Abstract

In the conventional design of steel structure joint,the steel frame joint will achieve energy consumption through yield and plastic deformation under earthquake loads.This sacrificial design approach can lead to permanent,and often irreparable damage when interstory drifts are too large.A new kind of steel frame joint is proposed.By the superelasticity of shape memory alloy(SMA)[1],it can achieve damage avoiding and recentering capabilities[2].In this new type of steel frame joint(Figure 1)using SMA,the beam and column are connected by steel angle and bolts on the upper flange of the beam.

Figure 1　Recentering steel frame joint in ABAQUS

The buckling-restrained SMA member is located at the lower side of the beam,and is connected with the lower flange of the beam with steel angle and bolts.When the lateral displacement occurs,the rotation between the beam and the column around the upper steel angle occurs[3],and the bucklingrestrained[4]SMA member deforms to achieve energy consumption.ABAQUS is used to simulate the buckling-restrained SMA member and the recentering steel frame joints.Simulation of the bucklingrestrained SMA shows that when the inner core of SMA is subjected to the cyclic displacement loads,the external restraint sleeve restricts the buckling deformation of the inner core of SMA,and the buckling-restrained SMA member shows a stable flag-shape hysteretic curve(Figure 2),which preliminarily verifies the feasibility of the buckling-restrained SMA members.

Figure 2　The flag-shape hysteretic curve of the buckling-restrained SMA member

Simulating results of the recentering steel frame joints indicate that the moment-rotation curve of the joint is obtained to verify the recentering performance of the joint.Therefore,this kind of steel frame joint can achieve recentering and energy dissipation without damage,in contrast to conventional sacrificial design.