Study On Axial Compression Performance Degradation Of Spiral Stirrups Confined Concrete Columns Cooled By Water Spray After High-temperature

Spiral stirrups confined concrete structure is known for its excellent mechanical performance and is gradually applied to practical engineering.In this study,the behavior of spiral stirrups confined reinforced concrete columns under axial compression after high-temperature is investigated and analyzed.Twenty-three specimens of spiral stirrups confined reinforced concrete columns were designed,of which twenty were high-temperature specimens and three were normal temperature specimens.Highest temperature(later called temperature),stirrup spacing,and cooling mode is the main parameters,and the axial pressure was applied to the specimens.In the investigation,the physical changes and failure modes of the specimens were observed after high temperature.The peak load,peak displacement,and load-displacement curves of the specimens were obtained.The effect of high-temperature on the mechanical properties of specimens is revealed.The experimental results show that with the increase of temperature,the surface color of the specimen changes from goose yellow to gray-white,and the mass loss increases.For different cooling mode,the ignition loss rate of the specimens under nature cooling is obviously higher than spray cooling.With the increase of temperature,the earlier the cracking time,the more serious the buckling phenomenon,the lower the bearing capacity of the specimen,and the change trend of peak displacement is slow then rapid growth.For the specimens with a large spacing of spiral stirrups,the cracks appear earlier,the more serious the concrete breaks,and the specimens with a small spacing of spiral stirrups,the more obvious the phenomenon of compression and bending,and the phenomenon of necking and breaking of stirrups appear.Generally speaking,the specimens with 30 mm spacing of spiral stirrups have better displacement deformation ability when cooled naturally,and the specimens with 50 mm and 70 mm spacing of spiral stirrups have better displacement deformation ability when cooled by spraying water.The research program was planned to fill the identified gaps in the existing literature on the subject and to provide data which could help reveal the fire resistance of the concrete structure and laid the foundation for the post-disaster detection and repair work.