Study of stainless steel bolted extended end-plate joints under seismic loading

Abstract

Bolted stiffened extended end-plate (BSEP) joint is a commonly used beam-to-column joint in steel frames. In this paper, five full-scale stainless steel BSEP joints were tested under cyclic loading. The tested joints were made of Grade S31608 (EN 1.4401) stainless steel welded I-sections, assembled by four types of bolts, including galvanized high strength bolts of Grades 10.9 and 8.8, and austenitic stainless steel bolts of Grade A4-70 and A4-80. Variations of end-plates of different thicknesses (16 mm and 20 mm) were also considered in the design of the test specimens. Material properties of the plates were tested and the slip-resistant behaviour of the bolts with surface treatments were obtained prior to the joint tests. The test setup, loading protocol and instrumentation employed in the tests are described herein. The obtained test results are reported, including the full moment-rotation curves and the failure modes of the joints. It is observed from the seismic tests that hysteresis curves of all specimens show some sliding and pinching, especially for connections with stainless steel bolts or thin end-plates. The test results were used to validate finite element (FE) models, which can be employed for further numerical investigations. The test results were also employed to assess the stiffness and moment resistance capacity predictions according to the current European design provisions.