Failure of weak-storey during earthquakes

The base floors of the existing buildings are generally arranged as garages or offices. No walls are built in at these floors due to its prescribed usage and comfort problems. But upper floors do have walls separating rooms from each other for the residential usage. In these arrangements, the upper floors of most buildings are more rigid than their base floors. As a result, the seismic behaviors of the base and the upper floors are significantly different from each other. This phenomenon is called as the weak-storey irregularity. Weak stories are subjected to larger lateral loads during earthquakes and under lateral loads their lateral deformations are greater than those of other floors so the design of structural members of weak stories is critical and it should be different from the upper floors.In this paper; the seismic behavior of weak-storey is studied. Calculations are carried out for the building models which are consisting of various stories, storey heights and spans. Some weak-storey models are structural systems of existing buildings which are damaged during earthquakes. The results are compared with the current earthquake code. The ratio of buildings which have weak-storey irregularity is determined for both Ankara and Eskisehir regions. It is observed that negative effects of this irregularity can be reduced by some precautions during the construction stage. Also some recommendations are presented for the existing buildings with weak-storey irregularity.