Search

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]