EXPERIMENTAL WORK ON DUCTILE END-DIAPHRAGMS FOR SLAB-ON-GIRDER STEEL BRIDGES

Ductile end-diaphragms have been recently proposed as a seismic retrofit strategy to protect the substructures of existing steel slab-on-girder bridges from damage during earthquakes. This paper presents the results from an experimental work to investigate the adequacy of some proposed details. Cyclic tests on full size girder specimens having the proposed ductile diaphragms demonstrate their adequate initial elastic stiffness, strength and capacity to dissipate hysteretic energy in the intended manner. The specimens developed a rotational capacity of ۰.۲ rad when Triangular plates Added Damping And Stiffness (TADAS) energy dissipation devices were used and link distortion angles of ۰.۰۸ to ۰.۱] rad when Eccentrically Braced Frame (EBF) and Shear Panel Systems (SPS) were in place, corresponding to average ductilities of ۸ to ۱۰ before failure. However, specimens without any diaphragm dissipated significantly less hysteretic energy, and suffered buckling of the web stiffeners and fracture of the stiffeners welds at large drifts.