Influence of fiber content on compressive low-cycle fatigue behavior of self-compacting SFRC

Significance Statement

Steel-fiber reinforced concrete is a composite material that is composed of steel fibers distributed in the matrix of the concrete. The fibers are responsible for improving flexural strength and limiting cracks formation. In addition, the benefits of the steel-fibers in tension cannot be overemphasized. Unfortunately, in compression, little has been researched concerning the effect of fiber content particularly when it comes to fatigue. In fact, for the little that has been researched, there is a scarce variety of compositions and limited number of tests.

A number of studies have been done emphasizing the benefits of fiber in compressive fatigue behavior, but many have not focused on the effect of the amount of fibers on the fatigue life. Some have also not focused on the loading frequency of the tests. However, it is necessary to emphasize that concrete fatigue tests present a great dispersion of results, which may even reach two orders of magnitude for particular stress levels. Therefore, it becomes necessary to resort to a number of tests for which statistical distribution will be pegged to restricted cycles.

Elisa Poveda, Gonzalo Ruiz, Rena C. Yu and Xiaoxin Zhang at Universidad de Castilla-La Mancha in collaboration with Héctor Cifuentes at Universidad de Sevilla in Spain designed a robust self-compacting matrix for low and high fiber amounts while guaranteeing sufficient workability as well as good fiber matrix adherence in all the dosages. This therefore fulfilled the requirements of fresh self-compacting concrete. Their main aim was to establish the optimum fiber content in the low-cycle compressive fatigue and the effect of the dosage on the cyclic creep curve as a parameter that identifies fatigue damage. Their research work is published in  International Journal of Fatigue.

The authors analyzed the effect of fiber content in steel-fiber reinforced concrete on the mechanical attributes under low cycle fatigue. The authors therefore prepared five types of self-compacting concrete with varying fiber content, varying from 0 to 0.8% in volume. They maintained the same concrete matrix while guaranteeing the adherence and flowability between fibers and the matrix in all dosages. As opposed to other fatigue studies, this one provided a complete characterization of the materials.

In the static behavior, the authors observed that the fibers did not produce appreciable improvement in compressive strength. However, fibers produced a more gradual softening after the maximum load. Increasing the fiber content enhanced the post peak flexural behavior.

The researchers observed that increasing the amount of steel fibers improved the compressive fatigue behavior. This is because the fatigue life of concrete improves when fibers are added. Concerning the fiber content, in plain concrete, low amount of fiber did not give more improvement in the fatigue attributes. However, intermediary contents led to fatigue life that was five times longer than that of plain concrete. The dosage that resisted a good number of cycle was that of the intermediary content, that of 45kg/m3 followed by that of 30kg/m3. However, increasing the fiber content past the optimum content led to shortening of the fatigue life. This is referenced to the fact that high fiber content distorted that matrix and produced pores as well as imperfections that favored crack initiation.

The authors also verified that the relationship between the secondary strain rate per cycle with the fatigue life was independent of the amount of fibers, and therefore depended on the matrix only. Based on the results obtained, the authors proposed a strain-based fatigue failure criterion entailing mechanical as well as time-dependent deformation.

Influence of the fiber content on the compressive low-cycle fatigue behavior of self-compacting SFRC. Advances in Engineering

About the author

Elisa Poveda Bautista is an assistant professor at the University of Castilla-La Mancha. She received her PhD and MSc degree from the School of Civil Engineering at the same university and her BS degree from the Polytechnic University of Valencia. Her research interests include numerical study on the static and dynamic behaviour of plain and reinforced concrete (multi-scale), characterization of the mechanical properties of fibre-reinforced concrete under fatigue and impact loadings and proportioning of self-compacting steel-fibre reinforced concrete mixes.

She has co-authored 6 peer-reviewed journal articles and two patents. She is member of different committees about fatigue in concrete (ACHE) and modelling of fibre reinforced concrete structures (work group 2.4.2) of the fib. She has co-organized the 8th International Conference on Fracture Mechanics of Concrete and Concrete Structures (FraMCoS-8) and different workshops on fiber reinforced concrete. Email: [email protected]

About the author

Gonzalo Ruiz

Professor of Materials Science and Civil Engineering at the Civil Engineering School of the University of Castilla-La Mancha, Ciudad Real, Spain. He was Visiting Associate at Caltech, USA, and Guest Professor at Harbin Engineering University and Zhejiang University, China.

