Reinforcing Cementitious Composite Open-Hole Plate Subjected to Uniaxial Tension Using Full-Field Aligned Steel Fibers

Opening holes in construction structures is used often to allocate electrical or ventilating lines. However, it may result in stress concentration and hence the reduction in mechanical properties. In order to manage these problems, an approach of preparing full-field aligned steel fiber-reinforced cementitious composites (FASFRC) around the hole is proposed to maximize the effect of reinforcement of steel fibers around the hole by aligning the steel fibers according to the direction of local tensile stress. Thus, the approach of preparing an open-hole plate using FASFRC is developed. The advantage of FASFRC in improving the uniaxial tensile performance of the open-hole is investigated by comparing the performance with that of specimens using ordinary steel fiber-reinforced cementitious composites (SFRC) and aligned steel fiber-reinforced cementitious composites (ASFRC). The evolution of the failure process of the specimens subjected to uniaxial tension is monitored using the digital image correlation (DIC) method, and numerical simulation is carried out to calculate the optimal fiber volume dosage around the hole and the stress concentration factor. The experimental results show that in the FASFRC specimens, the fibers are effectively aligned- the direction of tensile stress and more steel fibers are allocated in the area around the hole. The uniaxial tensile strength of FASFRC is 43% to 49% higher than that of SFRC and ASFRC with various fiber volume dosages. The tensile work and uniaxial tensile toughness ratio of FASFRC are 35%-52% and 7%-21% higher than that of SFRC and ASFRC. The full-field deformation obtained from DIC shows that FASFRC tends to exhibit multicracking and strain-hardening behavior, which are different from SFRC and ASFRC. The modeling results have good agreement with the tests for various types of specimens; hence, the numerical simulation on the uniaxial tensile test of FASFRC is reliable. The numerical results show that the optimal fiber volume dosage in the area around the hole for FASFRC is 2.0% (the corresponding fiber volume dosage in other area is 1.0%). This investigation provides an option for improving the mechanical properties and alleviating the stress concentration of open-hole structures without increasing total steel fiber dosage.