Experimental Research On Bending Performance Of SFRC Reinforced SCC Reinforced Composite Beam

The rapid development of construction science and technology makes the building itself have increasingly higher requirements for building materials.Traditional concrete has prominent defects such as poor crack resistance,low tensile strength and poor durability when it is used in civil,defense and industrial buildings.In order to reduce the disturbance to the reinforcement in the densely reinforced area of the structure when pouring concrete,Self Compacting Concrete(SCC),which can be self-leveled under the effect of its own weight,has appeared in the project;Steel fiber reinforced concrete(SFRC)is also widely used in water conservancy and hydropower,port and port,etc.due to its excellent toughening and cracking resistance.Engineering under construction.In this paper,on the basis of ordinary reinforced concrete beams,based on the excellent performances of SFRC and SCC,a number of reinforced composite beams with tension zone SFRC and compression zone SCC are designed and manufactured;on the basis of basic mechanical properties tests of materials,Four-point bending load test study was conducted on the composite beam to analyze the longitudinal reinforcement ratio,steel fiber volume content and SFRC replacement height in the tensile zone.For SFRC reinforced SCC composite beam under four-point bending load,the load,deflection,The influence of basic properties such as the development trend of cracks,and the theoretical analysis and comparative study of the bending capacity,deformation and crack calculation of the composite beams.The specific conclusions are as follows:1)The compressive and split tensile strength test results of SFRC and SCC cubes show that: the increase of the volume content of steel fibers can increase the compressive strength of SFRC to a certain extent.The improvement of concrete compressive strength is only 5.51% and 7.05%,and the corresponding splitting tensile strength is increased by 6.70% and 8.01%,respectively.The performance is mainly reflected in the workability of the freshly mixed mixture.The basic mechanical properties of the hardened product are no different from ordinary concrete of the same strength level.2)In the bending performance test of composite beams,the first cracks will appear in different positions due to the different SFRC replacement heights in the tensile zone.The first cracks of composite beams with a small replacement height(?50mm)will appear at the edge of the material interface on the section SCC At the fiber area,the reverse occurs at the SFRC fiber at the bottom edge of the beam;and the crack form of the composite beam is thin and dense in the tensile zone when the composite beam finally fails,and the macroscopic form of 1 to 3 main cracks is formed in the compression zone.3)The mechanism of increasing the replacement height of SFRC in the tensile zone is the same as that of increasing the volume of steel fiber in SFRC,both of whichcan better exert the toughening and crack resistance of steel fibers randomly distributed between cracks.The width and spacing are reduced and the number of cracks is increased.4)The increase of the SFRC steel fiber volume content and the SFRC replacement height in the tensile zone of the composite beam will reduce the error between the theoretical analysis results of the composite beam ultimate bearing capacity,deflection and cracks and the actual test results.