Seismic Assessment of Multistorey building of plan irregularity with varying A/L ratio (Re-entrants corners)

Buildings with re-entrant corners are used when maximum utilization is done over minimum available space. These re-entrant corners come under the plan irregularities of the structures. Plan irregularity (or) Vertical irregularity makes vulnerable under seismic loading. Structural irregularities are an important factor in that structure’s seismic performance structure. This study aims to gain the seismic behaviour of the building with an L-shape floor plan by checking the irregularity of re-entrant corners by seismic response demands that is been measured with varying A/L ratios. The response includes top floor displacement, interstory drift, Story Stiffness, and base shear. The study consists of 5 models with varying A/L ratios with 3 sub-divided models of various seismic positions of the shear wall (i.e.) a model without a shear wall, a model with a shear wall at the centre, a model with a shear wall at the periphery. 15 models are made for a clear study of the seismic behaviour and the effective position of the shear wall with varying A/L ratios. The models are analysed with ETABS using the Equivalent static method (ESL) and Response Spectrum (RS) methods. The results prove that the model with a lesser A/L ratio satisfies the analysis even without the shear wall excluding the lift RCC wall, whereas when the A/L ratio increases the model is effective only when the shear wall is provided at the periphery. Thus, the economical and effective seismic position of the shear wall is found with varying A/L ratios and satisfies the seismic demand for the structure. As the building with re-entrant corners are more vulnerable the building plan must be of regular configuration to possess significant seismic resistance.

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