Research on mechanical property of SFRC was done through experiments of two SFRC Tbeams and one concrete Tbeam, while the influences of different volume fractions of steel fibers on integral rigidity, ultimate shear capacity, and the crack distribution characteristics were analyzed. ANSYS finite element software was used to simulate the tests and it was found that there was good conformation between the results of ANSYS simulation and tests. The test results and finite element software simulation both showed that the incorporation of steel fibers in the concrete can increase the integral rigidity and ultimate shear capacity, while partially reducing the propagation of cracks effectively. It was also proved that it is reliable to simulate SFRC Tbeam by ANSYS software.
Tbeam is very commonly used in the Chinese highway bridges, where the crackle status is very serious in Tbeams. With the wide usage of the traditional concrete, some obvious shortcomings are exposed gradually, such as low strength, poor ductility, and the brittle failure under the impact load. These shortcomings will limit the application of concrete in the future structure. If some steel fibers are added in concrete, fiber can not only prevent the development of concrete cracks but also improve the flexural, shear, and tensile properties of concrete [
Steel fiber reinforced concrete (SFRC) has a good crack resistance, so it is widely used in the fields of airport pavement, bridge deck, and waterproof roof. But now there are not a lot of researches on the shear performance and crack resistance effect of SFRC Tbeam. In this paper, a concrete Tbeam and two SFRC Tbeam specimens were designed to investigate the effect of steel fiber content on the bearing capacity of concrete Tbeam to understand the characteristics of SFRC in shear and crack resistance.
In this test, three test Tbeams were prepared, one threemeter (length) ordinary concrete Tbeam and two threemeter (length) SFRC Tbeams. The parameters of specimen are shown in Table
Test Tbeam parameters.
Material  Beam node  Stirrup spacing 
Stirrup ratio  Volume fraction of steel fiber 

Concrete  1  150  0.48%  0 
SFRC  2  150  0.48% 

SFRC  3  150  0.48% 

Section size and reinforcement layout (unit: mm).
In this experiment, a tape of waved steel fibers produced by Suzhou Longyu Co., Ltd., with 792 MPa tensile strength, 30.18 mm fiber length, 0.91 mm equivalent diameter, and 33aspect ratio, was used. The mechanical properties of concrete and the reinforced bar are shown in Tables
Mechanical properties of concrete.
Beam node  Crushing compressive strength  Concrete compressive strength  Young’s modulus 

1  37.1  28.2  31.9 
2  40.3  30.6  32.7 
3  40.5  30.8  32.7 
Mechanical properties of reinforced bar.
Steel grade  Bar diameter  Yield stress  Ultimate stress  Young’s modulus 

HPB235  8  342  500  210 
HRB235  28  389  574  200 
In the test, the method of twopoint loading was used by the distributive beam. The shear span ratio was 2. The support of the beam was 225 mm far from the beam end, and the loading device was a separate type of hydraulic jack that used a highprecision static servohydrauliccontrol system. Gradation loading was acted on the beam, and the holding time was 15 minutes. In the process of loading, the crack occurrence and development should be carefully observed.
Displacement gauges were arranged in the support, 1/4 points, and the midspan. In each loading process, the corresponding load and displacement values were recorded synchronously.
The crack load (
Summary of shear resistance of beams.
Beam node 




1  200  830  10.77 
2  400  1150  18.9 
3  300  >1200  7.6 
Loaddisplacement curve of the beams.
Three test Tbeams were carried out under 200 KN, 500 KN, 800 KN, 1000 KN, 1100 KN, and 1200 KN. The results are shown in Table
The development status of the maximum crack width (unit: mm).
Node  Load  

