Experimental Study On The Seismic Resistance Performance Of Steel Fiber Reinforced High-strength Concrete Frame Exterior Joints

In this paper, through the low-cycle reversed loading experiment on 9 specimens of high-strength concrete frame exterior joint -7 specimens among them are steel fiber reinforced high-strength concrete frame exterior joints, the influence of the relevant factors which are the volume ratio of steel fiber, the axial compression ratio and the addition range of steel fiber etc on the seismic ductility, structural deformation and energy dissipation capacity of steel fiber high-strength concrete frame exterior joint is investigated, and the relevant experimental parameter value which is beneficial to seismic resistance performance of frame exterior joint is proposed. The main contents are as follows:(1) The chosen volume ratios of steel fiber are respectively among 0.5%, 1.0% and 1.5% to study the influence of steel fiber on the frame exterior joint.(2) The chosen axial compression ratio are respectively among 0.2, 0.3 and 0.4 to study the effect of the axial force at the end of column on the seismic performance of steel fiber reinforced high-strength concrete frame exterior joints and the deformation performance of joint core.(3) The chosen addition range of steel fiber are respectively among 80mm, 125mm and 250mm to study the effect of the addition range of steel fiber on the ductility performance of steel fiber reinforced high-strength concrete frame exterior joint.(4) To compare conveniently with the ductility performance of steel fiber reinforced high-strength concrete frame joint, one high-strength concrete frame joint specimen is designed by relative regulations in 9 specimens of high-strength concrete frame exterior joint.The experiment shows that steel fiber can improve the seismic resistance performance of high-strength frame exterior joint, and control the place of beam cracks. The results include the following:(1) All indexes of seismic resistance of frame joint have improvement in varying degrees with the volume ratio of steel fiber increasing.(2) When the volume ratio of steel fiber is 1.5%, the specimen without core stirrups can satisfy the seismic demands. Compared with the specimen designed by relative regulations, the addition of steel fiber improves of the section ductility of beam plastic hinge zone, shear deformation of joint core, displacement ductility of structure and energy dissipation capacity. (3) With the increasing of axial force at the end of column, the energy dissipation ability of joint core is increased. However, when the cracks of core concrete appear, the higher axial force accelerates the development of cracks and the damage of core.(4) The addition range of steel fiber should not be too large, and be controlled in the range of one beam height.