No abstract

In this study, a series of shaking table tests of a ten storey concrete suspended structure equipped with viscous dampers were carried out to evaluate the dynamic responses and vibration damping performance of suspended structures. The effects of link types between the primary structure and suspended floors and different seismic excitations on the response of suspended structure models was verified. The responses include the damping ratio, the frequency, maximum relative displacements, accelerations and maximum strains of the suspended structures. Test results showed that the damping ratio and the frequency of suspended structures installed with dampers (called damping suspended structure) are adjusted compared with a conventional suspended structure with rigid-bar links (conventional suspended structure). Maximum relative displacements of the primary structure of the damping suspended structure were distinctly smaller than those of the conventional suspended structure. However, the maximum relative displacement between the primary structure and the suspended floors of the damping suspended structure was significantly larger than that of the conventional structure, indicating that the swing of the suspended floor can help dissipate seismic energy. The peak acceleration and acceleration amplification factors of the damping suspended structure were less than the conventional suspended structure. Moreover, the peak acceleration response of the damping suspended structure was slightly behind the conventional suspended structure. The damping suspended structure certainly had a considerable and stable reduction for strain response, and the maximum strain response was decreased by 42.3%–72.7% for the damping suspended structure compared with the conventional suspended structure.

This paper is the world’s first to highlight an experimental investigation into the earthquake responses of a steel frame retrofitted by novel metallic bending energy absorbers made of low-yield-point steel with the yield strength of approximately 100 MPa. New results have been achieved by conducting comprehensive shaking table tests on a quarter-scaled model of a two-story, one-span building structure subjected to incremental intensity levels of input earthquake records. The detailed information of the specimens, material properties, monitoring sensors, and dynamic loading mechanisms has been presented. The experimental results in terms of seismic phenomena, dynamic characteristics, acceleration, inter-story drift ratios, and strain distributions are also analyzed by the data collected from a wide range of sensors. It is found that the seismic failure of the specimens depends largely on the energy absorbers, which dissipate the majority of seismic input energy in order to prevent the parent steel frame from being damaged by a severe earthquake. In addition, the retrofitted structure sufficiently satisfies the design criteria considering allowable drift limits under both frequent and rare earthquakes. This indicates the influential role of the novel low-yield-point absorber, in that the overall seismic performance of the retrofitted structure can be improved adequately for survival in high-intensity seismic fortification areas.

Wearable portable electronic devices have become an indispensable part of the modern lifestyle because of their smart, convenient, and fashionable features. Fiber-based nanogenerators are generally used as energy supply systems in wearable portable electronic devices. In the present work, poly(vinylidene fluoride) (PVDF) and poly(L-lactic acid) (PLLA) were used in triboelectric layers of hybrid tribopiezoelectric nanogenerators (HNGs). Twodimensional MXenes and one-dimensional multiwalled carbon nanotubes (MWCNTs-COOH) were used as conductive nanofillers introduced into electrospun nanofiber membranes. A 132fold increase in the electrical power density of a PVDF nanofiberbased piezoelectric nanogenerator was observed under the synergistic effect of MXenes and MWCNTs-COOH. Finiteelement simulations were performed to determine the optimum values of the triboelectric layer thickness and spacing for HNGs, and an MXenes/MWCNTs-COOH/PVDF-PPLA-based HNG with a power density of 18.08 W m −2 was constructed. We present a series of elaborations to demonstrate an effective way to improve the output performance of tribopiezoelectric nanogenerators. In addition, an HNGs-based wearable portable electronic device was fabricated to help humans interact with virtual reality.