He leads the group of Solid Mechanics —Experimental and Computational— at the University of Castilla-La Mancha. His research focuses on the mechanical properties of civil engineering materials, mainly concrete and reinforced concrete. He is currently working on the analysis of the nucleation and propagation of fracture processes in fiber reinforced concrete. He is also interested in the characterization of the fatigue life of high performance fiber concrete.

Prof. Ruiz is a founding member of the Spanish Society of Structural Integrity. He was the Secretary of the International Association for Fracture of Concrete and Concrete Structures, IA-FraMCoS (2010-2016) and is the Treasurer of the European Society of Experimental Mechanics (EuraSEM). He is Delegate of Spain in Committee CEN TC250/SC2/WG1/TG2, which is writing the Annex on fiber concrete of Eurocode 2. He served as Manager of the Spain National Research Program on Construction (State Secretariat for RD and Innovation, Spain) during the period 2009-2016. Prof. Ruiz is the Editor-in-chief of Hormigón y Acero, Journal of the Spanish Society of Structural Engineers, Edited by Elsevier.

About the author

Héctor Cifuentes (born December 1975, Asturias, Spain) received his Master of Science (Mechanical Engineering) from the University of Seville and the Doctor of Philosophy degree from the same University. He currently holds the position of associate professor of reinforced concrete and composite steel-concrete structures. He also participates as guest professor in different seminars and courses related to the structural behavior of concrete.

His major research interests are the mechanical and fracture behavior of high- and ultra-high-performance fibre-reinforced cement-based materials, the fatigue behavior of fibre-reinforced concrete under different loading (compressive and flexural), the thermo-mechanical behavior of concrete structures, the computational fracture mechanics of quasi-brittle materials and the experimental and numerical analysis of steel-concrete composite slabs. He is the author of several papers published in well-reputed journals of engineering relative to his research areas of interest and he participated in many international conferences. Since 2016, he is one of the associate editors of “Hormigón y Acero”, a quarterly Spanish journal that has been issued since 1950.

About the author

Dr. Xiaoxin Zhang is an INCRECYT permanent researcher in the Scientific and Technological Park of Castilla La-Mancha, and also the technical director of the Lab of Materials and Structures of the University of Castilla La-Mancha, Spain. He got his PhD on Materials Science in Harbin Engineering University in 2004, China. In 2005, He incorporated into the research group of Prof. Gonzalo Ruiz.

His main research interests are as follows: dynamic behavior of materials at high strain rates, fatigue behaviors of metal, concrete, fiber-reinforced concrete and concrete structures.

He was a member of scientific committees of FraMCos-8 (8th International Conference of Concrete and Concrete structures, held in Toledo, Spain, 2013), ICEM-16 (16th International Conference on Experimental Mechanics, held in Cambridge, UK, 2014), ICEM-17 (held in Rhodes, Greece, 2016), respectively. Moreover, currently, he is a “Seasky Scholar” (Visiting Professor) of Dalian University of Technology (DLUT, China).

About the author

Dr. Rena C. Yu, graduated with a BSc in Aeronautics from Beijing University of Aeronautics and Astronautics China in 1994. She received a master and PhD degree from California Institute of Technology, USA in 1997 and 2001 respectively. She joined the University of Castilla-La Mancha in 2001 first as a postdoc scholar then a Ramon y Cajal researcher and became an associate Professor in the same university in the area of Continuum Mechanics in 2007. She was appointed as adjunct associate professor at Zhejiang University (2015-2018).

She has published more one hundred scientific papers published in top international journals such as Journal of Mechanics and Physics of Solids, International Journal of Impact Engineering, Cement and Concrete Research, International Journal for Analytical and Numerical Methods in Geomechanics. She has supervised five PhD thesis and directed several national and regional projects. Her research interests lies in the numerical modelling of dynamic fracture in cementitious materials through traditional finite element methods and meshfree approaches.

Reference

Elisa Poveda, Gonzalo Ruiz, Héctor Cifuentes, Rena C. Yu, Xiaoxin Zhang. Influence of the fiber content on the compressive low-cycle fatigue behavior of self-compacting SFRC. International Journal of Fatigue, volume 101 (2017), pages 9–17.

 

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