Full-scale shake table tests of the tension-only concentrically braced steel beam-through frame

The tension-only concentrically braced steel beam-through frame (TCBBF) has the potential to enhance the seismic and post-earthquake performance for low-rise buildings in low to moderate seismic regions. To a better understanding of the dynamic response of TCBBFs, full-scale shake table tests under different seismic hazard levels and aftershocks were conducted on a three-story structural model. From the test results, the damage-control and low-residual-displacement behaviors were verified firstly. Under maximum considered earthquake (MCE), the main frame nearly remained elastic while all the braces yielded and there was almost no residual displacement. Under stronger earthquakes exceeding the MCE, yielding occurred at the beam-column connections, and the main frame demonstrated pinching behavior. Meanwhile, the residual displacement of the structure was still at a very low level. The tension-only braces played a key role in the seismic behavior. The existence of prestress made the braces able to sustain a little compression and thus increased the initial lateral stiffness of the structure. The slackness of the brace would enlarge story drift response and also induce dynamic impact due to the sudden tensioning. This impact effect was effectively controlled because of the high ductility of the braces. Tightening the slack braces was a convenient way to restore the structural behavior if the main frame was not damaged.