The Impact of Stairs on the Aseismic Properties of the Structure

Abstract

The stair is a important structural component. In current design modeling, it is cut from the entire structure as a simple beam. But stairs show serious damages in some earthquake events. It implies that the seismic capacities of stair structures could be not enough when designed as current method. To investigate the seismic behavior and the effect on the structures for the stairs, a 5-story school building is selected as a case. Two structure models are established, including and without stair. First the reinforcement inside the stairs are compared. It shows the current simple method underestimate the loadings. Second the changes in the structure are investigated when adding the stair to the structural model. The stair's participation decreases the vibration period and storey drift, and increases the structural base shear and the internal forces of the members surrounding the stair. So, it is necessary to consider the stair in analyzing models.