Evaluation of the fracture energy methods used in fiber reinforced concrete pavements by the maximum undamaged defect size concept (original) (raw)
Related papers
Fracture in high performance fibre reinforced concrete road pavement materials
2010
In this paper a simple, but effective methodology to simulate opening mode fracture in high performance fibre reinforced concrete is presented. To obtain the specific fracture energy of the material, load-deflection curves from three point bending (TPB) experiments are extrapolated. The proposed extrapolation technique is an adaptation of an approach originally developed for plain concrete. The experimental part of the paper includes a size effect study on TPB specimens. The post crack behaviour of the material is modelled using a cohesive softening function with crack tip singularity. Numerical simulation of the experiments is performed by means of an embedded discontinuity method. The simulation provides satisfactory predictions of the fracture behaviour of the material and the size-effect observed in the experiments. 1 Permanent address: CSIR Built Environment, Meiring Naudé Road, Pretoria, 0184, South Africa *Manuscript Click here to view linked References
Study of Fracture Mechanics on Fibre Reinforced Concrete
International Journal for Research in Applied Science and Engineering Technology IJRASET, 2020
Fracture mechanics gives a basic understanding of the characteristics of the structure afterload is being imposed on it. To avoid failure of the structure, analysis of fracture mechanics is very important. Fracture mechanics is the study of causes of cracks in a structure. A fracture means a crack of some length, the length of which increases upon loading. Fracture mechanics is about when that crack becomes critical and cannot sustain the load imposed upon it. When the crack gets to sufficient long length that the crack propagation goes from stable from unstable. For the structure to develop cracks, some energy is needed, that energy is called fracture energy. Examination of the energy for understanding the limit of tensile stress a structure can sustain is crucial. Usually for the development of crack three-point load method is used. A wide assortment has been proposed for this technique, to be executed.
IJRASET, 2021
This The influence of fibre reinforcement on crack propagation in concrete was studied. Thirty-five double torsion specimens, made with three types of fibres (fibre glass , straight steel fibres and deformed steel fibres) were tested. The variables were the fibre volume and size of the fibres. The test results indicated that the resistance to rapid crack growth increased somewhat with increasing fibre content up to about 1.25%-1.5% by volume. The degree of compaction had an enormous effect on the fracture properties .The fracture toughness increased with fibre content up to about 1.25% by volume, and then decreased , due to incomplete compaction. It was found that in this test geometry, fibres did not significantly restrain crack growth. It was also observed that once the crack had propagated down the full length of the specimen, the system changed from a continuous system to a discontinuous system, consisting of two separate plates held together by the fibre reinforcement. Different types of fibres did not significantly affect the fracture toughness.
EXPERIMENTAL INVESTIGATION ON THE FRACTURE BEHAVIOUR OF STEEL FIBER REINFORCED CONCRETE
Concrete is a composite material used for construction worldwide. The presence of cracks and pores inside concrete material is inevitable and it is necessary to investigate if they are stable or not. Hence problems related to fracture are vital in concrete. Fracture study assesses the ductile behavior of concrete structures under loading using various fracture parameters. Plain concrete possesses a very low tensile strength, limited ductility and little resistance to cracking. Addition of closely spaced and uniformly dispersed fibers to concrete acts as crack arrestor and substantially improves its static and dynamic properties. As a result of this ability to arrest cracks, fiber composites possess increased extensibility and tensile strength, both at first crack and at ultimate, particular under flexural loading; and the fibers are able to hold the matrix together even after extensive cracking. The present study aims at finding out how far the ductility of concrete can be improved by the addition of steel fibers in terms of fracture parameters by varying the fiber content. The fiber content was varied from 0% to 1.2% with an increment of 0.2%. The mechanical properties such as cube compressive strength, flexural strength, split tensile strength and modulus of elasticity were studied. From that results the optimum percentage of fiber was decided. Three-point bending test on notched beams (fracture tests) were conducted for determination of fracture parameters. The tests were done as per the guidelines of International Union of Laboratories and Experts in Construction Materials, Systems and Structures(RILEM)
Fracture Energy of Steel Fiber-Reinforced Concrete
Mechanics of Composite Materials and Structures, 2001
Steel fibre reinforced concrete (SFRC) is a cementitious material reinforced with a given content of discrete fibres. The use of SFRC in building construction has increased continuously due to its better mechanical properties, mainly, the energy absorption capacity.
