Shake-table test performance of an inertial force-limiting floor anchorage system

A new floor connecting system developed for low-damage seismic-resistant building structures is described herein. The system, termed Inertial Force-Limiting Floor Anchorage System (IFAS), is intended to limit the lateral forces in buildings during an earthquake. This objective is accomplished by providing limited-strength deformable connections between the floor system and the primary elements of the lateral force-resisting system. The connections transform the seismic demands from inertial forces into relative displacements between the floors and lateral force-resisting system. This paper presents the IFAS performance in a shake-table testing program that provides a direct comparison with an equivalent conventional rigidly anchored-floor structure. The test structure is a half-scale, 4-story reinforced concrete flat-plate shear wall structure. Precast hybrid rocking walls and special precast columns were used for test repeatability in a 22-input strong ground-motion sequence. The structure was purposely designed with an eccentric wall layout to examine the performance of the system in coupled translational-torsional response. The test results indicated a seismic demand reduction in the lateral force-resisting system of the IFAS structure relative to the conventional structure, including reduced shear wall base rotation, shear wall and column inter-story drift, and, in some cases, floor accelerations. These results indicate the potential for the IFAS to minimize damage to the primary structural and non-structural components during earthquakes.