Existing hollow‐core floors are vulnerable to nonductile failure and potential collapse under earthquake loading. This study presents the development and experimental evaluation of novel comprehensive seismic retrofits for hollow‐core floors. These retrofits include a strongback‐type retrofit that provides an alternative gravity load path through steel beams positioned underneath the hollow‐core unit close to the support. In addition, a cable catch retrofit was developed to catch the floor in case it collapses. The retrofits were tested as part of a full‐scale super‐assembly experiment on a reinforced concrete moment frame structure with hollow‐core floors. Both retrofits prevented floor collapse throughout the experiment, which reached a peak inter‐story drift of 4.9%. The strongback retrofit effectively limited vertical deformation of the floor even when subjected to approximately twice the design gravity load. Despite the satisfactory performance of the cable catch retrofit, design and installation challenges are likely to make this retrofit option less desirable. The test also provided insights into the floor–retrofit interaction with broader implications beyond these specific retrofits. This research introduces new versatile retrofit options that can substantially enhance the hollow‐core floor performance and thereby improve life safety during earthquakes.
Büker et al. (Sun,) studied this question.