Fracture Energy of Steel Fiber-Reinforced Concrete
Steel fiber-reinforced concrete (SFRC) is a cementitious material reinforced with discrete fibers. The energy absorption capacity is the main material property benefited by fiber reinforcement. Closed-loop servo-controlled equipment should be used to evaluate this property. The tests should be carried out using displacement control in order to obtain the postpeak force- displacement relationship (tensile strain-softening branch). To assess the fracture energy of SFRC, three-point bending tests were carried out using displacement control. Series of notched beams reinforced with 30, 60, and 90 kg/m3 of hooked-end steel fibers were tested. Besides the energy dissipated in fracturing the concrete, the energy determined from the force-displacement relationship can also include the energy absorbed during nonlinear behavior of concrete in compression. Ductile materials, such as concrete reinforced with a high content of fibers, develop large deflections before exhausting their energy absorption capacity. In these cases, the "fixed" points of the bar supporting the displacement transducer may not remain fixed, adding an extra deflection into the control displacement transducer and thus leading to incorrect evaluation of the fracture energy. These factors are analyzed in the present work in order to assess the suitability of the specimen dimensions and the test procedures for evaluating the fracture energy of SFRC.
Experimental behaviour of fibre concrete slabs on soil
The cracking control of plain concrete slabs on soil foundation requires the execution of joints with mechanisms of load transfer between adjacent panels. These joints increase the construction costs and, often, are the source of local damage and loss of service performance. Slabs reinforced with steel wire mesh have been used in order to increase the load-carrying capacity and to enhance the cracking control. However, the use of this conventional reinforcement increases the costs, mainly due to labour time spent on the arrangement and positioning of the reinforcement. 
 
 
 
Fibre-reinforced concrete is a recent material well fitted for applications in industrial floors on soil foundation. The cost of fibres is compensated by a faster construction process and a reduction in the number of expansion joints. The fatigue, impact and flexural strength are significantly improved when steel fibres are added to the concrete mix. 
 
 
 
The work developed aims to contribute to the on going research effort to clarify the behaviour of fibre-reinforced concrete slabs on soil foundation. For this purpose, an experimental and numerical investigation were carried out. The present article deals basically with the experimental work developed, describing the tests performed and discussing the main results obtained. © 1998 John Wiley & Sons, Ltd.
Flexural Behavior of SFRC: Testing and Modeling
In this paper the results of tests performed on specimens and structural elements made of steel fiber reinforced concrete (SFRC) are presented. Fiber content of the concrete ranged from 0 to 60 kg/m³. Using the results of the uniaxial compression tests performed under displacement control condition, a stress-strain relationship for fiber concrete in compression was derived. Three-point bending tests on notched beams were carried out to simulate the postcracking behavior and to evaluate the fracture energy. Based on the constitutive relationships derived from the experiments, a layered model for the analysis of steel fiber reinforced concrete cross sections was developed. The model performance and the benefits of fiber reinforcement on thin slabs reinforced with steel bars were assessed by carrying out tests on slab strips. The main results are presented and discussed.