Dynamic characteristics and seismic behavior of prefabricated steel stairs in a full-scale five-story building shake table test program

This paper investigates the dynamic characteristics and seismic behavior of prefabricated steel stairs in a full-scale five-story building shake table test program. The test building was subjected to a suite of earthquake input motions and low-amplitude white noise base excitations first, while the building was isolated at its base, and subsequently while it was fixed to the shake table platen. This paper presents the modal characteristics of the stairs identified using the data recorded from white noise base excitation tests as well as the physical and measured responses of the stairs from the earthquake tests. The observed damage to the stairs is categorized into three distinct damage states and is correlated with the interstory drift demands of the building. These shake table tests highlight the seismic vulnerability of modern designed stair systems and in particular identifies as a key research need the importance of improving the deformability of flight-to-building connections.