As it has been learned from recent earthquakes, reinforced concrete buildings have historically been designed and constructed in ways that jeopardize their seismic performance. In particular, the early use of Precast Pre-stressed Hollow-Core (PPHC) floors saw the use of support connections that are susceptible to undesirable failure modes when subjected to earthquake-induced deformations. In the past twenty years, extensive experimental research programs in New Zealand have helped identify some of the main vulnerabilities of these floors and led to the development of support connection detailing capable of accommodating larger earthquake demands. While improved connection details have been developed, concerns regarding the seismic performance of buildings containing PPHC slabs have been raised following the 2016 Kaikōura Earthquake. The earthquake dynamic characteristics caused high drift demands on some multi-story moment frame buildings resulting in damage to floor diaphragms, in particular. Furthermore, post-earthquake observations evidenced inconsistencies between the observed damage conditions and the damage states identified by past research, bringing into question the seismic assessment of buildings with this type of floor system, the residual capacity of the floors once the damage has been sustained, and the effectiveness of existing retrofit techniques. This research presents a comprehensive three-dimensional finite element modeling approach for PPHC units, seating connections, and diaphragms, validated against experimental data collected from previous and ongoing research. This research permits investigation on the impact of a wider range of parameters than could practically be considered in laboratory testing and with more precise control of variables such as material properties, helping to inform methods for assessing, and improving the seismic performance of PPHC floors in New Zealand.