Experimental Study On The Flexural Behavior Of Regionally Confined Concrete Beams

The regional constraints is that the steel bars formed by the longitudinal reinforcement and transverse stirrups provide a common constraint on the concrete according to the concept of regional confined concrete(RCC),the reinforcement cage is also tightly integrated with internal concrete to form an organic whole.Not only can it limit the lateral deformation of concrete after the constraint but also it can limit the shear deformation and torsional deformation of the core concrete inside the steel cage,which making the application of confined concrete has been greatly expanded.Setting stirrups in the middle of the concrete compression area to form a constraint in this area,the reinforcement ratio of the tensioned area reinforcement can be increased because of the increase of strength and ductility of concrete in confined area,thereby the ultimate bearing capacity and ductility of the beam has been improved.Reducing the height and weight of the beam under certain load conditions,then the cross-sectional dimension of the member can be reduced and structure of its own weight will be greatly reduced,which will save construction costs.Experimental study on static loading for five different forms of regional confined concrete beams(RCCB)based on theoretical analysis,the reaction of the structure under static load can be measured,which include cross-section stress,mechanical mechanism,load-deformation relationship,failure process and other mechanical properties.Then we can determine the structure working state and force situation to demonstrate the feasibility of different forms of regional confined stirrups and increase the longitudinal reinforcement size to increasing the flexural behavior.Experimental studies have shown that: Experimental studies have shown that:The regional confined concrete beam with the "ri" shape stirrups have good bending resistance,which concrete and steel mechanical properties have been fully developed and the failure mode is ductile failure.The destruction form of RCC beam with the "ri" shape stirrups is normal section failure but the oblique section failure from the RCC beam with the small square stirrup shape;the bearing capacity and ductility of the RCC beam with the "ri" shape stirrups is better than the normal concrete beam(NCB).It is found that the bending behavior of the RCC beam with the "ri" shape stirrups is the best considering the mechanical performance indicators.Finite element simulation analysis of regional confined concrete beams with abaqus software after the experiment is completed,analyzing the mechanical properties and failure process of the test beams under static load.The test phenomena of RCCB1,RCCB3 and NCB were compared with the simulation results in order to get the applicable Expansion angle,Viscosity coefficient and other finite element model parameters,and optimize the reinforcement of the beams that equipped with a small square stirrups according to the experiment to find out the better reinforcement way of regional confined concrete beam.