200 KN  500 KN  800 KN  1000 KN  1100 KN  1200 KN  
1  0  1.6  2.5  —  —  — 
2  —  0.2  1.5  3.31  >4  — 
3  —  0.1  0.5  0.63  1.5  — 
Crack diagram of each beam.
Crack diagram of 1# beam
Crack diagram of 2# beam
Crack diagram of 3# beam
When ANSYS was used for finite element analysis of reinforced concrete, a separate model was adopted. The concrete was simulated by Solid 65 element and steel bar was simulated by Pipe 59 element. The bond slip between the steel fiber and concrete was neglected.
This paper established the 1/2 Tbeam model, which can not only reduce the calculation time but also avoid terminating the calculation during calculation process due to too many warnings. In the finite element simulation, the stress concentration was avoided at the support and the loading point by adding an elastic pad. The ANSYS model is shown in Figure
ANSYS model.
Finite element solid model
Reinforced element model
Finite element mesh
The doubleline strong hardening model (BISO) was used in the constitutive relation of the steel bar, and the formula about uniaxial compressive stressstrain curve of concrete [
Constitutive relation of concrete is as follows:
Ascending stage is
Descending stage is
In the formula,
Constitutive relation of SFRC is
In the formula,
The comparisons of test data with ANSYS simulations are shown in Figure
Comparison of the results of test with ANSYS simulation.
1# beam comparison diagram
2# beam comparison diagram
3# beam comparison diagram
Test results
ANSYS results
The cracking load and ultimate load of three test Tbeams are shown in Table
Cracking load and ultimate load of three test Tbeams.
Beam note 







1  200  213  1.065  830  810  0.976 
2  400  364  0.91  1150  1270  1.104 
3  300  411  1.37  >1200  1420  <1.183 
According to the 1–3# beam, it can be seen that the loaddisplacement curve of the finite element is basically consistent with that of the test, and the gap of the failure load is not big. But the slope of the curve obtained by finite element method is slightly larger than that of the test chamber. The stiffness of the SFRC beam simulated by the finite element is slightly more than that of the test result. The main reason for this situation is the simulation of concrete inner and SFRC inner was ideal and with no flaw. In addition, due to the compacting process of beams in the actual process, the stiffness of the beam simulated by ANSYS is greater than that of test Tbeam.
ANSYS simulation results showed that the test Tbeam in the process of loading had experienced two stages, elastic and inelastic, along with the increase of load. The slope of the loaddisplacement curve was gradually reduced. The loaddisplacement curve obtained from the test also reflected the process of the stiffness degradation.
The volume fraction of steel fiber of 1#, 2#, 3# test Tbeam, respectively, was 0, 1.5%, and 2%. From Figure
From Table
From Table
The smeared crack model was used in ANSYS to simulate the distribution and development of cracks, with the lack of ability to simulate single fracture of crack width and crack development. From the crack distribution, it can be seen that the ordinary concrete beam cracks and SFRC beam cracks almost distributed in the whole beam section, and the results gained from half length of the beams were compared in Figure
Finite element simulation and test results of the cracks of each beam.
Finite element simulation results and test results of 1# beam cracks
Finite element simulation results and test results of 2# beam cracks
Finite element simulation results and test results of 3# beam cracks
From the crack distribution, it can be seen that the main crack spacing of beam 1 is smaller than that of beam 2 and beam 3. In Figure
The crack width of beam 1, beam 2, and beam 3 is compared in Table
Through the above test and finite element simulation analysis, the following conclusions can be drawn:
The incorporation of steel fiber can improve the integral rigidity and ductility of concrete Tbeam. In a certain range, the higher the volume fraction of steel fiber is, the higher the integral rigidity is and the slower the stiffness degradation of Tbeam is.
With the same reinforcement ratio and shear span ratio, the higher volume fraction of steel fiber is, the higher the ultimate shear bearing capacity of the concrete Tbeam is.
The increase of volume fraction of steel fiber can delay the development of cracks and make the distribution of cracks more uniform and also improve crack resistance of the concrete Tbeam when volume fraction was less than 2%.
Finite element analysis of SFRCTbeams by ANSYS is feasible, and the results obtained by ANSYS are in good agreement with test results. ANSYS can simulate the general trend of the crack and the crack distribution area of the Tbeam by using the smeared crack model.
The authors declare that they have no conflicts of interest.
The research described in this paper was financially supported by the Jiangsu Province Key Laboratory of Structure Engineering, located in Suzhou University of Science and Technology.