of initial load cycles., The first author thanks the Brazilian National Council for Scientific and Technological Development for the scholarship granted (233980/2014-8). This research was enabled by funds provided by the SAES project (BIA2016-78742-C2-1-R) of Spanish Ministerio de Economía, Industria y Competitividad. Likewise, this work was only possible thanks to the support from the Laboratory of Technology of Structures and Materials “Lluis Agulló" of Polytechnic University of Catalonia., Peer Reviewed, Postprint (author's final draft)

In order to evaluate the fatigue behaviour of Ultra-High Performance steel Fibre Reinforced Concrete (UHPFRC) in bending an experimental campaign with prismatic specimen of 75 x 75 x 275 mm was carried out. Fatigue tests were performed considering four different values for the upper limit of the applied load (S): 65%, 70%, 75% and 80% of the maximum strength obtained through the bending test. The results of the fatigue tests were analysed as a function of the crack mouth opening displacement (CMOD) and total number of cycles (N), as well as with Wöhler curves (S-N curves). In addition, the results considered the crack opening range and the toughness of the material. It was observed that when subjected to cyclic loadings of 65% and 70%, the residual strength of the specimens appears to be unaffected even after they are cracked. Through analytical relations, it can be verified that the cracked specimens of UHPFRC behave as a rigid solid. The obtained results suggest that the fatigue strength limit of UHPFRC is about 67% of the maximum flexural strength, which is in agreement with the literature., Postprint (published version)