Magnification required by open ground storey column to mitigate stiffness deficiency of reinforced concrete structures under earthquake excitation

Open ground storey (OGS) structures are unquestionably in demand due to the functional advantages associated with such structures. The lack of stiffness provided by infill walls in the ground storey (GS) level leads to severe damage to the whole structure. There are various techniques to make OGS structures safe by improving OGS stiffness. However, most of these are either difficult to implement, reduce the functional efficiency of OGS structures or become uneconomical. The easiest recommended technique is to magnify the OGS columns by a predefined magnification factor (MF) which is noted to be insufficient in many situations to mitigate stiffness deficiency and needs several iterations to obtain appropriate MF. The process of determining MF iteratively requires significant effort and computational involvement. This, makes it difficult for professionals in routine uses. Therefore, it seems to be important to obtain the MF generically and in a simplified manner to readily obtain the MF to satisfy the stiffness demands of OGS so that the magnified OGS columns can effectively mitigate the stiffness deficiency of OGS structures. In the present study, a simplified relation is proposed based on regression analysis to obtain the MF to satisfy the stiffness demands of OGS columns. The computed MFs are observed to be sufficient enough to improve the stiffness percentage of OGS structures to avoid soft storey problems. The accuracy of the proposed empirical relation is validated with different configurations of structural parameters and the results are found to be in good agreement.