Dynamic test and numerical simulation on avoiding the weak-story failure mechanism in structures using LSFDs

The structural damage or collapse caused by weak-story failure mechanisms poses a great threat to the safety of human life and property under strong earthquakes. Many researchers have attempted to transform this unexpected failure mechanism into the desired overall failure mechanism by installing various energy dissipation devices on unsafe structures. This paper introduced a lattice-shaped friction device (LSFD), which is a friction device with hardening postyielding stiffness, into a steel frame with a weak-story failure mechanism. Then, shaking table tests of a three types of two-story steel frames—a frame with LSFDs, a frame with traditional friction brace dampers (FBDs), and a bare frame—were carried out. The seismic responses of the hardening postyielding stiffness of the LSFD on the weak-story failure mechanism of the frame were emphatically studied. The results showed that there was little difference in the seismic responses between the two damped structures under moderate and weak earthquakes. The distribution of maximum story drift for the structure with LSFDs was more uniform, which effectively suppressed the weak-story failure under strong earthquakes, whereas the structure with FBDs had serious deformation concentrations. The numerical simulation results of the structure with LSFDs in the shaking table test showed that the simplified model results were basically consistent with the experimental results. Hence, this model could be used to analyze the seismic performance of damped structures with LSFDs.