Fast Nonlinear Analysis (FNA) for the Seismic Performance Assessment of Existing Reinforced Concrete Prefabricated Residential Buildings

Existing reinforced concrete prefabricated residential buildings constructed before the introduction of modern seismic design provisions constitute a significant portion of the building stock in many earthquake-prone regions. These structures are often characterized by inadequate seismic detailing, limited ductility, and vulnerable beam-to-column connections, making them particularly susceptible to earthquake-induced damage. Reliable evaluation of their seismic performance requires advanced numerical methods capable of accurately reproducing nonlinear structural behavior while maintaining computational efficiency. This study presents a numerical framework for the seismic assessment of existing reinforced concrete prefabricated residential buildings based on the Fast Nonlinear Analysis (FNA) approach. A detailed three-dimensional finite element model was developed to represent the global dynamic behavior of a representative prefabricated residential building. The model incorporates the geometric configuration, mass distribution, stiffness characteristics, and connection details typical of construction practices predating modern seismic regulations. Structural nonlinearities were concentrated in predefined critical regions through plastic hinge formulations and nonlinear link elements, while the remaining structural members were modeled as linear elastic, providing an efficient yet accurate representation of the inelastic response. The seismic response was investigated using a suite of recorded earthquake ground motions. Engineering demand parameters, including interstory drifts, floor displacements, base shear, plastic hinge rotations, and residual deformations, were used to characterize the structural response and identify damage progression under increasing seismic demand. The numerical results were further compared with and calibrated against the performance requirements prescribed by current seismic design codes, enabling a consistent evaluation of the building's seismic capacity. The study demonstrates that the FNA approach accurately captures the global dynamic response and localized nonlinear mechanisms while substantially reducing computational effort compared with conventional nonlinear direct integration methods, providing an efficient framework for the seismic assessment of existing prefabricated reinforced concrete residential buildings.