The implementation of a response-oriented design, particularly the direct displacement-based design (DDBD), offers notable advantages in the era of building structures. This design paradigm revolves around determining the structural capacity to withstand earthquake loading following specific requirements. Present study includes a 15-storey reinforced concrete (RC) frame building that is meticulously modelled utilising the DDBD approach, considering fixed-based and incorporating soil–structure interaction (SSI) effects as crucial boundary conditions for life safety performance. Nonlinear p–y springs and elastic springs to capture soil nonlinearity are integrated into the design. The frames undergo thorough nonlinear static pushover analysis (NSPA) analysis to elucidate their nonlinear behaviour. Subsequent seismic fragility assessment obtained the building’s probability of occurrence in varying collapse states, ranging from slight to complete. Notably, including SSI effects in the DDBD approach yields heightened structural responses and increased design requirements with 5% lesser seismic vulnerability compared to the RC frame without considering SSI.