Seismic Pounding Effects of Typical Midrise Reinforced Concrete Structures Subjected to Soil–Structure Interaction Effects

In densely populated urban areas, construction spaces are often limited, resulting in insufficient separation between adjacent structures. This issue is compounded by soil–structure interaction (SSI), which significantly alters the dynamic response of buildings. Inadequate separation gaps can lead to increased seismic forces and interstory drift ratios (IDRs), potentially causing significant structural damage and resulting in the loss of life and property. Using inelastic time-history analyses with scaled ground motion records, this research investigated the rapid calculation of seismic gaps between adjacent structures, as well as the impact of SSI on seismic pounding forces and IDRs across different soil conditions, with comparisons made via fixed base. Nonlinear models of 8- and 10-story reinforced concrete (RC) structures, representative of the Turkish building stock, were analyzed in both standalone and adjacent scenarios. Ground motion records were scaled to match the seismic characteristics of Istanbul, a highly earthquake-prone region, and nonlinear time-history analyses were conducted in both horizontal directions simultaneously. This study primarily examined two scenarios. The first scenario involved a rapid assessment based on building height and soil conditions, which can be utilized during the design phase to prevent pounding between adjacent buildings and compared with gap separations calculated using more-complex formulas recommended by regulations. The second scenario addressed the additional shear forces resulting from pounding effects, which must be considered if pounding cannot be avoided. This study proposes a simplified method for determining seismic gaps, aiding practical application for field engineers. This study found that simultaneously considering both SSI and pounding significantly alters dynamic behavior in terms of maximum IDRs and acceleration demands, especially in shorter and lighter structures.