DYNAMIC CHARACTERISTICS ASSESSMENT OF STEEL BEAM-COLUMN CONNECTIONS WITH FLOOR SLAB

The dynamic characteristics of steel buildings and their structural components change with damages induced by severe earthquake loading, while the amount of changes vary with the severity of damage. Nevertheless, the identification of the exact sources of the changes is challenging because the observed changes are not drastic due to the redundancy in building structural systems. Moreover, the combination of various types of structural damage, softening in foundation, and composite actions of different structural materials complicate the identification process of damage. Accordingly, this research examines the influence of different structural damages on the dynamic characteristics of a beam-column connection with concrete floor slab. A full-scale specimen was incrementally damaged with quasi-static cyclic loading and forcedvibration test was conducted at the occurrence of notable damage. In the test, the influences of different type of damages, i.e. crack in floor slab, beam local buckling and beam-end fracture, on the natural frequencies of the specimen were carefully monitored. Test results showed the large influence of floor slab cracking and relatively small influence of beam-end fracture on the natural frequencies when the specimen was locally excited with the source of excitations near the connection. This finding was further examined analytically and numerically.