Weak Storied Check For Residential Building Using Etabs-2016

Abstract

The Bangladesh National Building Code (BNBC) specifies and regulates the general specifications for structural, architecture and design parameters in Bangladesh. In the last three decades, Civil Engineering techniques, knowledge, and materials as well as design parameters have been modified as per requirement. 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 behaviours 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 behaviour 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. Soft storeys in a high-rise building have a significant impact on its seismic performance. There is a discontinuity in the rigidity of the structure at the soft storey level due to a lack of infill walls or a variation in floor height. This continuity is the cause of structural failure in multi-story buildings subjected to earthquake loads