Experimental And Theoretical Research On Shear Performance Of Regional Confined Concrete Beams

With the continuous development of high-rise and super high-rise building,reinforced concrete beam at low stories of the building tend to withstand greater shear force as well as bending moment,which would result in brittle shear failure along the oblique section.In order to avoid brittle failure in this section,different structural measures were used to prevent or delay the phenomenon from happening,but often at the expense of the enlarged section or reinforcement ratio,which is inconsistent with the designing factors of the structure.Regional confined concrete(RCC),in which each region can work as an individual member,changed the traditional constraint condition.Owing to the change of the shear failure mechanism,the confined region can remain intact when the member broken,the ultimate shear capacity of the beam was increased to a certain extent.As a result,the brittle failure of reinforced concrete beam under shear load was effectively improved.Firstly,in order to analyse the shear performance of regional confined concrete(RCC)beams under different stirrup forms with shear-span ratio 1.13,experimental researches were conducted by tests of 4 RCC beams and 1 conventional confined beam,analyzing the shear performance and various factors exert on shear capacity under shear load simultaneously.The experiment revealed that ultimate bearing capacity and ductility of integral RCC beams were obviously increased.The separated RCC beams ensured bearing capacity as well as material dosage.Compared with the mechanics model of shear strength mentioned in Technical code for regional confined concrete structures that the RCC improved the resisting shear capability and the hypothesis of using the confined section as a whole to resist shear force proved to be right.By using the RCC constitutive relationships,nonlinear finite element analysis of the 5 beams under shear load has been made to simulate the whole process of the experiment,in which damage evolution,steel stresses and load-deformation curve were detailedly analysed.It proved that conclusion given by the nonlinear finite element analysis software of ABAQUS is consistent with the experiment which can be directly applied in the finite element analysis for RCC beam under shear load.