Effect Of Secondary Forces Induced By Buckling-restrained Braces On Failure Modes Of RC Frame Columns Under Severe Earthquake

As an energy-consuming device,the buckling-resisting bracing(BRB)not only solves the compressive buckling problem of ordinary structural supports under the action of large earthquakes,but also exerts the good plastic deformation ability of steel,which can obviously reduce the main body of the building.The degree of damage of structural members under the action of large earthquakes.However,under the action of a large earthquake,the anti-buckling bracing may be damaged before the beams and columns of the reinforced concrete frame structure,so that the anti-buckling bracing lacks the energy dissipation and shock absorption effect on the reinforced concrete frame structure,and finally makes the anti-buckling bracing and other components unable to The main reason for effectively achieving the expected seismic target is that in the current seismic engineering design of reinforced concrete frame structures,the inter-connection of buckling bracing,gusset plate and sub-frame is designed as a relatively independent structural system.The strong effects of the above three between adjacent components are ignored.In this paper,based on the fact that the additional force of the antibuckling bracing under the action of a large earthquake causes the RC sub-frame structural support to be in a relatively complex stress state,the study on the influence mechanism of the additional force of the anti-buckling bracing on the failure mode of the RC frame column under the action of a large earthquake is carried out.The main research contents and conclusions of this paper are as follows:(1)The second chapter analyzes the stress state of the frame structure of the bucklingresistant braced RC,establishes the beam-column assembly finite element model based on the ABAQUS analysis software,and uses the beam-column assembly quasi-static test completed by the research group to verify.The analysis results show that under the action of a large earthquake,the beam-column of the RC sub-frame will bear the additional axial force of the anti-buckling bracing,the additional bending moment and the opening and closing of the gusset plate,resulting in a complex stress state;the beam-column assembly is damaged.The simulation analysis results of seismic performance such as mode,plastic hinge transfer and hysteretic performance are in good agreement with the quasi-static test results,which verifies the validity of the established finite element model of the buckling-resistant braced beamcolumn assembly.(2)The third chapter studies the plastic hinge transfer of the structure through three groups of buckling-resisting braced RC frame structures with different connection methods.The effect of plastic hinge transfer.The analysis results show that the shear strength between the gusset plate and the column has a very important influence on the transfer of the plastic hinge.Specifically,the plastic hinge is transferred by enhancing the flexural bearing capacity in the gusset plate region through different connection methods.When the bending strength of the gusset plate area exceeds the bending moment,the plastic hinge will be transferred to the place outside the gusset plate.At the same time,the position of the resultant force point of the gusset plate is analyzed,and it is concluded that the position of the resultant force point under different connection methods and different parameters is not fixed.At the position of 0.6 times of the gusset plate,but with the increase of the flexural bearing capacity,the position of the resultant force of the gusset plate is gradually shifted from the position of 0.4 times of the gusset plate to the position of 0.6 times of the gusset plate.(3)The fourth chapter analyzes the shear resistance of the buckling-braced RC frame column D zone through four groups of traditional stud connection methods with different parameters.Effect of axial compression ratio and concrete strength at high and low axial compression ratios on shear resistance of monolithic columns.The result analysis shows that increasing the strength and diameter of the stirrups in the D zone can effectively ensure that the column D zone does not suffer from shear damage and ensure the energy dissipation capacity of the anti-buckling brace;the change of concrete strength has a basic effect on the shear resistance capacity of the D zone There is not much effect;under the high axial compression ratio,the structure will cause small eccentric failure of the whole column due to the combined effect of the axial force,the normal component of the anti-buckling support and the normal component of the opening and closing effect;the concrete strength under high axial compression ratio The improvement of the grade can also effectively improve the shear resistance of the beam-column specimen.Finally,the influence mechanism of the additional force of the anti-buckling bracing on the column failure mode of the beam-column assembly is expounded.