Study On Constitutive Relation Of Steel Basalt Hybrid Fiber Concrete

Fiber reinforced concrete is considered to be one of the most widely used engineering materials in the field of civil engineering,and the research on its fracture behavior has always been the focus of attention.Since its emergence,fiber reinforced concrete has been widely used in Bridges,airways,road surfaces,underground tunnels and other practical projects.In these projects,the fracture behavior of fiber reinforced concrete is an important index for quality control and structural design.Therefore,the study of fracture properties of fiber reinforced concrete has very important practical engineering application value and theoretical significance.Concrete softening constitutive curve is the basis of concrete fracture model,which is mainly used to describe the characteristics of the fracture process zone,and the fracture energy and softening curve of concrete are the necessary input parameters in the process of finite element simulation of concrete nonlinear performance.Therefore,it is of great significance to obtain the softening constitutive curve of concrete accurately and conveniently,and to study the fracture characteristics of concrete.In view of this,this article adopts the method of theory with practice,through compression test,splitting tensile test and three point bending test,studied the fracture properties of steel-basalt hybrid fiber reinforced concrete,and combined with bilinear softening curve model obtained by back analysis of ABAQUS steel and basalt hybrid fiber concrete softening constitutive curve parameter,the main work and achievements are as follows:(1)The mixing of basalt fiber and steel fiber has a good positive mixing effect on the compressive strength and splitting tensile strength of concrete.For the compressive test,when the steel fiber content and basalt fiber content are 1.6% and 0.05%,respectively,the compressive strength of steel-basalt hybrid fiber concrete test block increases by 47%,and the effect is better.For the splitting test,when the basalt fiber and steel fiber contents are 0.1% and 1.3%,respectively,the tensile strength of steel-basalt hybrid fiber concrete test block increases by 44%,and the effect is better.(2)The P-CMOD curves of each group of specimens were obtained through the three point bending test,and the fracture energy and fracture toughness of each group of specimens were calculated.It is found that the mixing of basalt fiber and steel fiber has a good positive mixing effect on the fracture energy and fracture toughness of concrete.Especially when the steel fiber content is 1.6% and basalt fiber content is 0.1%,the fracture energy and fracture toughness of steel-basalt hybrid fiber increase by 129% and56%,respectively,compared with that of single SFRC,which shows better effect.(3)The P-CMOD relationship of the three-point bending-gap beam was simulated by ABAQUS finite element software,and the material parameters of bilinear softening relationship of steel-basalt hybrid fiber concrete were determined by back analysis.