Mechanical Performance Analysis and Construction Techniques of Prefabricated Damped Staircases

Targeting the issue that conventional staircases in prefabricated buildings are prone to premature damage under seismic actions, thereby impairing the overall seismic performance of the structure and compromising evacuation safety, this study proposes a new type of prefabricated damped staircase system together with its corresponding construction procedure, suitable for practical engineering applications. Based on a representative prefabricated building project, a comparative numerical analysis was conducted between a conventional cast-in-place staircase and the proposed prefabricated damped staircase, and key detailing measures as well as installation techniques were summarized in conjunction with engineering practice. The results indicate that the prefabricated damped staircase exhibits a low-stiffness initial stage governed by the rubber bearings prior to the elastic stage, with an initial deformation capacity of approximately 80 mm, which significantly delays the onset of damage in the flight slab and platform beams. The ultimate displacement of the conventional cast-in-place staircase is about 41.87  mm, lower than the 49.14  mm corresponding to a story drift ratio of 1/50, whereas the damped staircase still possesses sufficient deformation margin after reaching a story drift ratio of 1/50, thereby markedly enhancing the deformation capacity and safety reserve of the staircase substructure. In terms of failure mode, the conventional cast-in-place staircase experiences tensile cracking and premature failure at relatively small story drifts, while the damped staircase exhibits almost no significant tensile damage within a horizontal displacement of 80  mm and attains a peak load noticeably higher than that of the cast-in-place counterpart. These findings demonstrate that the proposed prefabricated damped staircase system outperforms traditional cast-in-place staircases in load-bearing capacity and deformation capacity, and thus holds considerable promise for practical engineering applications.