Performance evaluation of setback buildings with open ground storey on plain and sloping ground under earthquake loadings and mitigation of failure

Rahul Ghosh,Rama Debbarma

doi:10.1007/s40091-017-0151-3

Abstract

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures also have stiffness irregularity in elevation. The risk factor of such structure may increase, if the structure rests on sloping ground. In this paper, an attempt has been made to evaluate the seismic performance of setback structures resting on plain ground as well as in the slope of a hill, with soft storey configuration. The analysis has been performed in three individual methods, equivalent static force method, response spectrum method and time history method and extreme responses have been recorded for open ground storeyed setback building. To mitigate this soft storey effect and the extreme responses, three individual mitigation techniques have been adopted and the best solution among these three techniques is presented.

Highlights

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures have stiffness irregularity in elevation
The analysis has been performed in three individual methods, equivalent static force method, response spectrum method and time history method and extreme responses have been recorded for open ground storeyed setback building
The effect of soft storey configuration on the setback building resting on slope is studied along with their collapse prevention techniques

Summary

Introduction

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures have stiffness irregularity in elevation. Ghosh and Debbarma (2015) investigated the deficiency of soft storeyed structure in both linear static and linear dynamic method They recommended the use of shear walls in the soft storey to mitigate its failure by increasing its stiffness and controlling its displacement and drift excellently. storied sloped frame building having step back–set back configuration for sinusoidal ground motion with different slope angles by performing response spectrum analysis They observed that short column was affected more during the earthquake. storey RCC building on varying slope angles and compared with the same on the flat ground using linear static method They observed that the footing columns of shorter height attract more forces, because of a considerable increase in their stiffness, which in turn increased the shear and bending moment significantly. All the details related to structure, which are taken as per Ghosh and Debbarma (2016), are provided here

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Conclusion