[20] INVESTIGATION OF COLUMN SHEAR DEMAND IN OPEN GROUND STOREY STRUCTURES SUBJECTED TO EARTHQUAKE LOADS

ARTICLE INFO- Date of Submission: Sep 10, 2024, Revised: Sep 24, 2024, Accepted: Sep 27, 2024, CrossRef d.o.i.: https://doi.org/10.56815/IJMRR.V3I3.2024/193-214, How to Cite: H S Vishwanatha & Sreekeshava K S (2024). Investigation of Column Shear Demand in Open Ground Storey Structures Subjected to Earthquake Loads. International Journal of Multidisciplinary Research & Reviews. 3(3). 193-214.

Abstract

Open Ground Storey (OGS) buildings are known to be highly susceptible to seismic damage due to the development of a soft storey at the ground level, which leads to a considerable reduction in lateral stiffness and a corresponding increase in shear demand on columns. This research investigates the distribution of shear forces in columns of three-dimensional (3D) reinforced concrete (RC) OGS frames subjected to earthquake loading. The study primarily evaluates the performance of two lateral load-resisting systems (LLRS), namely the provision of strengthened ground floor columns and the incorporation of shear walls arranged in different configurations. A comparative assessment is carried out between conventional OGS frames, bare frames, and infilled frames to understand the influence of masonry infill on seismic response. The analysis indicates that the presence of infill walls considerably enhances structural stiffness, resulting in a significant reduction in column shear forces—up to approximately 70% when compared to bare frame conditions. In contrast, OGS configurations without infill at the ground level exhibit an increase in shear forces of nearly 78% in ground floor columns relative to fully infilled frames, highlighting the adverse effect of stiffness discontinuity. The introduction of shear walls in OGS structures proves to be an effective strategy in mitigating these increased shear demands. The ratio of shear force in ground floor columns to that in the first floor, which ranges between 6.25 and 8.60 in typical OGS models, is substantially reduced to values between 0.52 and 5.74 when shear walls are incorporated. Additionally, it is observed that peripheral and corner columns experience approximately 10% higher shear forces compared to interior columns, indicating the need for careful design considerations in these critical locations. The study further reveals that an increase in ground floor height by 1meter leads to an approximate 25% rise in shear forces in the ground storey columns, emphasizing the influence of geometric parameters on seismic behavior. Overall, the findings highlight the necessity of appropriate structural interventions, such as optimal shear wall placement and enhanced column design, to improve the seismic performance and safety of OGS buildings.