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In order to study the seismic performance of the staircase in the cast-in-place reinforced concrete frame, a 1/2 scaled specimen of the structural unit composed of concrete frame and staircase was tested quasi-statically. The test demonstrated the failure mode and mechanism of the structural unit as a whole and those of its various components, and the load-carrying capacity, displacements and other aspects related to seismic behavior were also measured. The test shows that, when fully connected to the main structure with the conventional manner of construction, the staircase works as asymmetrically inclined bracings in the structure, resulting in its early cracking and fast damaging, and consequently, its functions, such as seismic rescue and evacuation, could not be ensured; meanwhile, it also causes irregular forces of the frame members, leading to the brittle failure of the column in one side of frame and then the complete failure of the specimen. The enclosed area of hysteretic loop of the specimen is relatively small and its peak value of load reaches high but, after that, the capacity decreases fast. The rigid connection between the frame column and the supporting beam of the stair platform on the half story makes some frame columns, which are already in complex state of loading, the short columns, leading to the local collapse of such column and failure in other parts of the frame suddenly. Therefore, the staircase connected to the concrete frame with such a conventional manner as mentioned above is adverse to seismic resistance of the structure. [ABSTRACT FROM AUTHOR]

A new measure, in which sliding supports are used between the staircases and the main structure, is proposed in the current code for seismic design of buildings. To experimentally verify the new measure, the shaking table test of a large scaled structural unit of concrete frame-staircase with sliding supports made of ploytetrafluoroethene ( PTFE ) plate was conducted to dynamically test its performance under input motions of different intensities. It shows that, with the sliding supports at the lower end of the stairway slabs, the seismic behavior of the structural unit of concrete frame-staircase is satisfactory; even subjected to very severe motions, serious damages happen mainly in the members of concrete frame and no serious failure occurs earlier than the frame in the staircase parts, including stairway slabs, platform, supporting beams and columns; the sliding support made of PTFE plate works effectively and, horizontally along the direction of the input motions, the lower ends of the stairway slabs can slide back and forth as expected; meanwhile, they also have repeated up and down movements there. [ABSTRACT FROM AUTHOR]