The Mechanical Performance Analysis Of A Slip Semi-rigid Column Base And Its Application

In the development of the modern structural system,steel structure occupies a decisive position.In the high-rise steel frame structure,the node connection is an important part of the structural system.The connection between components is usually considered to be completely rigid or hinged.This assumption simplifies work,but virtually any type of connection is a semi-rigid connection between a gang connection and a hinge connection.The column base as the superstructure and the basis of the connection site,has important research value.The column base model proposed in this paper uses elliptical sliding holes and high strength bolts to connect the column base and use friction slippage between the bottom plates and between the bottom plates and the foundation to carry out the energy-consuming semi-rigid joints.Under the action of vertical axial force and bolt pre-tightening force,the column base will slip when the shear force is larger than the static friction force required for the sliding of the column base.Through the simplified calculation of the model,the shear-slip curve and the Moment-rotation curve of the joints are studied theoretically.The shear-slip curve and the Moment-rotation curve of the joint are obtained by using the finite element software ANSYS to carry out the unidirectional horizontal displacement loading,and the results are compared with the theoretical analysis.The influence of different axial compression ratio and friction coefficient on the two curves is also analyzed.The greater the axial compression ratio,the greater the friction resistance,and the more difficult the model is to slide.The shear strength and shear stiffness of the model increase with the increase of the friction coefficient,and the closer the column base joint is to the rigid connection.The Shear-slip curve and the Moment-rotation curve are compared with the corresponding single-base column base model.Under the action of horizontal reciprocating cyclic load,the shear-slip hysteretic curve corresponding to the single and double baseplate semi-rigid column base model can be obtained,and the energy dissipation performance of the two kinds of column base is compared and analyzed.When the displacement load is the same,the slip displacement generated by the single-layer bottom column base model is smaller than that of the double-layer bottom column base model,and the more shear force is needed to generate the same slip amount of the single-layer bottom column base model.The relationship between shear hysteresis performance and friction coefficient was analyzed.By contrast,to some extent,the friction coefficient is too large for the slip of the column base,and the semi-rigid characteristic is not obvious.Three plane frame models are established,each of which is two-story and two-span,one is rigidly connected,the other two are semi-rigid connections,and one frame is semi-rigid connection of double-layer bottom plate.The other frame is a semi-rigid connection with a single floor plate.The shear-slip hysteretic curves of three frames under reciprocating cyclic displacement load are drawn respectively.It can be found that the hysteretic curve of semi-rigid frame with double floor column base joint is high,which indicates that the hysteretic energy dissipation performance of semi-rigid frame with double baseplate column base joint is obviously better than that of semi-rigid frame and rigid frame with single-layer bottom column base joint.It is more favorable to the earthquake resistance of the structure.