Beam Hoop Reinforcement for Large Beams in Special Moment Resisting Frames

Beam Hoop Reinforcement for Large Beams in Special Moment Resisting Frames

The tall building design community is in need of a testing program aimed at resolving the requirements for beam hoop reinforcement necessary to achieve adequate performance in large beams in special moment resisting frames (SMRF) in seismic environments. Reinforced concrete SMRFs are a common lateral force resisting system in regions of high seismicity. For tall reinforced concrete SMRF systems, beam cross sections with depth as large as 4 feet are not uncommon. Amount of confinement reinforcement for beam plastic hinges is still a matter of discussion, especially for higher concrete compressive strengths. No test data exist for large members to verify the adequacy of such hoop layout and spacing in satisfying the large plastic rotation demands for major earthquakes. It is important to establish the appropriate requirements. The results of this research study will be proposed for adoption as an ACI 318 code provision that will ensure improved seismic performance of certain reinforced concrete moment frame buildings.