Experimental Investigation On Seismic Performance Of High Strength Bars Reinforced Concrete Shear Walls With External MRD

Shear walls are often used as the key components of high-rise or super-high-rise structures and are widely used in areas with frequent earthquakes because of the high vertical bearing capacity and high lateral stiffness.The normal reinforced concrete shear wall structures are damaged seriously after the earthquake,which brings serious influence to the normal use and reinforcement of the structure after the earthquake.With the improvement of seismic design requirements of buildings and the development of seismic design theory,the seismic technology of structures presents the development trend from seismic and damping to recoverable functional structures,so that the structure has the ability to quickly restore the function after the earthquake,while ensuring the safety of life,but also to reduce the impact of functional deterioration due to structural earthquake.In this paper,high strength bars reinforced concrete shear walls with CFRP bars or steel strand in the edge members are designed,and the energy dissipation elements — magnetorheological damper(MRD)are configured on the walls.The pseudo-static tests of 1 CFRP bars reinforced concrete shear wall with a height-width ratio of 2.0,1 CFRP bars reinforced concrete shear wall of external MRD with a height-width ratio of 2.0 and an external MRD steel strand-reinforced concrete shear wall with aspect ratio were completed under the axial pressure ratio of 0.26.Based on the analysis of the failure form,hysteresis characteristics,skeleton curve,displacement ductility,residual deformation and energy dissipation ability of 3 shear wall specimens,the influence of longitudinal reinforcement type of edge members and peripheral MRD on the seismic performance and self-reset performance of shear wall are discussed.The test results show that:(1)Different high-strength reinforcement(CFRP bars or steel strand)or peripheral MRD in the shear wall edge members will change the distribution pattern of wall cracks;The steel strand wire of peripheral MRD reinforced concrete shear wall has the highest crack development height,and the crack area accounts for 90%of the wall height,and the maximum crack width is the smallest,no more than0.8mm.(2)Three types of shear wall specimens have a high bearing capacity,which reflects the effect of high tensile strength of CFRP bars and steel strand;The limit interlayer displacement angle of steel strand reinforced concrete shear wall is 1/57,and is 0.88 times that of CFRP reinforced concrete shear wall,which is greater than1/120 of the limit value of elastic-plastic interlayer displacement angle specified in technical specifications for concrete structures of high-rise buildings.(3)The maximum pre-loading stiffness of the wall can be increased by 28.3%by placing an external MRD on the wall;The bearing capacity degradation coefficient of all specimens is kept between 0.9 and 1.0,which indicats that the shear walls with longitudinal CFRP bars or steel strand in the edge members have better bearing capacity stability under repeated loads.(4)The stiffness of the steel strand-reinforced concrete shear wall with external MRD is larger,the lateral limit deformation is smaller and the corresponding energy dissipation capacity is lower;The external MRD makes the wall enter the plastic yield stage in advance and increases the displacement ductility.The corresponding single-cycle energy consumption and cumulative energy consumption are both improved,and the cumulative energy consumption increment at the end of loading reaches 18.1%.(5)The maximum crack width of the three specimens under loading is no more than 1.6mm,the residual crack width after unloading is no more than 0.6mm,and the corresponding residual deformation is within 12 mm,indicating that the shear walls designed in this paper still have good self-resetting performance under large deformation.