Experimental Study On Reinforcement Of Self-Compacting GHPFRCC Beams With Fire Damage

Self-compacting GHPFRCC(green high-performance fiber-reinforced cementitious composites)not only continues the characteristics of ECC’s(Engineered Cementitious Composites)high tensile toughness,superior crack control ability and high energy consumption,but also has the advantages of vibration-free construction and good workability.With the rapid development of society,my country’s construction industry has gradually entered a period of building modernization and maintenance and reinforcement.At present,the building structure reinforcement and transformation industry has become a new development hotspot in my country’s construction industry.Compared with traditional reinforcement methods,self-compacting GHPFRCC has high toughness and excellent tensile performance,and it is convenient for vibration-free construction.In order to promote the reinforcement method in actual reinforcement,this article mainly does the following researches:(1)Nine test beams were designed,of which two were GHPFRCC beams and the rest were all C30 concrete beams.Five C30 concrete beams and one GHPFRCC beam were subjected to fire test,and two fire-damaged beams and two contrast beams were selected for static load test.The data such as the fire temperature field distribution of the component obtained from the fire test and the load-displacement curve after the static load test provide the basis for the subsequent reinforcement of the beam.(2)Determine the cutting depth of old concrete based on the component fire temperature field distribution and the load-displacement curve after the static load test,and determine the reinforcement plan based on the principle of equal strength.(3)Determine the static load test plan of the strengthened specimen,study the shear and flexural properties of the self-compacting GHPFRCC reinforced fire-damaged beam.Through the comparative analysis of load-displacement curves,the results show that:(1)After self-compacting GHPFRCC reinforced fire damaged specimens,the ultimate bearing capacity of the specimens is restored or even improved,and the reinforcement effect is good.(2)The ratio of stirrups has little effect on the shear resistance of the reinforced specimens.Self-compacting GHPFRCC can replace part of the stirrups to resist shear.(3)After the self-compacting GHPFRCC is strengthened on three sides,the ultimate flexural bearing capacity of the specimen is increased by 43.6%.The self-compacting GHPFRCC can increase the flexural rigidity of the beam after fire damage and improve the flexural performance of the beam.(4)After the self-compacting GHPFRCC is strengthened,the strain of the self-compacting GHPFRCC is linearly distributed from the initial loading stage to before the beam cracks,which satisfies the assumption of flat section.After the beam cracked,the development of the cracks affected the strain growth rate at the measuring point.After that,the strain curve changed roughly linearly,basically satisfying the assumption of a flat section.(4)Based on the experimental basis,ABAQUS is used to simulate the reinforced specimens,and at the same time,the shear and flexural properties of the reinforced beams are analyzed theoretically.The results show that the calculated bearing capacity is in good agreement with the experimental value;The ratio has little effect on the shear capacity of the self-compacting GHPFRCC reinforced beam;as the replacement thickness of the tension zone increases,the flexural capacity of the beam gradually increases.