Large-Scale Experimental Testing and Numerical Modeling of Floor-to-Frame Connections for Controlled Rocking Steel Braced Frames

Controlled rocking steel braced frames (CRSBFs) are low-damage lateral force resisting systems that mitigate structural damage through a controlled rocking mechanism. Critical to the safety and low-damage nature of these systems are the floor-to-frame connections that allow the CRSBF to rock without imposing the associated uplifts on the adjacent gravity framing. This paper introduces three potential connection details through which the seismic forces are transferred to the CRSBF as the primary lateral force resisting system. The connections were tested at 60% scale between a one-story CRSBF subassembly and representative tributary gravity framing, with inertial and restoring forces simulated using hydraulic actuators for cyclic static testing. The experimental results show that all three connections are able to transfer the necessary loads while undergoing the displacements that are expected during a large earthquake, with some differences in the resistance that develops. These results are complimented by numerical simulations that are shown to be in good agreement. Design recommendations for the three proposed connections are also presented.