A new type of seismic isolator with adjustable stiffness is proposed, based on the smart material of magnetorheological elastomers (MREs). This paper specifies the working principle of the isolator, analyses magnetic induction distribution of three different types of MRE isolators, which are unicoil magnetic energy input, twin coil magnetic energy input, and laminated steel plate coiling magnetic energy input respectively. The research shows that the third type of input produces relatively greater magnetic induction in the elastomer area, compared with the first two, and the magnetic field is evenly distributed in MRE area, therefore, it is the best structure. Eventually, the mechanical model of MRE isolator made of two steel slices and one elastomer slice is established together with the mechanical model made of multi-steel slices and multielastomer laminated structure. Furthermore, the numerical analysis is completed and the results show that MRE isolators have content adjustable behaviour.

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For this study, spruce–pine–fir (Picea–Pinus–Abies [SPF]) specification material, oriented strand board (OSB), and domestic twisted nails that were driven vertically and perpendicular-to-grain were selected. Referring to GB/T 13942.1-2009, nailed joints specimens were exposed both to white rot fungus and brown rot fungus for 1 month to 6 months. The monotonous loading test was applied to the specimens based on ASTM D1761-88. The holding power of the nails and weight loss of both OSB and SPF were investigated. Theoretical maximum load of the nailed joints was calculated according to Eurocode5. Results illustrated that the load, stiffness, and energy consumption of the nailed joints showed significant linear decline with the decay time. A linear decline of the ductility coefficient was not obvious, and there was no obvious difference between white rot fungus and brown rot fungus. Effect of decay on the OSB was much greater than the impact on the SPF. The decay grade of the nailed joints was established according to the linear relationship between weight loss and maximum load. Based on Eurocode5, the study calculated the maximum load of the nailed joints and introduced the correction coefficient γ to better predict the maximum load.