Experiment Study and Finite Element Analysis of the Coupling Effect of Steel Fiber Length and Coarse Aggregate Maximum Size on the Fracture Properties of Concrete

The effects of steel fiber length (l(f) = 30 mm, 40 mm, 50 mm and 60 mm) and coarse aggregate maximum size (D-max = 10 mm, 20 mm, 30 mm and 40 mm) on fractural properties of steel fiber reinforced concrete (SFRC) was investigated. The results show that the fracture energy (G(f)) of SFRC reaches its maximum when D-max increases to 30 mm, and it increases first and then decreases as lf increases, but it still has a significant increase compared to the control concrete. The G(f) ratio increases first and then decreases as the l(f)/D-max increases. The G(f) of the SFRC fracture surface follows the same trend as the fractal dimension. The rational range of the l(f)/D-max is 2.5-4 for the considerable strengthening effect of steel fiber on fracture performances of concrete with the D-max of 10 mm and 20 mm and 1.5-2.33 for that concrete with the D-max of 30 mm and 40 mm. The finite element analysis results are compared with the experimental results, and the results show that the fracture process of the finite element model is consistent with the experiment.