Seismic performance of Reinforced Concrete Buildings with openings in URM Infill walls: A Soil-Foundation-Structure Modelling approach

Amritha Nath¹Prasanth S^2*

• ¹School of Civil Enginnering, Vellore Institute of Technology, Vellore, India
• ²Centre for Disaster Mitigation & Management (CDMM), Vellore Institute of Technology, Vellore, India

This study aims to capture the impact of soil-structure interaction on infill openings in Unreinforced Masonry infilled Mid-rise and High-rise Reinforced Concrete (RC) buildings. The Soil-Foundation-Structure modelling method was adopted to incorporate the soil-structure interaction effect using the finite element software PLAXIS 3D. A six-storey and eleven storey RC building with varying infill opening percentages of 20%, 30%, and 40% were considered to resemble realistic door/window openings. Both building models were subjected to dynamic analysis under bidirectional loading considering soft and stiff soil conditions. Maximum roof displacement, Inter-Storey Drift Ratio, mode shapes, damage state level were set as the performance assessment parameters. It was observed that the inter-storey drift ratio has increased significantly for all the models under soft soil condition especially in case of 40% infill opening. HAZUS methodology was used for assessing the damage state level at each storey level. The mid and high-rise building reaches maximum of moderate and moderate extensive damage state level respectively at 30 % infill opening cases under both soil conditions. Fixed base conditions consistently underestimated the storey damage state level. Based on performance assessment parameters, the optimum infill opening of 40% was estimated for mid-rise and 30% was estimated for high-rise building respectively under stiff soil conditions. However, these optimal percentages significantly got reduced to 30% and 20% respectively in case of soft soil condition. The findings indicates that the soil conditions and height of the building have a significant impact in infill openings percentage which affects the seismic performance of the building. This study concludes that soil-foundation-structure modelling is important for accurate seismic assessment, particularly in high seismic prone areas.