Framework for Improving the Seismic Behaviour of RC MRF Buildings Resting on Hill Slopes

Abstract

In the past decade, India witnessed a surge in concentrated urban growth to manifolds. The same trend is visible in hilly regions where the seismic safety of buildings is partially answered. Also, the peak ground accelerations observed in the past earthquakes are in accordance with the design PGA, the associated damages observed are brittle, which is undesirable. This can be mainly attributed to the current design codes not providing sufficient recommendations for the safety of buildings on hill slopes. For example, the code suggests modifications to consider the height of buildings resting on slopes in calculating the lateral forces, but do not discuss the ambiguity in the shear force distribution that is inevitable at the shorter column. The parameters responsible for their ill behaviour must be well understood to improve the safety of hill buildings. Therefore, a methodology is formulated for understanding the effect of varying building dimensions on (i) design stress ratios, (ii) dynamic response, i.e., drifts, and (iii) dynamic characteristics, i.e., modal properties. Correlation matrices are plotted to identify the parameters influencing the behaviour. Further, nonlinear dynamic analysis is performed using a reference structure to detect the failure pattern. It is observed that the predominant failure is due to shear in all uphill columns, followed by the yielding of an immediate story. Based on the parameters identified, a framework is proposed to (i) restrict the shear failure in the uphill columns and (ii) improve the base shear distribution, flexural deformations, and modal properties along and across the valley. A similar nonlinear analysis is performed to confirm the improvement in the behaviour of buildings resting on slopes