Investigation on the performance of annularly aligned steel fiber reinforced cementitious composites pipe under internal water pressure

Steel fiber reinforced concrete pipes are commonly used in the municipal, agricultural, and industrial fields because of their superior internal water pressure performance. However, the randomly distributed steel fibers hinder the further improvement of internal water pressure performance. To maximise the reinforcement effect of steel fibers and improve the internal water pressure performance, an external circular magnetic field was first utilised to prepare annularly aligned steel fiber reinforced cementitious composite (AASFRC) pipes in which the steel fibers were aligned in the direction of tensile stress. Subsequently, the internal water pressure performance of AASFRC and steel fiber reinforced cementitious composite (SFRC) pipes was experimentally and numerically investigated. Finally, the reinforcement mechanism of the annularly aligned steel fibers was revealed from the aspects of fiber distribution and fiber resultant force. The results showed that the deformation and bearing capacity were enhanced by annularly aligned steel fibers. The ultimate internal water pressure of the AASFRC pipes was greater than that of the SFRC pipes by 22–32% with fiber volume fractions (Vf) of 0.8%, 1.2%, and 1.6%, implying that using less fiber in AASFRC pipes can ensure an internal water pressure performance equivalent to that of SFRC pipes. Both the fiber orientation efficiency factor and number of fibers bridging the principal cracking section of the AASFRC pipes were greater than those of the SFRC pipes. The fiber resultant force of AASFRC specimens was 2.04–2.64 times greater than that of SFRC, contributing to the enhancement in the bearing capacity of AASFRC pipes.