Research on Seismic Performance of Frame Structure with Beam Staircases

Beam staircases are widely used in frame structures. In structural design, stair flights are often ignored in the model establishment, and their loads are only added to the stair beams. However, under a seismic load, the flight of stairs will increase the staircase’s stiffness and affect the seismic response characteristics of the stairs and even of the structure. According to the engineering example, the finite element numerical models of the pure frame structure without staircases, the frame structure with fixed connection beam staircases, and the frame structure with sliding connection beam staircases were established. Modal analysis, response spectrum analysis, and elastic time-history analysis were carried out. By comparing the maximum story displacement, story displacement angle, natural period, story shear force, and the internal force of components of each model, the influences of beam staircases and their bearing connection mode on the seismic performance of the building were analyzed. In addition, by examining the frame model with sliding connection beam stairs, the influences of different staircase positions on the seismic performance of the building were studied. Finally, the advantages and disadvantages of different design schemes were compared, and the effects of the modeling method, support type, and layout position of the beam staircases on the seismic performance of the frame structure were summarized. The conclusions are that the story drift angle of the sliding connection structure is larger than that of the fixed connection structure, and the internal force of the frame columns of the former is smaller than that of the latter. Moreover, the positions of the staircase will affect the horizontal displacement of the structure.

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