Bhuj earthquake in India, 2001 had witnessed spectacular failures of a class of reinforced concrete multi-storied buildings termed as Open Ground Storey (OGS) buildings, necessitated by a functional demand to provide a parking space within a building plan. Due to the absence of brick-infilled walls at the ground floor, a sudden reduction in the storey stiffness can cause enormous seismic displacement demand in the ground storey itself. Further, the column-side sway mechanism is developed due to the presence of soft storey between the stiff upper storey and rigid base by assuming the soil support is stiff enough. The present study focuses on the effect of soil flexibility on the seismic response of open ground storey buildings. Analytical studies on typical open ground storey building models considering the soil flexibility have been carried out in SAP2000 software and static nonlinear analysis (pushover analysis) has been used to study the lateral response. Variation in boundary conditions are incorporated by simulating three different soil conditions hard, medium and soft, classified as mentioned in IS 1893 (Part 1) 2016. It is observed from the present study that the soil flexibility increases the lateral displacement and secondary forces associated with the P-Delta effect. Further, a parametric study is carried out to study the influence of soil flexibility in OGS buildings of various slenderness ratios. The importance of considering the influence of soil-structure interaction has been highlighted for obtaining a realistic performance point of the building. In addition, for preliminary and quick seismic assessment of huge stock of existing OGS buildings in Indian urban regions, a simplified methodology for estimating the lateral behaviour of a flexible base open ground storey building has been developed. This methodology is useful to segregate the highly vulnerable OGS buildings that undergo a detailed assessment prior to retrofit. The developed methodology is validated with the detailed analytical studies made on open ground storey buildings.

在2001年的印度布杰地震中，目睹了一类称为露天地面（OGS）建筑物的钢筋混凝土多层建筑的惨败，这是根据功能需求在建筑计划中提供停车位所必需的。由于底层没有砖砌墙，因此层间刚度的突然降低会导致层间本身产生巨大的地震位移需求。此外，由于假设土壤支撑足够坚硬，在刚性上层和刚性基础之间存在软层，因此开发了柱侧摇摆机构。本研究的重点是土壤柔性对露天地面建筑物地震响应的影响。在SAP2000软件中已对考虑土壤柔韧性的典型露天地面建筑模型进行了分析研究，并已使用静态非线性分析（推覆分析）来研究横向响应。边界条件的变化通过模拟3种不同的硬，中，软土壤条件而被合并，按IS 1893（第1部分）2016中所述进行分类。从本研究中观察到，土壤柔韧性增加了横向位移和与之相关的次级力P-Delta效应。此外，还进行了参数研究，研究了土壤柔韧性在各种细长比的OGS建筑物中的影响。为了获得建筑物的实际性能点，已经强调了考虑土壤与结构相互作用的影响的重要性。此外，为了对印度城市地区现有OGS建筑的大量存量进行初步和快速的地震评估，已开发出一种简化的方法来估算柔性基础露天地面建筑的侧向性能。这种方法对于隔离在改造之前经过详细评估的高度脆弱的OGS建筑物很有用。所开发的方法论已通过在露天地面建筑物上进行的详细分析研究得到验证。这种方法对于隔离在改造之前经过详细评估的高度脆弱的OGS建筑物很有用。所开发的方法论已通过在露天地面建筑物上进行的详细分析研究得到验证。这种方法对于隔离在改造之前经过详细评估的高度脆弱的OGS建筑物很有用。所开发的方法论已通过在露天地面建筑物上进行的详细分析研究得到验证。