Steel Fiber Reinforced Concrete Structure Failure Analysis And Mechanical Properties Experimental Research

With the rapid development of the construction industry,concrete structures,steel structures and their traditional composite structures can no longer meet the engineering needs of special buildings.The design and application of new structures for complex structures has become a current research hotspot.Experts and scholars are studying new structures and expect to apply them to practical projects.In view of the low cost but weak tensile performance of concrete,and the excellent performance but high cost of steel-concrete structure,a new concrete structure,steel fiber reinforced concrete partially reinforced steel composite beam,is proposed.This new structure saves most of the concrete in the tensile zone,reduces the self weight of the structure and saves the cost,and gives full play to the performance advantages of steel and concrete.In order to study the failure mode and mechanical properties of this new type of structure under reciprocating load,seven types of steel fiber reinforced concrete partially reinforced steel composite beams were designed.The development of cracks and the final failure mode of the specimen during loading were compared and analyzed.Based on the load displacement curve and skeleton curve of the specimen,the volume ratio of steel fiber,the thickness of concrete upper protective layer The influence of the thickness of the protective layer under the concrete and the specification of the section steel on the bearing capacity,deformation,stiffness degradation and energy consumption of the specimens.The main conclusions of this thesis are as follows:(1)The bearing capacity of the specimen is mainly affected by the specification of the section steel.If the section steel with higher specification is configured,the bearing capacity of the specimen will be greatly improved;The increase of steel fiber volume ratio and the decrease of concrete cover thickness can also improve the bearing capacity of the specimens to a certain extent.For the specimen with bending failure,the deformation is mainly concentrated in the yield stage,and the least deformation is in the elastic stage;Except for bending failure,the deformation of other specimens mainly occurs in the failure stage,and the deformation in the yield stage is the smallest.(2)It shows that the size of section steel is the main factor affecting the strength of the specimen,and the volume ratio of steel fiber and the thickness of the upper and lower protective layers of concrete have little effect on the strength of the specimen.The ductility of specimens can be effectively improved by properly increasing the volume ratio of steel fiber and the thickness of protective layer under concrete.The stiffness of the test piece increases with the increase of steel fiber volume ratio,and high-specification section steel can also increase the stiffness of the test piece.With the increase of steel fiber volume ratio,the elastic deformation of the test piece can show a decreasing trend.(3)Steel fiber has a certain effect on delaying the stiffness degradation of the specimen,and increasing the thickness of the protective layer under the concrete can also delay the stiffness degradation,while changing the specification of steel has little effect on the stiffness degradation of the specimen.The elastic deformation energy of the specimen is related to the specification of the section steel.The small thickness of the concrete cover will greatly limit the energy dissipation capacity of the specimen.The energy dissipation capacity of the specimen with bending failure is much higher than that of other specimens.