Experimental investigation on seismic behavior of steel welded connections considering the influence of structural forms

Abstract

The traditional welded connections of steel moment frames are prone to brittle fracture in earthquakes due to the high stress concentration at the beam end, which significantly affects the seismic performance of steel frame structures. A novel type of steel connection with local structural forms is proposed to avoid brittle fracture. The proposed connection is developed by both of cover plate strengthened at the beam flange and the opening weakened at the beam web. The quasi-static tests of 8 welded steel connections were carried out to investigate and validate the proposed connection. The failure mode, hysteretic behavior, strength and cyclic degradation behavior, ductility and rotation behavior, stiffness behavior, and energy dissipation behavior of 8 connections were analyzed and further discussed. Moreover, the effects of different local structural forms, such as length of cover plate and diameter of web opening, on the proposed connection were experimentally investigated in detail. Also, the seismic performance of the proposed connection was comprehensively compared with the traditional connection. The results show that the proposed connection can achieve the plastic hinge away from the face of the column, thereby avoiding the brittle failure at the beam end, exhibiting excellent seismic performance. The comparisons demonstrate that the proposed connection presents a satisfactory ductility and plastic rotation behavior. A good cumulative plastic rotation and cumulative energy consumption can be observed in the proposed connection. However, the traditional connection shows a poor energy dissipation behavior. In addition, the strength and stiffness behavior of the proposed connection are not much different from the traditional connection, but the hysteretic, ductility, plastic rotation, and energy dissipation behavior can be considerably improved. The results confirm that the proposed connection is verified for seismic behavior and can be considered as a reasonable steel welded connection. Consequently, the proposed connection can be recommended to be directly adopted in the beam-to-column connection for steel frame structures under seismic design.