Compressive behavior of reinforced steel-PVA hybrid fiber concrete short columns after high temperature exposure

To investigate the axial compression mechanical properties of steel-PVA hybrid concrete short columns after high temperature, three groups of 15 specimens (without or mixed with steel and PVA fibers) were tested in this paper. These specimens were subjected to quasi-static loading compressive loading after exposure to elevated temperature. The results indicated that as the temperature increased, the hydration reaction occurred in the concrete, and specimen surface color gradually changed from light gray to grayish white, and its mass loss rate gradually increased. The mechanical properties of short columns of hybrid fiber concrete were significantly affected by the elevated temperature. However, the compressive bearing capacity of specimens was increased by the mixed fibers after elevated temperatures, compared to the ordinary concrete. Meanwhile, specimen with more steel fibers performed better on bearing capacity. The PVA fiber effectively reduced the formation and expansion of cracks in hybrid fiber concrete after high temperature and enhanced its ductility. A suggested reduction coefficient was introduced by considering the influence of temperature and fiber volume ratio, and the calculated value of axial compression bearing capacity of the specimen was in good agreement with the experimental value.