Research On Mechanics And Cracks Self-monitoring Performance Of Steel Fiber Reinforced TRC And Concrete

The weak tensile performance of concrete makes it often work with cracks in the serviceability stage,and the expansion of cracks will make the steel bars inside the concrete structure easy to be exposed to the external environment,and directly contact with aqueous solutions,oxygen,etc.,resulting in corrosion and weakening.The load-bearing capacity of the concrete structure in turn causes economic losses.In view of the problem of easy cracking of concrete and insufficient durability,on the one hand,high-performance materials such as basalt,glass,and carbon fiber textile can be developed to partially replace the rusty steel;on the other hand,steel fibers added to the concrete can also protect concrete structures by bridging the cracks and limiting the development of cracks.The structural health monitoring technology emerged in recent years can also assist in structural maintenance by sensing damage and cracks in concrete structures.Based on this background,this article explores the mechanical and crack self-monitoring performance of basalt fiber textile reinforced concrete short steel fibers and Macro steel fiber reinforced concrete.The main contents are as follows:With reference to relevant specifications,the slump,air content,and compressive strength of fine aggregate concrete were tested,and the influence of short fiber on the compressive strength of concrete was studied.The test results show that the incorporation of short fibers has no obvious effect on the compressive strength of concrete,but it will improve the compressive toughness of concrete and reduce the working performance of concrete.Through the axial tensile test of TRC,the mechanical properties and self-monitoring performance of cracks under the uniaxial tension are explored.Specifically,the tensile test of the basalt fiber textile and the axial tensile test of TRC were carried out.The research variables include the textile ratio,the content of short fiber and the prestress level.The research results show that: increasing the textile ratio and the content of steel fiber can increase the tensile toughness of TRC,and adding short steel fiber can reduce the gauge factor of TRC.The mixing of short steel fiber and PP fiber has a positive hybrid effect on the tensile toughness and the tensile gauge factor of TRC.Through the three-point bending test and crack monitoring test of TRC,the influence of the textile ratio,short fiber and prestress level on three-point bending performance was explored.The test results show that increasing the textile ratio and the content of steel fiber can increase the bending toughness of TRC,and adding short steel fiber will reduce the bending gauge factor of TRC,and the crack width can be estimated by establishing the functional relationship between FCR and COD.The mixing of short steel fiber and PP fiber has a positive hybrid effect on the flexural performance and bending gauge factor of TRC.Based on the flexural performance test of Macro steel fiber reinforced concrete,the influence of Macro steel fiber on the compressive strength,flexural performance and crack self-monitoring performance of concrete is studied.In addition,the existing research is limited to small-sized components,the influence of large-span electrode spacing and steel bars on the self-monitoring performance of fiber reinforced concrete are studied.The research results show that: the incorporation of steel fiber will not change the limit of proportionality flexural strength of fiber reinforced concrete,but it will enhance the flexural toughness of concrete;the incorporation of steel fiber will reduce the gauge factor of concrete,and the gauge factor of concrete will gradually decrease with the development of cracks;it is difficult for reinforced concrete to accurately locate the concrete cracks.The larger the electrode spacing,the smaller the corresponding FCR change.The FCR will change significantly at the moment when the steel bar is broken.