Fracture in high performance fibre reinforced concrete pavement materials
2011
An innovative pavement system known as Ultra Thin Continuously Reinforced Concrete Pavement (UTCRCP) was recently developed in South Africa. The technology is currently being implemented on some major routes in the country. The system consists of a high performance fibre reinforced concrete pavement slab with a nominal thickness of approximately 50 mm. The material has a significant post crack stress capacity compared to
Modified Fracture Energy Method for Fibre Reinforced Concrete
2013
Fibre manufacturers specify different parameters for measuring the performance of their fibres, e.g. Re3 number or σ-ε diagram. However, these parameters depend largely on the strength class of the concrete; most specifically on the fracture energy, which is in itself a variable from cement manufacturer to manufacturer, even within the same class. It follows therefore that any fibre performance parameters as specified by the manufacturer's laboratory may vary significantly for the same concrete class in the user's laboratory. The ideal would be to find a performance parameter that is fibre specific and at least partially independent of the concrete, which could then be used for characterizing and comparing the various fibre types. In this paper I present a fibre added energy that could be used to characterize the fibres in this way.
Fracture Energy of Hybrid Fiber Reinforced Concrete
2007
In this paper, high strength concrete (HSC) of 53 MPa compressive strength was investigated. The constituents of the mix are dolomite as a coarse aggregate with 14 mm maximum aggregate size, siliceous sand as fine aggregate mixed together with a ratio of 1: 1.675, 443 Kg/m 3 ordinary Portland cement and 49 kg/m 3 silica fume as a cementitious material, and w/c was 0.29. The experimental program was designed to investigate the mechanical properties and fracture behavior of that HSC but having 0.8% fiber volume fraction of different types of short fiber, FRCs, (steel, glass, PP, steel+glass, steel+PP, glass+PP, and steel+glass+pp). The fracture behavior of edge-notched beam was determined in three-point bending condition. The beam length to depth ratio L/d was constant and equals to 4. The crack length to depth ratio, a/d, was equal to 0.2, 0.3, 0.4 and 0.5. The fracture parameters were determined using linear elastic fracture machine and Hillerborg model. The results in the present paper indicated that, adding short fibers to HSC improved its compressive strength in addition to the obvious enhancement in ductility except in the case of glass fiber, where, the compressive strength of GFRC is lower than that of HSC. The mode of failure for various FRC types under compression was varied compared to that of plain concrete. All these cubes failed due to multiple tensile vertical cracks with sudden explosive failure in the case of GFRC. In general, a small effect of short fibers in improving the indirect tensile strength and flexural strength of HSC. HSC with steel and PP hybrid fiber (SPPFRC) showed superior compressive, tensile, and flexural strengths and flexural toughness over the others FRCs.
FRACTURE ANALYSIS OF A HIGH-STRENGTH CONCRETE AND A HIGH-STRENGTH STEEL-FIBER-REINFORCED CONCRETE
Mechanics of Composites Materials, v. 43, n. 5, p. 479-486, 2007.
Keywords: R-curve, quasi-brit tle frac ture, frac ture tough ness, fi ber-re in forced con crete This pa per ad dresses the use of R-curves to study the frac ture be hav ior of high-strength con crete and steel-fiber-re in forced con crete sub jected to crack ing in a three-point bend ing con fig u ra tion. The R-curves are modeled through an ef fec tive ap proach based on the equa tions of lin ear-elas tic frac ture me chan ics (LEFM), which re lates the ap plied load to the fun da men tal dis place ments of notched-through beams loaded monotonically. It is ini tially shown that, for quasi-brit tle ma te ri als, the R-curves re sponses can be eval u ated in a quasi-an a lyt ical way, us ing the load-crack mouth open ing, the load-load line dis place ment, or ex clu sively the dis place ment re sponses ob tained ex per i men tally. Af ter ward, the meth od ol ogy is used to ob tain the frac ture re sponses of high-strength and fi ber-re in forced con cretes, up to the fi nal stages of rup ture.
Discrete fracture in high performance fibre reinforced concrete materials
Engineering Fracture Mechanics, 2011
In this paper a simple, but effective methodology to simulate opening mode fracture in high performance fibre reinforced concrete is presented. To obtain the specific fracture energy of the material, load-deflection curves from three point bending (TPB) experiments are extrapolated. The proposed extrapolation technique is an adaptation of an approach originally developed for plain concrete. The experimental part of the paper includes a size effect study on TPB specimens. The post crack behaviour of the material is modelled using a cohesive softening function with crack tip singularity. Numerical simulation of the experiments is performed by means of an embedded discontinuity method. The simulation provides satisfactory predictions of the fracture behaviour of the material and the size-effect observed in the experiments.