PSI - Issue 70

Pradhumn Agrawal et al. / Procedia Structural Integrity 70 (2025) 113–120

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1. Introduction The rapid urbanization and scarcity of flat, buildable land in hilly regions have led to the widespread development of residential and commercial structures on sloped terrains. Buildings constructed on hill slopes often adopt irregular configurations to conform to the natural topography, typically resulting in SB, set-back, or a combination of both geometries. While these configurations may be architecturally and functionally viable, they introduce significant irregularities in mass, stiffness, and load distribution, making them inherently more susceptible to seismic forces. A lot of research is being done on the structure lying on sloping ground and proof the vulnerability that the structure exhibit non-uniform dynamic responses due to the variation in column heights, floor levels, and mass eccentricities along the slope. These irregularities can lead to concentration of stresses, torsional effects, and differential displacement, particularly during strong ground motions. As a result, such buildings may experience severe damage or even collapse during seismic events if not properly analyzed and designed. Current seismic design codes and some research provide general guidelines for irregular structures, but they often lack specific provisions for hill-slope buildings with complex geometries. Therefore, a detailed investigation into the seismic behavior of such structures is essential to identify potential vulnerabilities and to develop strategies for improved seismic resilience. This study focuses on evaluating the seismic performance of a building with combined SBS configuration, resting on a typically hilly slope. Through a comprehensive structural analysis using linear static method, key parameters such as stories drift, base shear distribution, time period, and lateral displacement patterns are assessed. The findings aim to contribute to the understanding of seismic vulnerability in hill-slope and comparing the SBS configuration with only setback structure and to inform future design approaches that ensure structural safety and compliance with seismic standards. Nomenclature SB Step-back SBS Step-back Setback SSI Soil Structure Interaction 1.1 Modelling and detailing of structure G+4 residential building is taken for modelling having a plan dimension (15 m*15 m) and each storey height of 3 m, plan and 3d view of the structure are shown in Fig.1 and Fig.2. The design data for seismic analysis as per IS 1893(2016) - Zone factor= 0.36, Soil condition- Medium, Frame type=SMRF, Reduction factor=5, Importance factor=1. Properties of materials are concrete of M30 grade and Steel of FE500. Dimension of structural element, Beam having size of 250 mm* 300 mm, Column of 350 mm* 350 mm and Slab of 150 mm. The types of loads considered are dead load of beams, columns and slabs; live load =3 KN/m2 at floor level and 1.5 KN/m 2 at roof level.

Fig. 1. 3d view

Fig. 2. Plan view