Seismic Behavior Research On The Damage Controllable Column Base Based On Resilient Disaster Prevention

Exposed column base are widely used in medium and low-rise steel structures.However,it was observed by the post-earthquake field investigation that not a few buildings collapsed were severely damaged due to the fracture of anchor bolts.In addition,the behavior of column base is characterized by severely pinched hysteresis that has low capacity of energy dissipation.Once the column base is fractured,it is difficult to repair it rapidly after the earthquake.In order to solve the shortcomings of the exposed column base,based on the "resilient" disaster prevention design requirements,this paper designs three new kind of column base: double yield mechanism column base,replaceable column base and customizable column base.The double yield mechanism is achieved by using two layers of base plate.Two yield mechanism are the base plate yield mechanism and anchor rods yield mechanism.The test parameters were the inner anchor rods and the outer base plate.Four specimens were tested to investigate the seismic behavior of the double yield mechanism column base.It is noted that the behavior of the double yield mechanism column base can be decomposed into that of anchor rod yield column base and base plate yield column base.The moment resistance and the energy dissipation capacity of exposed column base connections are increased significantly.Under large deformation,it is controlled by base plate yield mechanism due to the fracture of the inner anchor rod.The double yield mechanism column base could avoid sudden damage because of the high ductility of the outer base plate.The thickness of the outer base plate is the key factor to determine the behavior of the double yield mechanism column base.It is suggested that the moment resistance and the energy dissipation capacity of the double yield mechanism column base can be improved by increasing the outer base plate thickness.Based on the test results,the distribution characteristics of the yield line of the double yield mechanism are proposed,and mechanical behavior and the calculation method of moment resistance are given based on the virtual work principle.The replaceable plate is placed on the replaceable column base so that the deformation and energy consumption of the replaceable column base are mainly concentrated on the replaceable plate during the earthquake.The replaceable plate is fractured after the earthquake and can be replaced rapidly to achieve the energy dissipation and the goal of rapid repair after the earthquake.The experimental study on the proposed replaceable column base shows that the replaceable column base can effectively improve the energy dissipation.When the column top drift is 3%,the energy consumption is twice that of a conventional exposed column.Based on the results,the formation characteristics of the plastic hinge of the replaceable plate are analyzed.The mechanical behavior and the calculation method of moment resistance are proposed.The customizable column base are equipped with dampers on both sides of the steel column to improve the energy consumption and seismic performance of the column base.There are three kinds of dampers equipped with the customizable column base: tension and compression damper,shear damper and support damper.The mechanism behavior and design method of the customizable column base are theoretically analyzed.Based on this,the finite element model is created by ABAQUS to investigate the hysteretic behavior of the column base under cyclic loading.The validity of theoretical analysis is verified by the FEM results.Finally,the effect of the axial compression ratio and width-thickness ratio on the tension and compression column base are studied by the numerical model and the design suggestions are proposed.