Modeling of semi-rigid beam-to-column steel joints under extreme loading

Joints play an important role in providing ductility for steel-composite structures subject to extreme loading conditions,such as blast,fire and impact.Due to sound energy dissipation capability and fabrication efficiency,semi-rigid joints have increasingly received attention during the last decade.This paper presents a component approach for modeling semi-rigid beam-to-column joints based on Eurocode3,where the post-elastic response,including component strain hardening and ultimate rotational capacity,is also considered.Failure criteria are defined based on the ultimate deformation capacity of components and bolt-rows.The model enables a direct integration of joint response into global frame models with the consideration of axial deformability,such that the interaction between bending moment and axial force within the joints can be realistically captured.In addition,elevated temperature can be considered in the joint model via the degradation of the component response.Through comparisons with available test data,the joint model is shown to have good accuracy,and the failure criteria are found to be reliable yet conservative.The strain hardening response of components is shown to have significant influence on the ultimate bending capacity of the joints,while neglecting it usually leads to a conservative prediction.