To improve the energy dissipation capacity of rubber isolation bearings, it is important to find a new rubber material with good applicability and high damping properties. Two types of blends were prepared using nitrile rubber (NBR), brominated butyl rubber (BIIR) and ethylene-vinyl acetate copolymer (EVA): NBR/BIIR and NBR/BIIR/EVA. The vulcanization, mechanical and damping properties of the blends were analyzed. The results show that both blends exhibit excellent vulcanization plateaus and mechanical properties. For NBR/BIIR, as the BIIR content increases, the complementary effects of NBR and BIIR afforded by blending are enhanced. Two damping peaks appeared in the tanδ-T curve and shifted toward lower and higher temperatures, respectively, which clearly widened the effective damping temperature range. However, the damping value in the valley of the tanδ-T curve was as low as 0.39. For NBR/BIIR/EVA, the addition of EVA greatly increased damping in the valley of the tanδ-T curve to approximately 0.54. EVA was observed to be the optimal polymer for improving the compatibility of the NBR/BIIR blend. Moreover, hot air thermal aging tests showed that both blends demonstrated good stability.

This paper presents an experimental study on the tensile behavior of basalt-fiber-grid-reinforced mortar (BGRM) before and after exposure to an elevated temperature of 300 °C considering the effect of fiber grid type, short polyvinyl alcohol fiber (PVA), and high-temperature exposure time. The experimental results show that the mortar plates reinforced with woven textile T25 and fiber-reinforced polymer (FRP) grid G50 exhibited more pronounced strain-hardening behavior. The highest peak stress was obtained for the T25-reinforced plate, which was 85% and 32% higher than that of the T5- and G50-reinforced plates, respectively. Meanwhile, the bridging effect of PVA fibers in mortar can improve the tensile properties. As the high-temperature exposure time increased, the cracking and peak stress of BGRM decreased significantly. Especially for the T5-reinforced plate after exposure to elevated temperature for 2 h, the cracking and peak stress decreased by 60.5% and 38%, respectively. The positive effect of short PVA fibers on the tensile properties of the BGRM became obsolete owing to the melting of short fibers at high temperature. Furthermore, an exponential strength degradation model related to high-temperature exposure time was proposed.

Due to the flammability of materials and the vastness of space, flashover fires of large-space timber structures pose a huge threat to lives as well as the structures themselves. Therefore, it is necessary to study the critical conditions, control factors and prediction methods of flashover fires. To address this issue, hundreds of design conditions were simulated by Fire Dynamics Simulator (FDS) with variations in space size, the heat release rate (HRR) of fire source and fire growth type. A temperature–time model of the maximum temperature of the smoke layer near the ceiling (T_max) was established, and the critical condition that uses this model to predict the occurrence of flashover was determined. Furthermore, a mathematical formula was established that can accurately predict the flashover induction time when the T_max exceeds 400 °C. This research can provide a reference for the performance-based fire safety design of large-space timber structures.