Improving the seismic performance of staircases in building structures with a novel isolator

A staircase provides the main escape way from a building in an emergency. Unfortunately, it may suffer severe damages or even collapse during an earthquake. For improving the seismic performance of staircases, this paper proposes an innovative staircase isolator with the features of lightweight, cost-effective and ease of construction and replacement, which is formed by suitable engineering plastic shims between rubber layers. A connection construction scheme is also proposed for the isolated staircase. Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states. The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure. In order to investigate the influence of staircase on building structural responses, time history analyses of a typical building structure without staircase (WS), with fixed staircase (FS) and with isolated staircase (IS) are conducted and compared within the environment of SAP2000. Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed. When the novel isolator is employed for staircase in a building structure, there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.